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Chemical Properties of Fluoropolymers
PART III 12 Chemical Properties of Fluoropolymers 12.1 Introduction A fundamental property of fluoropolymers is their resistance to organic and inorganic chemicals (Fig. 12.1). Increased content of fluorine enhances the chemical resistance of the polymer. The overwhelming majority of the applications of fluoropolymers take advantage of their inertness to chemicals. Chemical properties of fluoropolymers are not affected by fabrication conditions. Another aspect of the interaction of these plastics with chemicals is permeation. Even though a reagent may not react with a fluoropolymer, it may be able to permeate through the polymer structure. The extent and rate of permeation is dependent upon the structure and properties of the plastic article as well as the type and concentration of permeant. Temperature and pressure usually influence the permeation process. This chapter reviews chemical compatibility of fluoropolymers and their permeation behavior towards different chemicals. This chapter has been divided based on the fluorine content of fluoropolymers, that is, perfluorinated or partially fluorinated. In general, resistance of polymers to chemicals of all types increases with an increase in their fluorine content. Therefore, the chemi-
Figure 12.1 Chemical resistance of fluoropolymers.[1]
© Plastics Design Library
cal resistance of ETFE, ECTFE, and PVDF is generally inferior to that of perfluorinated polymers such as PFA and FEP.
12.2 Chemical Compatibility of Perfluoropolymers Perfluoropolymers such as PTFE, PFA, and FEP are by far the most chemically resistant among thermoplastics. Few substances chemically interact with these plastics. The exceptions among the commercially encountered materials include alkali metals, especially in a molten state, and gaseous fluorine at high temperatures and pressures. Perfluoropolymers are attacked by certain halogenated compounds containing fluorine such as chlorine trifluoride (ClF3), bromine trifluoride, iodine pentafluoride, and oxygen difluoride (OF2). The inertness of these polymers arises from their molecular structure.[2] A few chemicals have been reported to attack perfluoropolymers at or near their upper service temperature (260°C).[3] They react with 80% sodium or potassium hydroxide. They also react with some strong Lewis bases including metal hydrides such as boranes (B2H6), aluminum chloride, ammonia, and some amines (RNH2) and imines (R=NH). Slow oxidative attacks may take place in the presence of 70% nitric acid at 250ºC under pressure. It is important to test the effect of these reagents on perfluoropolymers under the specific application temperature to determine the material limitations. Perfluoropolymers derive their chemical resistance from an extremely strong carbon-fluorine bond and an impermeable sheath of fluorine atoms surrounding the carbon-carbon chain. Relatively high crystalline content renders these polymers insoluble in solvents. Tables 12.1 and 12.2 summarize the effect of a number of representative organic and inorganic compounds on tetrafluoroethylene-perfluoropropyl vinyl ether polymer (PFA). Figure 12.2 gives a comparison of PFA and MFA (copolymer of tetrafluoroethylene and perfluoromethyl vinyl ether). Tables 12.312.6 summarize the effect of a number of representative organic and inorganic compounds on FEP.
Ch. 12: Chemical Properties of Fluoropolymers
338 Table 12.1. Effect of Immersion in Inorganic Chemicals for 168 hours on PFA.[4]
Exposure Temperature, ºC
Tensile Strength Retained, %
Elongation Retained, %
Weight Gain, %
Hydrochloric (conc.)
120
98
100
0
Sulfuric (conc.)
120
95
98
0
Hydrofluoric (60%)
23
99
99
0
Fuming Sulfuric
23
95
96
0
Aqua Regia
120
99
100
0
Chromic (50%)
120
93
97
0
Nitric (conc.)
120
95
98
0
Fuming Nitric
23
99
99
0
Ammonium Hydroxide (conc.)
66
98
100
0
Sodium Hydroxide (conc.)
120
93
99
0.4
23
93
95
0
Bromine
23
99
100
0.5
Bromine
59
95
95
-
Chlorine
120
92
100
0.5
Ferric Chloride
100
93
98
0
Zinc Chloride (25%)
100
96
100
0
Sulfuryl Chloride
69
83
100
2.7
Chlorosulfonic Acid
151
91
100
0.7
Phosphoric Acid (conc.)
100
93
100
0
Reagent Acids:
Oxidizing Acids:
Bases:
Peroxide: Hydrogen Peroxide (30%) Halogens:
Metal Salt Solutions:
Miscellaneous:
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
339 Table 12.2. Effect of Immersion in Organic Chemicals for 168 hours on PFA[4] Exposure Temperature, ºC
Tensile Strength Retained, %
Elongation Retained, %
Weight Gain, %
Glacial Acetic Acid
118
95
100
0.4
Acetic Anhydride
139
91
99
0.3
Trichloroacetic Acid
196
90
100
2.2
Isooctane
99
94
100
0.7
Naphtha
100
91
100
0.5
Mineral Oil
180
87
95
0
Toluene
110
88
100
0.7
O-Cresol
191
92
96
0.2
Nitrobenzene
210
90
100
0.7
205
93
99
0.3
66
88
100
0.7
Aniline
185
94
100
0.3
n-Butylamine
78
86
97
0.4
Ethylenediamine
117
96
100
0.1
179
90
99
0.5
Cyclohexanone
156
92
100
0.4
Methyl Ethyl Ketone
80
90
100
0.4
Acetophenone
202
90
100
0.6
Dimethylphthalate
220
98
100
0.3
n-Butylacetate
125
93
100
0.5
Tri-n-Butyl Phosphate
200
91
100
2.0
40
94
100
0.8
121
86
100
2.0
77
87
100
2.3
Dimethylformamide
154
96
100
0.2
Dimethylsulfoxide
189
95
100
0.1
Dioxane
101
92
100
0.6
Reagent Acids/Anhydrides:
Hydrocarbons:
Aromatic:
Alcohol: Benzyl Alcohol Ether: Tetrahydrofuran Amine:
Aldehyde: Benzaldehyde Ketone:
Esters:
Chlorinated Solvents: Methylene Chloride Perchloroethylene Carbon Tetrachloride Polar Solvents:
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
340
A:
Cylcohexanone @ 156ºC
B:
Toluene @ 110ºC
C:
Carbon tetrachloride @ 77ºC
D:
Dimethylformamide @ 40ºC
E:
Methylene chloride @ 40ºC
F:
Fuming nitric acid @ 23ºC
G: Fuming sulfuric acid @ 23ºC H:
Phosphoric acid 85% @ 100ºC
I:
MEK @ 80ºC
J:
Hydrogen peroxide 30% @ 23ºC
K:
Zinc chloride 25% @ 100ºC
L:
Ethylene diamine @ 117ºC
M: Sodium hydroxide @ 120ºC
Figure 12.2 A comparison of chemical resistance of PFA and MFA.[5]
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
341 Table 12.3. Chemical Resistance of FEP to Common Solvents[6]
Solvent
Acetone
Benzene
Carbon Terachloride
Ethanol (95%)
Ethyl Acetate
Toluene
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Exposure Temperature, ºC
Exposure Time
Weight Gain, %
20
12 mo
0.3
50
12 mo
0.4
70
2 wk
0
78
96 hr
0.5
100
8 hr
0.6
200
8 hr
1.0
25
12 mo
0.6
50
12 mo
1.6
70
2 wk
1.9
100
8 hr
2.5
200
8 hr
3.7
25
12 mo
0
50
12 mo
0
70
2 wk
0
100
8 hr
0.1
200
8 hr
0.3
25
12 mo
0.5
50
12 mo
0.7
70
2 wk
0.7
25
12 mo
0.3
50
12 mo
0.6
70
2 wk
0.6
Ch. 12: Chemical Properties of Fluoropolymers
342 Table 12.4. Chemical Resistance of FEP to Common Acids and Bases[6] Reagent Hydrochloric Acid 10% 10% 10% 20% 20% Nitric Acid 10% 10% Sulfuric Acid 30% 30% 30% 30% Sodium Hydroxide 10% 10% 50% 50% Ammonium Hydroxide 10% 10%
Exposure Temperature, ºC
Exposure Time
Weight Gain, %
25 50 70 100 200
12 mo 12 mo 12 mo 8 hr 8 hr
0 0 0 0 0
25 70
12 mo 12 mo
0 0.1
25 70 100 200
12 mo 12 mo 8 hr 8 hr
0 0 0 0.1
25 70 100 200
12 mo 12 mo 8 hr 8 hr
0 0.1 0 0
25 70
12 mo 12 mo
0 0.1
Table 12.5. Chemical Compatibility of FEP with Halogenated Chemicals[6] Chemical
Effect on Polymer Sample
Chloroform
Wets, insoluble at boiling point
Ethylene Bromide
0.3% weight gain after 24 hr at 100°C
Fluorinated Hydrocarbons
Wets, swelling occurs in boiling solvent
Fluoro-naphthalene
Insoluble at boiling point, some swelling
Fluoronitrobenzene
Insoluble at boiling point, some swelling
Pentachlorobenzamide
Insoluble
Perfluoroxylene
Insoluble at boiling point, slight swelling
Tetrabromoethane
Insoluble at boiling point
Tetrachloroethylene
Wets, some swelling after 2 hr at 120°C
Trichloroacetic Acid
Insoluble at boiling point
Trichloroethylene
Insoluble at boiling point after 1 hr
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
343 Table 12.6. Chemical Compatibility of FEP with Various Chemicals[6]
Chemical
Effect on Polymer Sample
Abietic Acid
Insoluble at boiling point
Acetic Acid
Wets
Acetophenone
Insoluble 0.2% weight gain after 24 hr at 150°C
Acrylic Anhydride
No effect at room temperature
Allyl Acetate
No effect at room temperature
Allyl Methacrylate
No effect at room temperature
Aluminum Chloride
Insoluble in solution with NaCl; 15% anhydrous AlCl3 affects mechanical properties
Ammonium Chloride
Insoluble at boiling point
Aniline
Insoluble 0.3% weight gain after 24 hr at 150°C
Borax
No wetting or effect by 5% solution
Boric Acid
Insoluble at boiling point
Butyl Acetate
Insoluble at boiling point
Butyl Methacrylate
No effect at room temperature
Calcium Chloride
No effect by saturated solution in methanol
Carbon Disulfide
Insoluble at boiling point
Cetane
Wets, insoluble at boiling point
Chromic Acid
Insoluble at boiling point
Cyclohexanone
No effect observed
Dibutyl Phthalate
Wets, no effect at 250°C
Diethyl Carbonate
No effect at the room temperature
Dimethyl Ether
No effect observed
Dimethyl Formamide
No effect observed
Ethyl Ether
Wets
Ethylene Glycol
Insoluble at boiling point
Ferric Chloride
15% FeCl3·6H2O reduces mechanical properties
Ferric Phosphate
No effect by 5% solution
Formaldehyde
Insoluble at boiling point after 2 hr
Formic Acid
Insoluble at boiling point
Hexane
Wets
Hydrogen Fluoride
Wets, no effect by 100% HF at the room temperature
Lead
No effect
Magnesium Chloride
Insoluble at boiling point
Mercury
Insoluble at boiling point
Methacrylic Acid
No effect at the room temperature
Methanol
Wets
Methyl Methacrylate
Wets above melting point
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
344 Table 12.6. (Contd.) Chemical
Effect on Polymer Sample
Naphthalene
No effect
Nitrobenzene
No effect
2-Nitro-Butanol
No effect
Nitromethane
No effect
2-Nitro-2-Methyl Propanol
No effect
n-Octadecyl Alcohol
Wets
Phenol
Insoluble at boiling point
Phthalic Acid
Wets
Pinene
Wets, insoluble at boiling point
Piperidene
No effect, 0.30.5% weight gain after 24 hr at 106°C
Polyacrylonitrile
No effect
Potassium Acetate
Insoluble at boiling point
Pyridine
No effect
Stannous Chloride
No effect at melting point (246°C)
Sulfur
No effect at 445°C
Triethanolamine
Wets, no effect
Vinyl Methacrylate
No effect at the room temperature
Water
Insoluble at boiling point
Xylene
0.4% weight gain after 48 hr at 137°C
Zinc Chloride
No effect at melting point (260°C)
Another commercially significant perfluoropolymer is the copolymer of tetrafluoroethyleneperfluoromethylvinylether. It has chemical resistance characteristics similar to the other perfluoropolymers. Some halogenated solvents are absorbed by perfluoropolymers without any chemical interaction or degradation. The action is strictly physical and the removal of the absorbed species restores it to its original state. Too much absorption by a perfluoropolymer sample can be an indication of excessive porosity. A highly porous sample may appear blistered due to the expansion of vapors in the surface pores. A properly fabricated part does not exhibit blistering. Appendix I contains data about the effect of high temperature automotive fuels on the physical properties of fluoropolymers.
Ch. 12: Chemical Properties of Fluoropolymers
12.3 Chemical Compatibility of Partially Fluorinated Fluoropolymers Partially fluorinated fluoropolymers with commercial significance include ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF). The presence of hydrogen in these plastics lowers the fluorine content compared to perfluoropolymers, and renders them susceptible to some chemicals. This means that care must be taken in the selection of these polymers to insure compatibility of process fluids. ETFE has excellent resistance to a great many chemicals. It is somewhat affected by oxidizers, chlorinated solvents, ketones, and esters but resists acids, alkalis, and organic solvents. Table 12.7 lists chemicals and the suggested maximum use temperature.
© Plastics Design Library
345 Table 12.7. Chemical Compatibility of ETFE[7] Chemical A Acetaldehyde
Maximum Use Temperature, °C 95
Chemical
Maximum Use Temperature, °C
Ammonium Sulfide
150
Ammonium Thiocyanate
150
Acetamide
120
Amyl Acetate
120
Acetic Acid (50%)
110
Amyl Alcohol
150
Acetic Acid (Glacial)
120
Amyl Chloride
150
Acetic Anhydride
150
Aniline
110
Acetone
65
Aniline Hydrochloride (10%)
65
Acetone(50% H2O)
65
Anthraquinone
135
Acetonitrile
65
Anthraquinone-Sulfonic Acid
135
Antimony Trichloride
100
Acetophenone Acetylchloride
150 65
Aqua Regia
100
Acetylene
120
Arsenic Acid
150
Acetylene Tetrabromide
150
B
Acetylene Tetrachloride
150
Barium Carbonate
150
Barium Chloride
150
Acrylonitrile
65
Adipic Acid
135
Barium Hydroxide
150
Air
150
Barium Sulfate
150
Allyl Alcohol Allyl Chloride
100 100
Barium Sulfide Battery Acid
150 120
Aluminum Ammonium Sulfate
150
Benzaldehyde
100
Aluminum Chloride
150
Benzene
100
Aluminum Fluoride
150
Benzene Sulfonic Acid
100
Aluminum Hydroxide
150
Benzoic Acid
135
Aluminum Nitrate
150
Benzoyl Chloride
65
Aluminum Oxychloride
150
Benzyl Alcohol
150
Aluminum Potassium Sulfate
150
Benzyl Chloride
150
Amino Acids (H2O)
100
Bismuth Carbonate
150
Ammonia (Anhydrous)
150
Black Liquor
150
Ammonia (Aqueous 30%)
110
Bleach (12.5% Cl2)
100
Ammonium Bifluoride
150
Borax
150
Ammonium Bromide (50%)
135
Boric Acid
150
Ammonium Carbonate
150
Brine
150
Ammonium Chloride
150
Bromic Acid
120
Ammonium Dichromate
135
Bromine (Dry)
65
Ammonium Fluoride
150
Bromine Water (10%)
110
Ammonium Hydroxide
150
mono-Bromobenzene
100
Ammonium Nitrate (Conc.)
110
Bromoform
100
Ammonium Perchlorate
135
m-Bromotoluene
100
Ammonium Persulfate
150
Butadiene
120
Ammonium Phosphate
150
Butane
150
Ammonium Sulfate
150
Butanediol
135
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
346 Table 12.7. (Contd.) Chemical Butyl Acetate
Maximum Use Temperature, °C 110
Butyl Acrylate
110
n-Butyl Alcohol
150
sec-Butyl Alcohol
150
tert-Butyl Alcohol
150
n-Butylamine
50
sec-Butylamine
50
tert-Butylamine
50
di-n-Butyl Amine
110
tri-n-Butyl Amine
110
Butylene
150
Butyl Bromide
150
Butyl Chloride
150
Chemical
Maximum Use Temperature, °C
Chloral Hydrate
100
Chlorinated Brine
120
Chlorinated Phenol
100
Chlorine (Dry)
100
Chlorine (Wet)
120
Chlorine Dioxide
120
Chloroacetic Acid (50% H2O)
110
Chlorobenzene
100
Chlorobenzyl Chloride
65
Chloroform
100
Chlorohydrin (Liquid)
65
Chlorosulphonic Acid
25
Chromic Acid (50%)
65
Chromic Chloride
100
Chromyl Chloride
100
n-Butyl Mercaptan
150
Butyl Phenol
110
Butyl Phthalate
65
Butyraldehyde
100
Clorox Bleach Solution (5-1/2% Cl2)
100
Butyric Acid
120
Coal Gas
100
Copper Chloride
150
C Calcium Bisulfate
150
Copper Cyanide
150
Calcium Bisulfide
150
Copper Fluoride
150
Calcium Carbonate
150
Copper Nitrate
150
Calcium Chlorate
150
Copper Sulfate
150
Calcium Chloride
150
Cresol
135
Calcium Hydroxide
150
Cresylic Acid
135
Calcium Hypochlorite
150
Crotonaldehyde
100
Calcium Nitrate
150
Crude Oil
150
Calcium Oxide
135
Cyclohexane
150
Calcium Sulfate
150
Cyclohexanol
120
Calcium Sulfide
120
Cyclohexanone
150
Caprylic Acid
100
D
Carbon Dioxide (Dry)
150
DDT
Carbon Dioxide (Wet)
150
Decalin
120
Carbon Disulfide
65
Decane
150
Carbon Monoxide
150
Dextrin
150
Carbon Tetrachloride
135
Diacetone Alcohol
100
Carbonic Acid
150
1,2-Dibromopropane
95
Castor Oil
150
Dibutyl Phthalate
65
Caustic Potash (10 and 50%)
100
Dichloroacetic Acid
65
Caustic Soda (10 and 50%)
100
o-Dichlorobenzene
65
150
Dichloroethylene
65
Cellosolve
®
Ch. 12: Chemical Properties of Fluoropolymers
100
© Plastics Design Library
347 Table 12.7. (Contd.) Chemical Dichloropropionic Acid
Maximum Use Temperature, °C 65
Chemical
Maximum Use Temperature, °C
Ferric Hydroxide
150
150
Ferric Nitrate
150
Diethyl Benzene
135
Ferric Sulfate
150
Diethyl Cellosolve
150
Ferrous Chloride
150
Diethyl Ether
100
Ferrous Hydroxide
150
Diethylamine
110
Ferrous Nitrate
150
Diethylene Triamine
100
Ferrous Sulfate
150
Diglycolic Acid
100
Fluorine (Gaseous)
40
Diisobutyl Ketone
100
Fluoroboric Acid
135
Diisobutylene
135
Fluosilicic Acid
135
Dimethyl Formamide
120
Formaldehyde (37% in H2O)
110
Dimethyl Phthalate
100
Formic Acid
135
Dimethyl Sulfate
65
FREON 11
110
FREON 12
110
Diesel Fuels
Dimethyl Sulfoxide
100
® ® ®
Dimethylamine
50
FREON 22
110
Dimethylaniline
135
Fuel Oil
150
Dioctyl Phthalate
65
Fumaric Acid
95
p-Dioxane Diphenyl Oxide
65 80
Furane Furfural
65 100
Divinyl Benzene
80
G
E Epichlorhydrin
Gallic Acid
100
65
GasManufactured
150
Ether
100
GasNatural
150
Ethyl Acetate
65
GasolineLeaded
150
Ethyl Alcohol
150
GasolineSour
150
Ethylamine
40
GasolineUnleaded
150
Esters
65
Glycerol
150
Ethylacetoacetate
65
Glycol
135
Ethyl Acrylate
100
Glycolic Acid
120
Ethyl Chloride
150
H
Ethyl Chloroacetate
100
Heptane
150
Ethyl Cyanoacetate
100
Hexane
150
Ethylene Bromide
150
Hydrazine
40
Ethylene Chloride
150
Hydrazine Dihydrochloride
50
Ethylene Chlorohydrin
65
Hydriodic Acid
150
Ethylene Diamine
50
Hydrobromic Acid (50%)
150
Ethylene Glycol
150
Hydrochloric Acid (20%)
150
Ethylene Oxide
110
Hydrochloric Acid (Conc.)
150
F Fatty Acids
Hydrochloric Acid (Gas)
150
150
Hydrocyanic Acid
150
Ferric Chloride (50% in H2O)
150
Hydrofluoric Acid (35%)
135
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
348 Table 12.7. (Contd.) Chemical
Maximum Use Temperature, °C
Chemical
Maximum Use Temperature, °C 95
Hydrofluoric Acid (70%)
120
Maleic Anhydride
Hydrofluoric Acid (100%)
110
Malic Acid
135
Hydrofluorosilicic Acid
150
Mercuric Chloride
135
Hydrogen
150
Mercuric Cyanide
135
Hydrogen Cyanide
150
Mercuric Nitrate
135
Hydrogen Peroxide (30%)
120
Mercury
135
Hydrogen Peroxide (90%)
65
Methacrylic Acid
95
Hydrogen Phosphide
65
Methane
120
Hydrogen Sulfide (Dry)
150
Methane Sulfonic Acid (50%)
110
Hydrogen Sulfide (Wet)
150
Methyl Alcohol
150
Hydroquinone
120
n-Methylaniline
120
150
Methyl Benzoate
120
Hypochlorous Acid
Methyl Bromide
I
150 ®
Inert Gases
150
Methyl Cellosolve
Iodine (Dry)
110
Methyl Chloride
150
Iodine (Wet)
110
Methyl Chloroform
65
Iodoform
110
Methyl Chloromethyl Ether
80
Isobutyl Alcohol Isopropylamine
135 50
Methyl Cyanoacetate Methyl Ethyl Ketone
80 110
Methyl Isobutyl Ketone
110
J
150
Jet FuelJP4
110
Methyl Methacrylate
80
Jet FuelJP5
110
Methyl Salicylate
95
L
Methyl Sulfuric Acid
100
Lactic Acid
120
Methyl Trichlorosilane
95
Lard Oil
150
Methylene Bromide
100
Lauric Acid
120
Methylene Chloride
100
Lauryl Chloride
135
Methylene Iodide
100
Lauryl Sulfate
120
Mineral Oil
150
Lead Acetate
150
Monochlorobenzene
110
Linoleic Acid
135
Monoethanolamine
65
Linseed Oil
150
Morpholine
65
Lithium Bromide (Saturated)
120
Lithium Hydroxide
150
N Naphtha
150
Lubricating Oil
150
Naphthalene
150
M
Nickel Chloride
150
Magnesium Carbonate
150
Nickel Nitrate
150
Magnesium Chloride
150
Nickel Sulfate
150
Magnesium Hydroxide
150
Nicotine
100
Magnesium Nitrate
150
Nicotinic Acid
120
Magnesium Sulfate
150
Nitric Acid (50%)
65
Maleic Acid
135
Nitric Acid (Conc. 70%)
25
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
349 Table 12.7. (Contd.) Chemical
Maximum Use Temperature, °C
Chemical
Maximum Use Temperature, °C 150
Nitric AcidSulfuric Acid (50/50)
100
Potassium Aluminum Chloride
Nitrobenzene
150
Potassium Aluminum Sulfate (50%)
150
Nitrogen Dioxide
100
Potassium Bicarbonate
150
Nitrogen Gas
150
Potassium Borate
150
Nitromethane
100
Potassium Bromate
150
Nitrous Acid
100
Potassium Bromide
150
Potassium Carbonate
150
O Octane
150
Potassium Chlorate
150
Octene
150
Potassium Chloride
150
Oleic Acid
135
Potassium Chromate
150
Oleum
50
Potassium Cyanide
150
Oxalic Acid
110
Potassium Dichromate
150
Oxygen
150
Potassium Ferrocyanide
150
Ozone (<1% in Air)
100
Potassium Fluoride
150
Potassium Hydroxide (50%)
100
P Palmitic Acid
135
Potassium Hypochlorite
135
Perchlorethylene
135
Potassium Nitrate
150
Perchloric Acid (10%)
110
Potassium Perborate
135
Perchloric Acid (72%)
65
Potassium Perchlorate
100
Petrolatum
150
Potassium Permanganate
150
Petroleum
150
Potassium Persulfate
65
Petroleum Ether
100
Potassium Sulfate
150
Phenol (10%)
110
Potassium Sulfide
150
Phenol (100%)
100
Propane
135
Phenolsulfonic Acid
100
Propionic Acid
100
Phenylhydrazine
100
Propyl Alcohol
100
Phenylhydrazine Hydrochloride
100
Propylene Dibromide
100
o-Phenylphenol
100
Propylene Dichloride
100
Phosgene
100
Propylene Glycol Methyl Ether
100
Phosphoric Acid (30%)
150
Propylene Oxide
65
Phosphoric Acid (85%)
135
Pyridine
65
Phosphorus Pentoxide
110
Pyrogallol
65
Phosphorus Oxychloride
100
Phosphorus Pentachloride
100
S Salicylaldehyde
100
Phosphorus Trichloride
120
Salicylic Acid
120
Phthalic Acid
100
Salt Brine
150
Phthalic Anhydride
100
Sea Water
150
Picric Acid
50
Silicon Tetrachloride
120
Polyvinyl Acetate
150
Silver Chloride
150
Polyvinyl Alcohol
150
Silver Cyanide
150
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
350 Table 12.7. (Contd.) Chemical Silver Nitrate
Maximum Use Temperature, °C 150
Maximum Use Temperature, °C 150
Chemical Stannic Chloride
Sodium Acetate
150
Stannous Chloride
150
Sodium Benzene-Sulfonate
150
Stannous Fluoride
120
Sodium Benzoate
150
Stearic Acid
150
Sodium Bicarbonate
150
Stoddards Solvent
135
Sodium Bisulfate
150
Styrene Monomer
100
Sodium Bisulfite
150
Succinic Acid
135
Sodium Borate
100
Sulfamic Acid
100
Sodium Bromide
150
Sulfur (Molten)
120
Sodium Carbonate
150
Sulfur Dioxide
110
Sodium Chlorate
150
Sulfur Trioxide (Liquid)
25
Sodium Chloride
150
Sulfuric Acid (60%)
150
Sodium Chromate
150
Sulfuric Acid (Conc.)
150
Sodium Cyanide
150
Sulfuric Acid (FumingOleum)
50
Sodium Dichromate (Alkaline)
100
Sulfurous Acid
110
Sodium Ferricyanide
150
150
Sodium Ferrocyanide
150
T Tall Oil
Sodium Fluoride Sodium Glutamate
150 135
Tannic Acid Tartaric Acid
135 135
Sodium Hydroxide (10%)
110
2,3,4,6-Tetrachlorophenol
100
Sodium Hydroxide (50%)
110
Tetraethyl Lead
150
Sodium Hypochlorite
150
Tetrahydrofuran
100
Sodium Hyposulfite
150
Sodium Iodide
150
Tetramethyl Ammonium Hydroxide (50%)
100
Sodium Lignosulfonate
150
Sodium Metasilicate
150
Sodium Nitrate
150
Sodium Nitrite
150
Sodium Perborate
100
Sodium Perchlorate
65
Sodium Peroxide
150
Sodium Persulfate
80
Sodium Phosphate
150
Sodium Silicate
150
Sodium Silicofluoride
150
Sodium Sulfate
150
Sodium Sulfide
150
Sodium Sulfite
150
Sodium Thiosulfate
150
Sorbic Acid
135
Sour Crude Oil
150
Ch. 12: Chemical Properties of Fluoropolymers
Tin Tetrachloride
110
Toluene
120
Tributyl Phosphate
65
Trichloracetic Acid
100
Trichloroethylene
135
Trichloromethane
100
2,4,5-Trichlorophenol
100
Triethylamine
110
Trisodium Phosphate
135
Thionyl Chloride
100
Titanium Dioxide
150
Titanium Tetrachloride
100
Turpentine
135
U UDMH-Hydrazine (50/50)
50
Urea (50% H2O)
135
© Plastics Design Library
351 Table 12.7. (Contd.) Chemical
Maximum Use Temperature, °C
V Varsol
135
Vinyl Acetate
135
Vinyl Chloride (Monomer)
65
W Water
150
Water Sewage
135
Wax
150
X Xylene
120
Z Zinc Acetate
120
Zinc Chloride
150
Zinc Hydrosulfite (10%)
120
Zinc Nitrate
150
Zinc Sulfate
150
Zinc Sulfide
150
PLATING SOLUTIONS Brass
135
Cadmium
135
Chrome
135
Copper
135
Gold
135
Tests should be conducted in each specific application to verify the validity of the values provided. More specific data, based on aging experiments, have been listed in Table 12.8, which indicate the retained tensile properties and ETFE weight gain. Hydrolytic stability of ETFE is indicated by retention of its physical properties after extensive exposure to boiling water. Tensile strength and elongation changed little after 3,000 hours exposure of unfilled ETFE to boiling water (Table 12.9). PVDF, in general, resists inorganic acids, bases, salt solutions, oxidizing agents, and halogens. It is, however, attacked by concentrated sulfuric acid and medium concentration alkaline solutions. PVDF is
© Plastics Design Library
unaffected by alcohols, chlorinated solvents, aliphatic and aromatic hydrocarbons, and crude oil. It swells in some polar solvents such as ketones and esters. PVDF dissolves in some polar solvents like dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. Hot amines attack polyvinylidene fluoride. Table 12.10 indicates the maximum use temperature of PVDF for many chemicals. ECTFE is resistant to strong mineral and oxidizing acids, alkalis, metal etchants, liquid oxygen, and virtually all organic solvents with the exception of hot amines such as aniline and dimethyl amine. ECTFE is susceptible to attack by metallic sodium and potassium; the rate of attack is dependent on the time and temperature of exposure. Certain halogenated solvents can plasticize ECTFE without impairing its usefulness. After discontinuing contact between the part and the solvent, it dries and mechanical properties return to the original values. A conclusion of this observation is that the interaction between ECTFE and the solvents in these cases is strictly physical and not chemical. Table 12.11 gives the impact of a number of chemicals on ECTFE including tensile properties, weight gain, and color change. ECTFE is compatible with liquid oxygen (LOX) as measured by National Aeronautics and Space Administration (NASA) test method MSFCSPEC-106B. It is also resistant to nitrogen tetroxide (NTO) and monomethylhydrazine (MMH). Polyvinyl fluoride is resistant to most organic and inorganic chemicals. It is susceptible to strong oxidizing agents and alkaline metals such as sodium. In general, any chemical that affects fluoropolymers with higher fluorine content, such as PTFE, PFA, and ETFE, also attacks PVF. Table 12.12 provides swelling data for PVF immersed in a number of polar solvents.
12.4 Permeation Fundamentals Permeation can be defined as the passage of gases and liquids through a second material such as a solid. It is a significant consideration in the selection of plastic material for the construction of chemical processing equipment because process fluids may travel across the thickness of the polymer by permeation. Permeated species in sufficient quantities could cause corrosion, contamination, or unacceptable environmental emission, singly or in combination.
Ch. 12: Chemical Properties of Fluoropolymers
352 Table 12.8. Effect of Immersion in Various Chemicals on ETFE[7]
Retained Properties%
Boiling Point, °C
Test Temp., °C
Days
Tensile Strength
Elong.
Weight Gain
Acetic Acid (Glacial)
118
118
7
82
80
3.4
Acetic Anhydride
139
139
7
100
100
0
Trichloroacetic Acid
196
100
7
90
70
0
Trichloroacetic Acid
196
120
30
100
100
Mineral Oil
180
7
90
60
0
Naphtha
100
7
100
100
0.5
Benzene
80
80
7
100
100
0
Toluene
110
110
7
191
180
7
100
100
0
Aniline
185
120
7
81
99
2.7
Aniline
185
120
30
93
82
Aniline
185
180
7
95
90
N,N-Dimethylaniline
190
120
7
82
97
N-Methylaniline
195
120
7
85
95
N-Methylaniline
195
120
30
100
100
n-Butylamine
78
78
7
71
73
4.4
Di-n-Butylamine
159
120
7
81
96
Di-n-Butylamine
159
120
30
100
100
Di-n-Butylamine
159
160
7
55
75
Tri-n-Butylamine
216
120
7
81
80
Tri-n-Butylamine
216
120
30
100
100
Pyridine
116
116
7
100
100
1.5
Carbon Tetrachloride
78
78
7
90
80
4.5
Chloroform
62
61
7
85
100
4.0
Dichloroethylene
77
32
7
95
100
2.8
®
FREON 113
46
46
7
100
100
0.8
Methylene Chloride
40
40
7
85
85
0
Chemical Acid/Anhydrides
Aliphatic Hydrocarbons
Aromatic Hydrocarbons
Functional Aromatics O-Cresol Amines
Chlorinated Solvents
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
353 Table 12.8. (Contd.)
Retained Properties%
Boiling Point, °C
Test Temp., °C
Days
Tensile Strength
Elong.
Weight Gain
66
66
7
86
93
3.5
Acetone
56
56
7
80
83
4.1
Acetophenone
201
180
7
80
80
1.5
Cyclohexanone
156
156
7
90
85
0
Methyl Ethyl Ketone
80
80
7
100
100
0
n-Butyl Acetate
127
127
7
80
60
0
Ethyl Acetate
77
77
7
85
60
0
Dimethylformamide
154
90
7
100
100
1.5
Dimethylformamide
154
120
7
76
92
5.5
Dimethylsulfoxide
189
90
7
95
90
1.5
Benzoyl Chloride
197
120
7
94
95
Benzoyl Chloride
197
120
30
100
100
Benzyl Alcohol
205
120
7
97
90
Decalin
190
120
7
89
95
Phthaloyl
276
120
30
100
100
0
Aqua Regia
90
*
93
89
0.2
Chromic
125
125
7
66
25
Hydrobromic (Conc)
125
125
7
100
100
Hydrochloric (Conc)
106
23
7
100
90
0
Hydrochloric (Conc)
106
106
7
96
100
0.1
Hydrofluoric (Conc)
23
7
97
95
0.1
Nitric25%
100
100
14
100
100
Nitric50%
105
105
14
87
81
Nitric70% (Conc)
120
23
105
100
100
0.5
Nitric70% (Conc)
120
60
53
100
100
Nitric70% (Conc)
120
120
2
72
91
Nitric70% (Conc)
120
120
3
58
5
Nitric70% (Conc)
120
120
7
0
0
Chemical Ethers Tetrahydrofuran Aldehyde/Ketones
Esters
Polymer
Other Organics
Acids
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
354 Table 12.8. (Contd.)
Retained Properties%
Boiling Point, °C
Test Temp., °C
Days
Tensile Strength
Elong.
Weight Gain
Phosphoric (Conc)
100
7
Phosphoric (Conc)
120
7
94
93
0
Sulfuric (Conc)
100
7
100
100
0
Sulfuric (Conc)
120
7
98
95
0
Sulfuric (Conc)
150
*
98
90
0
Bromine (Anhy)
59
23
7
90
90
1.2
Bromine (Anhy)
59
57
7
99
100
Bromine (Anhy)
59
57
30
94
93
3.4
Chlorine (Anhy)
120
7
85
84
7
Ammonium Hydroxide
66
7
97
97
0
Potassium Hydroxide (20%)
100
7
100
100
0
Sodium Hydroxide (50%)
120
7
94
80
0.2
23
7
99
98
0
Ferric Chloride (25%)
104
100
7
95
95
0
Zinc Chloride (25%)
104
100
7
100
100
0
Sulfuryl Chloride
68
68
7
86
100
8
Phosphoric Trichloride
75
75
7
100
98
Phosphoric Oxychloride
104
104
7
100
100
Silicon Tetrachloride
60
60
7
100
100
Water
100
100
7
100
100
0
Skydrol
149
7
100
95
3.0
Aerosafe
149
7
92
93
3.9
A-20 Stripper Solution
140
7
90
90
Chemical
Halogens
Bases
Peroxides Hydrogen Peroxide (30%) Salt-Metal Etchants
Other Inorganics
Miscellaneous
*Exposed for 6 hours. NOTES: Change in properties of 15% is considered insignificant. Samples were 1015 mil microtensile bars. TS/E and wt. gain determined within 24 hours after removal from exposure media.
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
355 Table 12.9. Hydrolytic Stability of ETFE to Boiling Water[8] Length of Exposure, Hours
Resin Unfilled ETFE
Filled ETFE (containing 25% weight glass fiber)
Tensile Strength, MPa
Elongation, %
0
40
145
3,000
40
135
0
82
7
1,000
60
5
2,000
57.6
5
3,000
55.8
5
Table 12.10. Chemical Compatibility of Polyvinylidene Fluoride (PVDF)[9]
Chemical Substance
Concentration
Maximum Temp., °C
A
Chemical Substance
Concentration
Maximum Temp., °C
Aluminum Acetate
Aqueous solution or solid
135
Acetaldehyde
NR
Acetamide
25
Aluminum Bromide
Acetic Acid
50
Aluminum Chloride
Up to 40% in water
135
Aqueous solution or solid
135
Acetic Acid
10% in water
110
Acetic Acid
50% in water
95
Aluminum Fluoride
Acetic Acid
80% in water
80
Acetic Anhydride
NR
Aluminum Hydroxide
Acetone
NR
Aluminum Nitrate
Acetone
10% in water
50
135
135 Aqueous solution or solid
Aluminum Oxychloride
135 135
Acetonitrile
50
Acetophenone
NR
Acetyl Bromide
50
Acetyl Chloride
50
Ammonia, Gas
NR
Acetylacetone
NR
Ammonia, Liquid
NR
Acetylene
120
Acrylonitrile
25
Adipic Acid
65
Air
140
Aluminum Sulfate
Aqueous solution or solid
135
Ammonium Acetate
Aqueous solution or solid
80
Ammonium Alum
Aqueous solution or solid
135
95
Ammonium Bifluoride
Aqueous solution or solid
65
Allyl Alcohol
50
Ammonium Bromide
Aqueous solution or solid
120
Allyl Chloride
100
Ammonium Carbonate
Aqueous solution or solid
135
Alcoholic Spirits
© Plastics Design Library
40% Ethyl Alcohol
Ch. 12: Chemical Properties of Fluoropolymers
356 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Ammonium Chloride
Aqueous solution or solid
135
Barium Sulfate
135
Ammonium Dichromate
Aqueous solution or solid
Barium Sulfide
135
120
Beer
95
Ammonium Fluoride
Aqueous solution or solid
135
Beet Sugar Liquors
110
Benzaldehyde
20
Ammonium Hydroxide
Up to concentrated
110
Benzene
75
Ammonium Metaphosphate
Aqueous solution or solid
135
Ammonium Nitrate
Aqueous solution or solid
135
Ammonium Persulfate
Aqueous solution or solid
25
Ammonium Phosphate
Aqueous solution or solid
135
Ammonium Sulfate
Aqueous solution or solid
135
Ammonium Sulfide
Aqueous solution or solid
50
Ammonium Thiocyanate
Aqueous solution or solid
135
Amyl Acetate
50
Amyl Alcohol
135
Sec-Amyl Alcohol
50
Amyl Chloride
135
Aniline
50
Aniline Hydrochloride
Aqueous solution or solid
Aqua Regia Arsenic Acid
25 25
Aqueous solution
Asphalt
135 120
B Barium Carbonate Barium Chloride
135 Aqueous solution or solid
Barium Hydroxide Barium Nitrate
135 135
Aqueous solution or solid
135
Chemical Substance
Benzenesulfonic Acid
Aqueous solution or solid
Maximum Temp., °C
50
Benzoic Acid
110
Benzoyl Chloride
75
Benzoyl Peroxide
75
Benzyl Alcohol
120
Benzyl Chloride
135
Benzyl Ether
40
Benzylamine
Aqueous solution or liquid
25
Black Liquor
80
Bleaching Agents
135
Borax
135
Boric Acid
135
Boron Trifluoride
25
Brine
135
Brine, acid
135
Brine, basic
135
Brine, chlorinated acid
95
Bromic Acid
Aqueous solution
95
Bromine dry gas
65
Bromine, liquid
65
Bromine, Water
100
Bromobenzene
65
Bromoform
65
m-Bromotoluene
80
Butadiene
120
Butane
120
Butanediol
Ch. 12: Chemical Properties of Fluoropolymers
Concentration
Aqueous solution or
135
© Plastics Design Library
357 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Chemical Substance
Concentration
Maximum Temp., °C
25
Calcium Hydroxide
Aqueous solution or liquid
110
Calcium Hypochlorite
Aqueous solution or solid
95
Aqueous solution or solid
135
sec-Butyl Alcohol
Aqueous solution or liquid
Calcium Nitrate 95
t-Butyl Alcohol
Aqueous solution or liquid
95
Butyl Acetate Butyl Alcohol
135
Calcium Oxide
120
Calcium Phosphate
135
Calcium Sulfate
135
Cane Sugar Liquors
135
Butyl Acrylate
50
Caprylic Acid
80
Butyl Bromide
135
Carbon Dioxide
135
Butyl Chloride
135
Carbon Disulfide
25
Butyl Ether
40
Carbon Monoxide
135
Butyl Mercaptan
135
Carbon Tetrachloride
135
Butyl Stearate
40
Carbonic Acid
135
Casein
135
Castor Oil
135
Chloral Hydrate
25
Chlorinated Phenol
65
Butylamine
Aqueous solution or liquid
NR
sec-Butylamine
Aqueous solution or liquid
20
Aqueous solution or solid
20
t-Butylamine
5% in CCl4
Chlorine
95
Chlorine, gas
95
Chlorine, liquid
95
1-Butylene
135
Chlorine Dioxide
65
Butylphenol
110
Chlorine Water
110
Butyraldehyde
65
Butyric Acid
110
C
Chloroacetic Acid
Aqueous solution or pure
NR
Chloroacetyl Chloride
50 75
Calcium Acetate
Aqueous solution or solid
135
Chlorobenzene
Calcium Bisulfate
Aqueous solution or solid
135
Chlorobenzenesulfonic Acid
Calcium Bisulfite
Aqueous solution or solid
135
Chlorobenzyl Chloride
50
Calcium Bromide
Aqueous solution or solid
135
Chlorofluorocarbon 11
95
135
Chlorofluorocarbon 12
95
Chlorofluorocarbon 13
95
Calcium Carbonate Calcium Chlorate
Aqueous solution or solid
135
Calcium Chloride
Aqueous solution or solid
135
© Plastics Design Library
Aqueous solution or pure
95
Ch. 12: Chemical Properties of Fluoropolymers
358 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Chlorofluorocarbon 14
95
Chlorofluorocarbon 21
95
Chlorofluorocarbon 22
95
Chlorofluorocarbon 113
95
Chlorofluorocarbon 114
95
Chloroform
50
6-Chlorohexanol
75
Chlorohydrin
50
Chloropicrin
65
Chlorosulfonic Acid
NR
Chlorotrimethylsilane
50
Chrome Alum
Aqueous solution or solid
95
Chromic Acid
Up to 40% in water
80
Chromic Acid
50% in water
Chemical Substance
Concentration
Maximum Temp., °C
Corn Syrup
120
Cottonseed Oil
135
Cresol
65
Cresylic Acid
65
Crotonaldehyde
50
Crude Oil
135
Cryolite
120
Cuprous Chloride
120
Cyclohexane
135
Cyclohexanol
65
Cyclohexanone
25
Cyclohexyl Acetate
95
D Decane Dextrin
120 Aqueous solution or solid
120
Diacetone Alcohol
25
p-Dibromobenzene
95
1,2-Dibromopropane
95
50
Dibutyl Phthalate
NR
Chromyl Chloride
50
Dibutyl Sebacate
NR
Cider
60
Citric Acid
Aqueous solution or solid
135
Coal Gas
110
Coconut Oil
135
Copper Acetate
Aqueous solution or solid
Copper Carbonate, basic Copper Chloride
120 135
Aqueous solution or solid
135
Copper Cyanide
135
Copper Fluoride
135
Copper Nitrate Copper Sulfate
Aqueous solution or solid
135
Aqueous solution or solid
135
Corn Oil
Ch. 12: Chemical Properties of Fluoropolymers
Dibutylamine
Aqueous solution or liquid
20
Dichloroacetic Acid
Aqueous solution or liquid
50
o-Dichlorobenzene
65
Dichlorodimethylsilane
50
Dichloroethylene
110
2,2-Dichloropropionic Acid
50
==-Dichlorotoluene
65
Diesel Fuels
135
Diethanolamine
Aqueous solution or liquid
NR
135
© Plastics Design Library
359 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Aqueous solution or liquid
25
Chemical Substance
Concentration
Maximum Temp., °C
Ethyl Acetate
NR
Ethyl Acetoacetate
25
NR
Ethyl Acrylate
25
50
Ethyl Alcohol
Diglycolic Acid
25
Ethyl Chloride
135
Diisobutyl Ketone
95
Ethyl Chloroacetate
25
Diisobutylene
135
Ethyl Chloroformate
50
Diisopropyl Ketone
20
Ethyl Cyanoacetate
25
Dimethyl Acetamide
NR
Ethyl Ether
50
Dimethyl Formamide
NR
Ethyl Formate
25
Dimethyl Phthalate
25
Ethylbenzene
50
Dimethyl Sulfate
25
Diethylamine Diethyl Malonate Diethylenetriamine
Aqueous solution or liquid
Dimethyl Sulfoxide Dimethylamine
Aqueous soluton or gas
25
Ethylene Chlorohydrin
Ethylene Glycol
25
2,6Dimehyl-4heptanol
95
2,5-Dimethyl-1,5hexadiene
120
Dioctyl Phthalate
25
1,4,1,4-Dioxane
NR
2-Ethyl-1-hexanol
Dioxolane
NR
F
Dipropylene Glycol Methyl Ether
25
Disodium Phosphate Divinyl Benzene
95 50
E NR Aqueous solution or solid
Ethanethiol
80 25
Ethanolamine
Aqueous solution or liquid
NR
2-Ethoxyethyl Acetate
Aqueous solution or liquid
95
© Plastics Design Library
Aqueous solution or liquid
Ethylene Oxide Ethylenediamine
135
25 135 135 NR
Aqueous solution or liquid
110 120
Fatty Acids
135
Fatty Acids, Sulfonates
80
Ferric Chloride
Aqueous solution or solid
Ferric Hydroxide
Epichlorohydrin Epsom Salts
Aqueous solution or liquid
Ethylene Dichloride
Dimethylaniline
Aqueous solution or solid
Aqueous solution or liquid
Ferric Nitrate
135 120
Aqueous solution or solid
135
Ferric Sulfate
135
Ferric Sulfide
120
Ferrous Chloride
Aqueous solution or solid
Ferrous Hydroxide Ferrous Nitrate
135 120
Aqueous solution or solid
135
Ch. 12: Chemical Properties of Fluoropolymers
360 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Chemical Substance
Concentration
Maximum Temp., °C
Ferrous Sulfate
135
H
Fluorine
25
Heptane
135
135
Hexachloro-1,3butadiene
50
135
Fluoroboric Acid
Aqueous solution
Fluorosilic Acid Formaldehyde Formic Acid Fructose
37% in water
50
Hexamethylenediamine
NR/50
Aqueous solution or liquid
120
Hexamethylphosphotriamide
NR
Aqueous solution or solid
Hexane
135
135
Hexyl Alcohol
80
Fruit Juices, pulp
95
Fuel Oil
135
Fumaric Acid
65
Furan
NR
Furfural
25
Furfuryl Alcohol
Aqueous solution or liquid
Aqueous solution or liquid
95
Aqueous solution or solid
25
Aqueous solution or liquid
50
Aqueous solution
135
Hydrobromic Acid
Up to 50% in water
135
Hydrochloric Acid
Up to concentrated
135
Hydrocyanic Acid
Aqueous solution
135
Hydrofluoric Acid
Up to 40% in water
120
41100% in water
95
Hydrazine Hydrazine Dihydrochloride Hydrazine Hydrate
40
Hydriodic Acid
G Gallic Acid
25
Gas, manufactured
135
Gas, natural
135
Gasoline, leaded
135
Gasoline, sour
135
Gasoline, unleaded
135
Gelatin
120
Gin
95
Hydrofluoric Acid
135
Hydrogen
135
Glue
120
Hydrogen Chloride
135
Glutamic Acid
95
Hydrogen Cyanide
135
Hydrogen Fluoride
95
Glucose
Aqueous solution or solid
Glycerin
Aqueous solution or liquid
135
Glycine
Aqueous solution or solid
25
Glycolic Acid
25
Hydrogen Peroxide
Up to 30% in water
95
Hydrogen Peroxide
90% in water
20
Hydrogen Sulfide Hydrogen Sulfide
135 Aqueous solution
Hydroquinone Hypochlorous Acid
Ch. 12: Chemical Properties of Fluoropolymers
110 120
Aqueous
20
© Plastics Design Library
361 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
I Iodine
10% in Nonaqueous solvent
Chemical Substance Lithium Chloride
65 65
M
Iodoform
95
Isoamyl Ether
120
Magnesium Carbonate
Isobutyl Alcohol
120
Isooctane
120
Isophorone
80
Isopropyl Alcohol
60
Isopropyl Chloride
40
Isopropyl Ether
50
Isopropylbenzene
40
J Jet Fuel (JP4, JP5)
95
K Kerosene
135
L Lactic Acid
Aqueous solution or pure
50
Maximum Temp., °C
Aqueous solution or solid
120
Lubricating Oil
Iodine, gas
Aqueous solution or liquid
Concentration
Magnesium Chloride
135
135 Aqueous solution or solid
135
Magnesium Citrate
120
Magnesium Hydroxide
135
Magnesium Nitrate
Aqueous solution or solid
135
Magnesium Sulfate
Aqueous solution or solid
135
Maleic Acid
Aqueous solution or solid
120
Maleic Anhydride
25
Malic Acid
Aqueous solution or solid
120
Manganese Sulfate
Aqueous solution or solid
120
Mercuric Chloride
120
Mercuric Cyanide
120
Lanolin
120
Lard Oil
135
Lauric Acid
110
Mercury
135
Lauroyl Chloride
120
Methacrylic Acid
50
Lauryl Mercaptan
95
Methane
135
Lauryl Sulfate
120
Methanesulfonic Acid
Lead Acetate
Aqueous solution or solid
Lead Chloride Lead Nitrate
135 120
Aqueous solution or solid
120
Lemon Oil
120
Linoleic Acid
120
Linseed Oil
135
Lithium Bromide
© Plastics Design Library
110
Aqueous solution or solid
Aqueous solution or liquid
135
95
Methyl Acetate
40
Methyl Acrylate
40
120
Lead Sulfate
Aqueous solution or solid
Mercuric Nitrate
Methyl Alcohol
Aqueous solution or liquid
135
Methyl Bromide
135
Methyl Chloride
135
Methyl Chloroacetate
25
Methyl Chloromethyl Ether
25
Ch. 12: Chemical Properties of Fluoropolymers
362 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Chemical Substance
Concentration
Maximum Temp., °C
Methyl Ethyl Ketone
NR
Nitroethane
20
Methyl Isobutyl Ketone
NR
Nitrogen
135
Methyl Methacrylate
50
Nitrogen Dioxide
75
Methyl Salicylate
65
Nitroglycerin
50
Methylamine
NR
Nitromethane
50
Methylchloroform
50
Nitrotoluene
80
Methylene Bromide
80
Nitrous Oxide
NR
Methylene Chloride
NR
Methylene Iodine
95
Methylsufuric Acid
Aqueous solution or liquid
50
Methyltrichlorosilane
65
Milk
110
Mineral Oil
135
Motor Oil
135
Molasses
65
Morpholine
Aqueous solution or liquid
25
N Naphtha
135
Naphthalene
95
Nickel Acetate
Aqueous solution or solid
120
Nickel Chloride
Aqueous solution or solid
Nickel Nitrate Nickel Sulfate
O Octane
135
Octene
135
Oleic Acid
120
Oleum
NR
Olive Oil
120
Oxalic Acid
50
Oxygen
135
Ozone
110
P Palm Oil
95
Palmitic Acid
120
Paraffin
120
Paraffin Oil
120
Peanut Oil
120
Perchloric Acid
10% in water
95
Perchloric Acid
70% in water
50
Perchloroethylene
135
135
Perchloromethyl Mercaptan
50
Aqueous solution or solid
135
Petrolatum
135
Aqueous solution or solid
Petroleum
120
135
Phenol
80
Phenol
50
120
1-Phenol-2-sulfonic Acid
50
Phenyl Ether
50
Phenylhydrazine
50
Nicotine
20
Nicotinic Acid Nitric Acid
Up to 10% in water
50
Nitric Acid
11-50% in water
50
Nitric Acid
Concentrated
NR
Nitric Acid, fuming
NR
Nitrobenzene
25
Ch. 12: Chemical Properties of Fluoropolymers
5% in water
Phenylhydrazine Hydrochloride
Aqueous solution or solid
50
o-Phenylphenol
80
Phosgene
80
© Plastics Design Library
363 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Phosphoric Acid
Less than 85% in water
135
Phosphoric Acid
85% in water
110
Chemical Substance Potassium Acetate Potassium Alum
Concentration
Maximum Temp., °C
Aqueous solution or solid
135
Aqueous solution or liquid
135
Phosphorus, red
25
Phosphorus, Oxychloride
NR
Potassium Aluminum Chloride
Phosphorus, Pentachloride
95
Potassium Bicarbonate
Aqueous solution or solid
95
Phosphorus, Pentoxide
95
Potassium Bisulfate
Aqueous solution or solid
135
Phosphorus, Trichloride
95
Potassium Borate
Aqueous solution or solid
135
Phthalic Acid
95
Picric Acid
25
Potassium Bromate
Aqueous solution or solid
135
Potassium Bromide
Aqueous solution or solid
135
Potassium Carbonate
Aqueous solution or solid
135
Plating Solutions: Brass Plating Solutions: Cadmium Plating Solutions: Chrome Plating Solutions: Copper Plating Solutions: Iron Plating Solutions: Lead Plating Solutions: Nickel Plating Solutions: Rodium Plating Solutions: Silver Plating Solutions: Speculum Plating Solutions: Tin Plating Solutions: Zinc
95 95 95
95 95 95 95
95
Potassium Chloride
Aqueous solution or solid
135
Potassium Chromate
Aqueous solution or solid
135
Potassium Cyanide
Aqueous solution or solid
135
95 Potassium Dichromate
135
Potassium Ferricyanide
Aqueous solution or solid
135
Potassium Ferrocyanide
Aqueous solution or solid
135
Potassium Fluoride
Aqueous solution or solid
135
95
Potassium Hydroxide
Up to 10% in water
85
95
Potassium Hydroxide
Greater than 50% in water
NR
Aqueous solution
95
Potassium Iodide
Aqueous solution or solid
120
Potassium Nitrate
Aqueous solution or solid
135
Polyethylene Glycol
95
Polyvinyl Acetate
135
Polyvinyl Alcohol
135
Potassium
NR
© Plastics Design Library
Potassium Chlorate
95
95
135
Potassium Hypochlorite
Ch. 12: Chemical Properties of Fluoropolymers
364 Table 12.10. (Contd.)
Maximum Temp., °C
Chemical Substance
Concentration
Maximum Temp., °C
Sodium Benzoate
Aqueous solution or solid
135
Sodium Bicarbonate
Aqueous solution or solid
135
Sodium Bisulfate
Aqueous solution or solid
135
135
Sodium Bisulfite
Aqueous solution or solid
135
Potassium Sulfide
135
Propane
135
Sodium Bromate
Aqueous solution or solid
95
Propyl Acetate
40
Sodium Bromide
Aqueous solution or solid
135
65
Sodium Carbonate
Aqueous solution or solid
135
Propylamine
NR
Sodium Chlorate
120
Propylene Dibromide
Aqueous solution or solid
95
Sodium Chlorite
120
Propylene Dichloride
95
Aqueous solution or solid
Sodium Chromate
Aqueous solution or solid
95
Sodium Cyanide
Aqueous solution or solid
135
Chemical Substance
Concentration
Potassium Perborate
135
Potassium Perchlorate
95
Potassium Permanganate
Aqueous solution or solid
Potassium Persulfate Potassium Sulfate
Propyl Alcohol
Propylene Glycol
120 50
Aqueous solution or solid
Aqueous solution or liquid
Aqueous solution or liquid
65
Propylene Oxide
NR
Pyridine
NR
Sodium Dichromate
Aqueous solution or solid
95
50
Sodium Dithionite
Aqueous solution or solid
40
Salicylaldehyde
50
Sodium Ferricyanide
Aqueous solution or solid
135
Salicylic Acid
95
Sodium Ferrocyanide
Aqueous solution or solid
135
Sodium Fluoride
Aqueous solution or solid
135
Pyrogallol
Aqueous solution or solid
S
Selenic Acid
Aqueous solution or pure
65
Silicon Tetrachloride
50
Silicone Oil
120
Sodium Fluosilcate
Silver Cyanide
135
Sodium Hydrogen Phosphate
Aqueous solution or solid
120
Sodium Hydroxide
Up to 10% in water
85
Sodium Hydroxide
Greater than 50% in water
NR
Sodium Hypochlorite
Up to 5% in water
135
Sodium Hypochlorite
615% in water
95
Silver Nitrate
Aqueous solution or solid
135
Silver Sulfate
120
Sodium
NR
Sodium Acetate
Aqueous solution or solid
Sodium Amalgam
Ch. 12: Chemical Properties of Fluoropolymers
135 NR
95
© Plastics Design Library
365 Table 12.10. (Contd.)
Concentration
Maximum Temp., °C
Sodium Iodide
Aqueous solution or solid
135
Sodium Nitrate
Aqueous solution or solid
135
Sodium Nitrite
Aqueous solution or solid
Chemical Substance
Sodium Palmitate Sodium Perchlorate
Aqueous solution or solid
Sodium Peroxide
Chemical Substance
Concentration
Maximum Temp., °C
T Tall Oil
135
Tallow
135
Tannic Acid
110
135
Tar
120
120
Tartaric Acid
120
1,1,2,2-Tetrabromoethane
120
1,1,2,2-Tetrachloroethane
120
2,3,4,6-Tetrachlorophenol
65
Tetraethyllead
135
95
Sodium Phosphate
Aqueous solution or solid
135
Sodium Thiocyanate
Aqueous solution or solid
120
Sodium Thiosulfate
Aqueous solution or solid
135
Sour Crude Oil
135
Soybean Oil
120
Stannic Chloride
Aqueous solution or liquid
135
Stannous Chloride
Aqueous solution or solid
135
Tetrahydrofuran Tetramethylammonium Hydroxide
Aqueous solution or solid
120
Aqueous solution or liquid
NR
Up to 10% in water
95
Tetramethylurea
NR
Thioglycol
25
Thioglycolic Acid
80
Starch
95
Thionyl Chloride
NR
Stearic Acid
135
Stilbene
80
Thiophosphoryl Chloride
NR
Styrene
85
Thread Cutting Oils
95
Succinic Acid
65
65
Sugar Syrup
135
Titanium Tetrachloride
Sulfur
120
Toluene
80
Sulfur Chloride
25
Toluenesulfonyl Chloride
50
Sulfur Dichloride
25
Tomato Juice
95
Sulfur Dioxide
80
Tributyl Phosphate
25
Sulfur Trioxide
NR
Sulfuric Acid Sulfuric Acid Sulfuric Acid Sulfuric Acid, fuming Sulfuryl Chloride Sulfuryl Fluoride
© Plastics Design Library
Up to 60% in water
120
8093% in water 98% in water
95 65 NR NR 25
Trichloroacetic Acid
Up to 10% in water
95
Trichloroacetic Acid
50% in water to pure
50
1,2,4-Trichlorobenzene
95
1,1,2-Trichloroethane
65
Trichloroethylene
135
Ch. 12: Chemical Properties of Fluoropolymers
366 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
2,4,5Trichlorophenol
65
Tricresyl Phosphate
NR
Triethanolamine
Aqueous solution or liquid
50
Triethyl Phosphate
NR
Triethylamine
50
Trifluoroacetic Acid
50% in water
Trifluoroacetic Acid Trimethylamine
95 50
Aqueous solution or gas
Turpentine
65 135
U Urea
Aqueous solution or solid
120
V Varnish
120
Varsol
120
Vegetable Oil
135
Vinegar
110
Vinyl Acetate
120
Ch. 12: Chemical Properties of Fluoropolymers
Chemical Substance
Concentration
Maximum Temp., °C
Vinyl Chloride
95
Vinylidene Chloride
95
W Water
135
Water, salt
135
Water, sewage
120
Whiskey
95
Wine
95
X Xylene
95
Z Zinc Acetate
Aqueous solution or solid
120
Zinc Bromide
Aqueous solution or solid
120
Zinc Chloride
Aqueous solution or solid
135
Zinc Nitrate
Aqueous solution or solid
135
Zinc Sulfate
Aqueous solution or solid
135
© Plastics Design Library
367 Table 12.11. Chemical Compatibility of Ethylene-Chlorotrifluoroethylene Copolymer[10] Retained Properties Test Temp., °C
Tensile Strength
Elongation
Weight Gain, %
Color Change
Acetic Acid
140
I
I
3.4
1
Ammonium Hydroxide, 30%
140
I
I
1.2
2
Butanol n
121
I
I
1.9
1
Chromic Acid, 30%
100
I
I
0.0
2
Hydrochloric Acid, 37%
100
I
I
0.7
3
Hydrofluoric Acid, 49%
100
I
I
0.2
2
Hydrogen Peroxide (60%)
30
I
I
0.3
1
Methanol
50
I
I
0.4
1
n-Methylpyrrolidone
20
I
I
1.5
1
Methylene Chloride
50
I
I
4.1
1
Nitric Acid, 10%
121
I
I
0.4
1
Nitric Acid, 90%
71
I
I
2.3
2
Phosphoric Acid, 85%
140
I
I
-0.1
2
Potassium Hydroxide, 50%
121
I
I
-0.1
2
Propanol *
50
I
I
0.16
1
Sodium Hydroxide, 50%
132
I
I
-0.2
2
Sodium Hypochlorite, 5%
121
I
I
0.1
1
Sulfuric Acid, 98%
121
I
I
0.7
3
Toluene
20
I
I
0.7
1
Chemical Name
* tested for 28 days; all others tested at 30 days. Values are comparable. LEGEND RETAINED PROPERTIES:
COLOR CHANGE:
I Insignificant
1- no change 2- any shade of tan 3- brown or black
Table 12.12. Room Temperature Swelling of PVF in Organic Solvents[11]
Solvent
Swelling, wt%
Ethanol
4.8
Acetone
7.0
Dimethyl Formamide
32.3
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
368 In its simplest form, permeation can be expressed as a product of the solubility and diffusion coefficient of the permeant in the polymer. Permeation of a gas can be calculated from Eq. 12.1. This equation is derived from Ficks first law of mass transfer. Permeation concerns the movement of a species through the molecules of another species, e.g., a gas through a polymer. It does not take into account transport of material through cracks, voids, and in general physical flaws in the structure of the second species such as the polymer. To be sure, both phenomenon result in the migration of chemicals through the structure. This means that after an appropriate plastic material has been selected to meet the permeation requirements of a process, the equipment must be fabricated carefully to avoid flaws in the polymer structure. Eq. (12.1)
P=D·S
P (cm3/sec·cm·atm) is the permeability of the gas, D is the diffusion coefficient (cm3/sec), and S (cm3/cm3·atm) is the solubility coefficient. Several factors affect the permeation rate of the polymer. Temperature increase raises the permeation rate for two reasons. First, solubility of the permeant increases in the polymer at higher temperatures. Second, polymer chain movements are more abundant which allow easier diffusion of the permeant. The permeation rate of gases increases at higher partial pressures. For liquids, permeation rates rise with an increase in the concentration of the permeant. Unless the permeant species are highly soluble in the polymer, the permeation rate increases linearly with pressure, concentration, and the area of permeation. The permeation rate decreases at higher thickness, as illustrated in Fig. 12.3 for water transmission through a perfluorinated ethylene propylene copolymer (FEP). The effect of thickness is usually nonlinear. The permeation rate is very high at a low thickness and rapidly decreases with an increase in the thickness. After a critical thickness is reached, the effect of thickness is diminished and the permeation rate reaches a plateau. At lower thicknesses, the effect of surface structure begins to play a significant role in the permeation. A more oriented (ordered) surface will serve to inhibit permeation. Chemical and physical characteristics of the polymer have powerful effects on the rate of permeation, as much as four orders of magnitude.[12] Chemical affinity for the permeant, intermolecular forces such as van der Waals and hydrogen bonding forces, degree of
Ch. 12: Chemical Properties of Fluoropolymers
crystallinity, and degree of cross-linking are the influential variables. A similarity of chemical functional structures of the polymer and the permeant will promote solubility and permeation rate. Higher intermolecular forces of the polymer result in less permeation because of the resistance that they present to the development of space between adjacent molecules required for the passage of the permeant. Crystallinity is an important factor, which can be controlled during the processing of the polymer. The crystalline phase can be considered impermeable by most species because of its orderly structure (packing) which usually minimizes its specific volume. This means that there is little or no free space among the polymer chains for the passage of a permeant. The amorphous phase has the opposite construction and is disorderly with interchain space available for permeation. The specific volumes of the crystalline (0.43 cm3/g) and amorphous (0.5 cm3/g) phases of PTFE provide evidence for the argument. The amorphous phase has a 13% higher specific volume, which translates into additional space for permeation. Finally, cross-linking acts somewhat similar to crystallinity, though less effective, to limit space for permeation. Cross-linking is size-dependent and smaller species may permeate.
Figure 12.3 Water vapor transmission rate of Teflon® FEP resins at 40°C.[13]
© Plastics Design Library
369 The molecular size of the permeant, its chemical structure, and its condensation characteristics affect permeation. Diffusion of the permeant increases as its molecular size decreases, thus contributing to an increase in permeation. Molecular structure is important. A polar chemical will normally have a lower permeation rate in a nonpolar polymer than a nonpolar species and vice versa. This is due to the ability of chemicals with similar structures to the polymer to swell the polymer, that is, to create space between the chains for permeation. A more easily condensed chemical will also be more effective in swelling the polymer, resulting in higher rates of permeation.
12.5 Permeation Measurement and Data A number of methods can be used to measure permeation rate through polymers including fluoropolymers. These methods are helpful for comparison of different materials. The extent of the information obtained is limited due to the inability of these techniques
to account for real-world conditions. Typically, a film of fluoropolymer acts as a barrier to keep a gas or liquid in a reservoir. Figure 12.4 shows the schematic of a Thwing Albert cup for measuring liquid and vapor permeation. Permeation rate is calculated from the measured pressure or weight loss in the reservoir. Examples of techniques include ASTM Methods D 813 and F-739-81. There are more complex means of measuring permeation which approach the actual applications conditions. One example is a controlled recirculation of a fluid through a closed loop system which contains commercially manufactured parts made with the fluoropolymers, such as lined components. In these systems, gas chromatography and mass spectroscopy are used to analyze the permeation. A comparison of moisture vapor permeation through various polymers can be seen in Table 12.13. Notice that PCTFE is only second to FEP and both are among the most resistant plastics to water vapor permeation. Permeation data for gases and liquids through fluoroplastics are presented in Figs. 12.5 and 12.6. Permeability data can be found in Appendices IIV.
Figure 12.4 Schematics of a Thwing Albert cup for measuring liquid and vapor permeation.
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
370 Table 12.13. Permeation (Transmission) of Water and Gases through Polymer Films[15]
Water Vapor Transmission 2
Polymer Film
1
ACLAR® UltRx, SupRx, Rx
gm-mil 100 in /24 hrs @ 100°F @ 90% RH
cc (STP) mil/100 in2/24 hr-ATM @ 77°F
(gm-mm/m2/24 hrs @ 37.8°C @ 90% RH)
(cc [STP]-mm/m2/24 hr-ATM @ 25°C)
O2
N2
CO2
0.016
7
1
14
(0.006)
(2.8)
(0.4)
(5.5)
0.020
7
1
16
(0.008)
(2.8)
(0.4)
(6.3)
0.026
15
2.5
40
(0.010)
(5.9)
(1.0)
(15.7)
0.027
12
2.5
30
(0.011)
(4.7)
(1.0)
(12.0)
0.200.6
0.86.9
0.121.5
3844
(0.080.24)
(0.32.7)
(0.050.6)
(1517)
1.01.5
500
180
2700
(0.390.59)
(195)
(71)
(1060)
0.7
250535
85315
1002500
(0.28)
(100210)
(35125)
(40985)
0.3
185
42
580
(0.12)
(73)
(17)
(230)
1920
2.6
0.9
4.7
(7.57.9)
(1.0)
(0.35)
(1.9)
0.22
715
320
1670
(0.008)
(281)
(125)
(660)
2.1
7.5
0.25
11
(0.81)
(3)
(0.10)
(4.3)
2.5
3.4
9
5.5
(1.0)
(1.34)
(3.5)
(2.2)
1.01.3
3.06.0
0.71.0
1525
(0.390.51)
(1.22.4)
(0.280.39)
(5.99.8)
ACLAR® 33C ®
ACLAR 22C ®
ACLAR 22A
PVC, PVDC Copolymer
Gas Transmission
Polyethylene Low Density Medium Density High Density CAPRAN® 77C (Nylon 6) Fluorinated Ethylene Propylene Polyvinyl Fluoride Polyvinylidine Fluoride
PolyesterPET Oriented 1ACLAR®
is made from polychlorotrifluoroethylene.
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
371
Figure 12.5 Effect of density of Teflon® FEP resins on their permeability to gases at 30°C.[13]
Figure 12.6 Permeability through PTFE and ETFE.[16]
12.6 Environmental Stress Cracking A weakness of many polymers is their tendency to fail at fairly low stress levels due to the impact of some hostile environments. This phenomenon is known as environmental stress cracking. Cracking occurs when the polymer is stressed for a long time under loads that are relatively small compared to the yield point of the material. A well-known example includes the failure of vulcanized natural rubber in the presence of ozone. It reacts with unsaturated hydrocarbons at the surface and, even when the elastomers are subjected to low stresses, cracks can
© Plastics Design Library
develop and lead to failure. Another example is stress cracking of polyolefins such as high-density polyethylene in the presence of surfactants. When polyethylene is held under stress in the presence of some detergents, its behavior changes from short time ductile failure at high stresses to brittle fracture at low stresses after relatively longer times with very small break elongations.[17] Even though environmental stress cracking must be considered in designing parts from fluoropolymers, it is not considered an extensive problem for this family of plastics. Permeation variables have a strong influence on stress cracking. Different fluoropolymers
Ch. 12: Chemical Properties of Fluoropolymers
372 differ in their propensity to environmental stress cracking, primarily based on their degree of crystallinity. Crystallinity can be lowered by adding a comonomer and varying its concentration. A higher comonomer content decreases the crystalline phase content of the polymer. Resin processing can affect crystallinity. Fast cooling (or quenching) at the end of the fabrication process serves to reduce crystalline content and increase amorphous content. Lowering the crystalline phase content of the part tends to increase resistance to stress cracking due to the increasing break elongation. Increasing the molecular weight of the polymer reduces its crystallinity and enhances its stress crack resistance. Longer chains have higher tensile strength, i.e., load-bearing ability. Chemicals with structures similar to the polymer tend to permeate and plasticize, thus, reducing its mechanical strength. Fluoropolymers can be permeated by small halogenated molecules, usually con-
taining chlorine and fluorine due to their similarity of structures. Environmental stress cracking effect of chemicals on polymers can be measured by exposing the polymer to the chemical under the desired conditions. Tensile properties of the exposed sample can then be measured. Any loss of elongation and tensile strength would indicate environmental stress cracking. Processing of the fluoropolymers plays an important role in minimizing the tendency to undergo stress crack resistance. Reducing crystallinity as much as possible and minimizing residual stresses lowers the tendency of a part to experience environmental stress cracking. These objectives can be achieved by reducing processing times and cool-down rates, and annealing. Another issue is the stress that a part experiences in application. Tensile loads cause less tendency for stress cracking than compressive loads. Fluoropolymer-lined equipment and parts are examples of objects which may contain residual stresses due to their design and/or fabrication.
References 1. High Performance Fluorpolymer Coatings & Linings, Ausimont Montedison Group, www.ausiusa.com, Pub. AWD-5, Nov. 1998. 2. Teflon® PTFE Fluoropolymer Resin, Properties Handbook, DuPont Co., Jul. 1996. 3. Teflon® Fluorocarbon Resin, Performance Guide for the Chemical Processing Industry, DuPont, Technical Bulletin No. E-21623-3. 4. Teflon® PFA Fluoropolymer Resin, Properties Handbook, DuPont Co., May 1997. 5. Vita, G., and Pozzoli, M., MFA: Technical Paper, A New Perfluoropolymer for Molding, Extrusion and Coating Applications, Ausimont S. p. A., Italy. 6. Exploring the Chemical Resistance of Teflon® Resins, The Journal of Teflon®, 3 No. 9, Nov./Dec. 1962. 7. TEFZEL® Fluoropolymer, Chemical Use Temperature Guide, DuPont Co., Apr. 1990. 8. TEFZEL® ETFE Fluoropolymer Resin, Properties Handbook, No. E-31301-5, DuPont Co., Jul. 1996. 9. KYNAR® Polyvinylidene Fluoride, Chemical Resistant Chart, Elf Atochem Corporation, Philadelphia, PA. 10. HALAR® ECTFE Fluoropolymer, Design Guide ECTFE, Ausimont Montedison Group, Thorofare, NJ, Jun. 1997. 11. Brasure, D. E., and Ebnesajjad, S., Vinyl Fluoride Polymers, in: Encyclopedia of Polymer Science and Engineering, 2nd ed., 17:468491, John Wiley & Sons, New York, 1989. 12. Imbalzano, J. F., Washburn, D. N., and Mehta, P. M., Basics of Permeation and Environmental Stress Cracking in Relation to Fluoropolymers, Technical Information, DuPont Co., No. H-24240-1, Nov. 1993.
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
373 13. Teflon® FEP Fluoropolymer Resin, Properties Handbook, DuPont Co., publication No. H-37052-3, Jan. 1998. 14. Fuel Alcohol Permeation Rates of Fluoropolymers, Fluoroplastics, and Other Fuel Resistant Materials, W. M. Stahl and R. D. Stevens, DuPont Co., SAE Technical Paper Series 920163, presented at Int. Cong. & Exp., Detroit, MI, February 2428, 1992, reprinted in Teflon®/Tefzel® Technical Information, publication No. H-38086, June 1992. 15. ACLAR® Barrier Films, Technical Bulletin SFI-14, Allied Signal Advanced Materials, Morristown, NJ. 16. Teflon® Fluorocarbon Resins in Chemical Service, J. Teflon®, Publ. by DuPont Co., Jan.Feb. 1970. 17. Young, R. J., and Lovell, P. A., Introduction to Polymers, 2nd ed., Chapman & Hall, London, 1991.
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
Figure 12.1 Chemical resistance of fluoropolymers.[1]
© Plastics Design Library
cal resistance of ETFE, ECTFE, and PVDF is generally inferior to that of perfluorinated polymers such as PFA and FEP.
12.2 Chemical Compatibility of Perfluoropolymers Perfluoropolymers such as PTFE, PFA, and FEP are by far the most chemically resistant among thermoplastics. Few substances chemically interact with these plastics. The exceptions among the commercially encountered materials include alkali metals, especially in a molten state, and gaseous fluorine at high temperatures and pressures. Perfluoropolymers are attacked by certain halogenated compounds containing fluorine such as chlorine trifluoride (ClF3), bromine trifluoride, iodine pentafluoride, and oxygen difluoride (OF2). The inertness of these polymers arises from their molecular structure.[2] A few chemicals have been reported to attack perfluoropolymers at or near their upper service temperature (260°C).[3] They react with 80% sodium or potassium hydroxide. They also react with some strong Lewis bases including metal hydrides such as boranes (B2H6), aluminum chloride, ammonia, and some amines (RNH2) and imines (R=NH). Slow oxidative attacks may take place in the presence of 70% nitric acid at 250ºC under pressure. It is important to test the effect of these reagents on perfluoropolymers under the specific application temperature to determine the material limitations. Perfluoropolymers derive their chemical resistance from an extremely strong carbon-fluorine bond and an impermeable sheath of fluorine atoms surrounding the carbon-carbon chain. Relatively high crystalline content renders these polymers insoluble in solvents. Tables 12.1 and 12.2 summarize the effect of a number of representative organic and inorganic compounds on tetrafluoroethylene-perfluoropropyl vinyl ether polymer (PFA). Figure 12.2 gives a comparison of PFA and MFA (copolymer of tetrafluoroethylene and perfluoromethyl vinyl ether). Tables 12.312.6 summarize the effect of a number of representative organic and inorganic compounds on FEP.
Ch. 12: Chemical Properties of Fluoropolymers
338 Table 12.1. Effect of Immersion in Inorganic Chemicals for 168 hours on PFA.[4]
Exposure Temperature, ºC
Tensile Strength Retained, %
Elongation Retained, %
Weight Gain, %
Hydrochloric (conc.)
120
98
100
0
Sulfuric (conc.)
120
95
98
0
Hydrofluoric (60%)
23
99
99
0
Fuming Sulfuric
23
95
96
0
Aqua Regia
120
99
100
0
Chromic (50%)
120
93
97
0
Nitric (conc.)
120
95
98
0
Fuming Nitric
23
99
99
0
Ammonium Hydroxide (conc.)
66
98
100
0
Sodium Hydroxide (conc.)
120
93
99
0.4
23
93
95
0
Bromine
23
99
100
0.5
Bromine
59
95
95
-
Chlorine
120
92
100
0.5
Ferric Chloride
100
93
98
0
Zinc Chloride (25%)
100
96
100
0
Sulfuryl Chloride
69
83
100
2.7
Chlorosulfonic Acid
151
91
100
0.7
Phosphoric Acid (conc.)
100
93
100
0
Reagent Acids:
Oxidizing Acids:
Bases:
Peroxide: Hydrogen Peroxide (30%) Halogens:
Metal Salt Solutions:
Miscellaneous:
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
339 Table 12.2. Effect of Immersion in Organic Chemicals for 168 hours on PFA[4] Exposure Temperature, ºC
Tensile Strength Retained, %
Elongation Retained, %
Weight Gain, %
Glacial Acetic Acid
118
95
100
0.4
Acetic Anhydride
139
91
99
0.3
Trichloroacetic Acid
196
90
100
2.2
Isooctane
99
94
100
0.7
Naphtha
100
91
100
0.5
Mineral Oil
180
87
95
0
Toluene
110
88
100
0.7
O-Cresol
191
92
96
0.2
Nitrobenzene
210
90
100
0.7
205
93
99
0.3
66
88
100
0.7
Aniline
185
94
100
0.3
n-Butylamine
78
86
97
0.4
Ethylenediamine
117
96
100
0.1
179
90
99
0.5
Cyclohexanone
156
92
100
0.4
Methyl Ethyl Ketone
80
90
100
0.4
Acetophenone
202
90
100
0.6
Dimethylphthalate
220
98
100
0.3
n-Butylacetate
125
93
100
0.5
Tri-n-Butyl Phosphate
200
91
100
2.0
40
94
100
0.8
121
86
100
2.0
77
87
100
2.3
Dimethylformamide
154
96
100
0.2
Dimethylsulfoxide
189
95
100
0.1
Dioxane
101
92
100
0.6
Reagent Acids/Anhydrides:
Hydrocarbons:
Aromatic:
Alcohol: Benzyl Alcohol Ether: Tetrahydrofuran Amine:
Aldehyde: Benzaldehyde Ketone:
Esters:
Chlorinated Solvents: Methylene Chloride Perchloroethylene Carbon Tetrachloride Polar Solvents:
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
340
A:
Cylcohexanone @ 156ºC
B:
Toluene @ 110ºC
C:
Carbon tetrachloride @ 77ºC
D:
Dimethylformamide @ 40ºC
E:
Methylene chloride @ 40ºC
F:
Fuming nitric acid @ 23ºC
G: Fuming sulfuric acid @ 23ºC H:
Phosphoric acid 85% @ 100ºC
I:
MEK @ 80ºC
J:
Hydrogen peroxide 30% @ 23ºC
K:
Zinc chloride 25% @ 100ºC
L:
Ethylene diamine @ 117ºC
M: Sodium hydroxide @ 120ºC
Figure 12.2 A comparison of chemical resistance of PFA and MFA.[5]
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
341 Table 12.3. Chemical Resistance of FEP to Common Solvents[6]
Solvent
Acetone
Benzene
Carbon Terachloride
Ethanol (95%)
Ethyl Acetate
Toluene
© Plastics Design Library
Exposure Temperature, ºC
Exposure Time
Weight Gain, %
20
12 mo
0.3
50
12 mo
0.4
70
2 wk
0
78
96 hr
0.5
100
8 hr
0.6
200
8 hr
1.0
25
12 mo
0.6
50
12 mo
1.6
70
2 wk
1.9
100
8 hr
2.5
200
8 hr
3.7
25
12 mo
0
50
12 mo
0
70
2 wk
0
100
8 hr
0.1
200
8 hr
0.3
25
12 mo
0.5
50
12 mo
0.7
70
2 wk
0.7
25
12 mo
0.3
50
12 mo
0.6
70
2 wk
0.6
Ch. 12: Chemical Properties of Fluoropolymers
342 Table 12.4. Chemical Resistance of FEP to Common Acids and Bases[6] Reagent Hydrochloric Acid 10% 10% 10% 20% 20% Nitric Acid 10% 10% Sulfuric Acid 30% 30% 30% 30% Sodium Hydroxide 10% 10% 50% 50% Ammonium Hydroxide 10% 10%
Exposure Temperature, ºC
Exposure Time
Weight Gain, %
25 50 70 100 200
12 mo 12 mo 12 mo 8 hr 8 hr
0 0 0 0 0
25 70
12 mo 12 mo
0 0.1
25 70 100 200
12 mo 12 mo 8 hr 8 hr
0 0 0 0.1
25 70 100 200
12 mo 12 mo 8 hr 8 hr
0 0.1 0 0
25 70
12 mo 12 mo
0 0.1
Table 12.5. Chemical Compatibility of FEP with Halogenated Chemicals[6] Chemical
Effect on Polymer Sample
Chloroform
Wets, insoluble at boiling point
Ethylene Bromide
0.3% weight gain after 24 hr at 100°C
Fluorinated Hydrocarbons
Wets, swelling occurs in boiling solvent
Fluoro-naphthalene
Insoluble at boiling point, some swelling
Fluoronitrobenzene
Insoluble at boiling point, some swelling
Pentachlorobenzamide
Insoluble
Perfluoroxylene
Insoluble at boiling point, slight swelling
Tetrabromoethane
Insoluble at boiling point
Tetrachloroethylene
Wets, some swelling after 2 hr at 120°C
Trichloroacetic Acid
Insoluble at boiling point
Trichloroethylene
Insoluble at boiling point after 1 hr
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
343 Table 12.6. Chemical Compatibility of FEP with Various Chemicals[6]
Chemical
Effect on Polymer Sample
Abietic Acid
Insoluble at boiling point
Acetic Acid
Wets
Acetophenone
Insoluble 0.2% weight gain after 24 hr at 150°C
Acrylic Anhydride
No effect at room temperature
Allyl Acetate
No effect at room temperature
Allyl Methacrylate
No effect at room temperature
Aluminum Chloride
Insoluble in solution with NaCl; 15% anhydrous AlCl3 affects mechanical properties
Ammonium Chloride
Insoluble at boiling point
Aniline
Insoluble 0.3% weight gain after 24 hr at 150°C
Borax
No wetting or effect by 5% solution
Boric Acid
Insoluble at boiling point
Butyl Acetate
Insoluble at boiling point
Butyl Methacrylate
No effect at room temperature
Calcium Chloride
No effect by saturated solution in methanol
Carbon Disulfide
Insoluble at boiling point
Cetane
Wets, insoluble at boiling point
Chromic Acid
Insoluble at boiling point
Cyclohexanone
No effect observed
Dibutyl Phthalate
Wets, no effect at 250°C
Diethyl Carbonate
No effect at the room temperature
Dimethyl Ether
No effect observed
Dimethyl Formamide
No effect observed
Ethyl Ether
Wets
Ethylene Glycol
Insoluble at boiling point
Ferric Chloride
15% FeCl3·6H2O reduces mechanical properties
Ferric Phosphate
No effect by 5% solution
Formaldehyde
Insoluble at boiling point after 2 hr
Formic Acid
Insoluble at boiling point
Hexane
Wets
Hydrogen Fluoride
Wets, no effect by 100% HF at the room temperature
Lead
No effect
Magnesium Chloride
Insoluble at boiling point
Mercury
Insoluble at boiling point
Methacrylic Acid
No effect at the room temperature
Methanol
Wets
Methyl Methacrylate
Wets above melting point
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
344 Table 12.6. (Contd.) Chemical
Effect on Polymer Sample
Naphthalene
No effect
Nitrobenzene
No effect
2-Nitro-Butanol
No effect
Nitromethane
No effect
2-Nitro-2-Methyl Propanol
No effect
n-Octadecyl Alcohol
Wets
Phenol
Insoluble at boiling point
Phthalic Acid
Wets
Pinene
Wets, insoluble at boiling point
Piperidene
No effect, 0.30.5% weight gain after 24 hr at 106°C
Polyacrylonitrile
No effect
Potassium Acetate
Insoluble at boiling point
Pyridine
No effect
Stannous Chloride
No effect at melting point (246°C)
Sulfur
No effect at 445°C
Triethanolamine
Wets, no effect
Vinyl Methacrylate
No effect at the room temperature
Water
Insoluble at boiling point
Xylene
0.4% weight gain after 48 hr at 137°C
Zinc Chloride
No effect at melting point (260°C)
Another commercially significant perfluoropolymer is the copolymer of tetrafluoroethyleneperfluoromethylvinylether. It has chemical resistance characteristics similar to the other perfluoropolymers. Some halogenated solvents are absorbed by perfluoropolymers without any chemical interaction or degradation. The action is strictly physical and the removal of the absorbed species restores it to its original state. Too much absorption by a perfluoropolymer sample can be an indication of excessive porosity. A highly porous sample may appear blistered due to the expansion of vapors in the surface pores. A properly fabricated part does not exhibit blistering. Appendix I contains data about the effect of high temperature automotive fuels on the physical properties of fluoropolymers.
Ch. 12: Chemical Properties of Fluoropolymers
12.3 Chemical Compatibility of Partially Fluorinated Fluoropolymers Partially fluorinated fluoropolymers with commercial significance include ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF). The presence of hydrogen in these plastics lowers the fluorine content compared to perfluoropolymers, and renders them susceptible to some chemicals. This means that care must be taken in the selection of these polymers to insure compatibility of process fluids. ETFE has excellent resistance to a great many chemicals. It is somewhat affected by oxidizers, chlorinated solvents, ketones, and esters but resists acids, alkalis, and organic solvents. Table 12.7 lists chemicals and the suggested maximum use temperature.
© Plastics Design Library
345 Table 12.7. Chemical Compatibility of ETFE[7] Chemical A Acetaldehyde
Maximum Use Temperature, °C 95
Chemical
Maximum Use Temperature, °C
Ammonium Sulfide
150
Ammonium Thiocyanate
150
Acetamide
120
Amyl Acetate
120
Acetic Acid (50%)
110
Amyl Alcohol
150
Acetic Acid (Glacial)
120
Amyl Chloride
150
Acetic Anhydride
150
Aniline
110
Acetone
65
Aniline Hydrochloride (10%)
65
Acetone(50% H2O)
65
Anthraquinone
135
Acetonitrile
65
Anthraquinone-Sulfonic Acid
135
Antimony Trichloride
100
Acetophenone Acetylchloride
150 65
Aqua Regia
100
Acetylene
120
Arsenic Acid
150
Acetylene Tetrabromide
150
B
Acetylene Tetrachloride
150
Barium Carbonate
150
Barium Chloride
150
Acrylonitrile
65
Adipic Acid
135
Barium Hydroxide
150
Air
150
Barium Sulfate
150
Allyl Alcohol Allyl Chloride
100 100
Barium Sulfide Battery Acid
150 120
Aluminum Ammonium Sulfate
150
Benzaldehyde
100
Aluminum Chloride
150
Benzene
100
Aluminum Fluoride
150
Benzene Sulfonic Acid
100
Aluminum Hydroxide
150
Benzoic Acid
135
Aluminum Nitrate
150
Benzoyl Chloride
65
Aluminum Oxychloride
150
Benzyl Alcohol
150
Aluminum Potassium Sulfate
150
Benzyl Chloride
150
Amino Acids (H2O)
100
Bismuth Carbonate
150
Ammonia (Anhydrous)
150
Black Liquor
150
Ammonia (Aqueous 30%)
110
Bleach (12.5% Cl2)
100
Ammonium Bifluoride
150
Borax
150
Ammonium Bromide (50%)
135
Boric Acid
150
Ammonium Carbonate
150
Brine
150
Ammonium Chloride
150
Bromic Acid
120
Ammonium Dichromate
135
Bromine (Dry)
65
Ammonium Fluoride
150
Bromine Water (10%)
110
Ammonium Hydroxide
150
mono-Bromobenzene
100
Ammonium Nitrate (Conc.)
110
Bromoform
100
Ammonium Perchlorate
135
m-Bromotoluene
100
Ammonium Persulfate
150
Butadiene
120
Ammonium Phosphate
150
Butane
150
Ammonium Sulfate
150
Butanediol
135
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
346 Table 12.7. (Contd.) Chemical Butyl Acetate
Maximum Use Temperature, °C 110
Butyl Acrylate
110
n-Butyl Alcohol
150
sec-Butyl Alcohol
150
tert-Butyl Alcohol
150
n-Butylamine
50
sec-Butylamine
50
tert-Butylamine
50
di-n-Butyl Amine
110
tri-n-Butyl Amine
110
Butylene
150
Butyl Bromide
150
Butyl Chloride
150
Chemical
Maximum Use Temperature, °C
Chloral Hydrate
100
Chlorinated Brine
120
Chlorinated Phenol
100
Chlorine (Dry)
100
Chlorine (Wet)
120
Chlorine Dioxide
120
Chloroacetic Acid (50% H2O)
110
Chlorobenzene
100
Chlorobenzyl Chloride
65
Chloroform
100
Chlorohydrin (Liquid)
65
Chlorosulphonic Acid
25
Chromic Acid (50%)
65
Chromic Chloride
100
Chromyl Chloride
100
n-Butyl Mercaptan
150
Butyl Phenol
110
Butyl Phthalate
65
Butyraldehyde
100
Clorox Bleach Solution (5-1/2% Cl2)
100
Butyric Acid
120
Coal Gas
100
Copper Chloride
150
C Calcium Bisulfate
150
Copper Cyanide
150
Calcium Bisulfide
150
Copper Fluoride
150
Calcium Carbonate
150
Copper Nitrate
150
Calcium Chlorate
150
Copper Sulfate
150
Calcium Chloride
150
Cresol
135
Calcium Hydroxide
150
Cresylic Acid
135
Calcium Hypochlorite
150
Crotonaldehyde
100
Calcium Nitrate
150
Crude Oil
150
Calcium Oxide
135
Cyclohexane
150
Calcium Sulfate
150
Cyclohexanol
120
Calcium Sulfide
120
Cyclohexanone
150
Caprylic Acid
100
D
Carbon Dioxide (Dry)
150
DDT
Carbon Dioxide (Wet)
150
Decalin
120
Carbon Disulfide
65
Decane
150
Carbon Monoxide
150
Dextrin
150
Carbon Tetrachloride
135
Diacetone Alcohol
100
Carbonic Acid
150
1,2-Dibromopropane
95
Castor Oil
150
Dibutyl Phthalate
65
Caustic Potash (10 and 50%)
100
Dichloroacetic Acid
65
Caustic Soda (10 and 50%)
100
o-Dichlorobenzene
65
150
Dichloroethylene
65
Cellosolve
®
Ch. 12: Chemical Properties of Fluoropolymers
100
© Plastics Design Library
347 Table 12.7. (Contd.) Chemical Dichloropropionic Acid
Maximum Use Temperature, °C 65
Chemical
Maximum Use Temperature, °C
Ferric Hydroxide
150
150
Ferric Nitrate
150
Diethyl Benzene
135
Ferric Sulfate
150
Diethyl Cellosolve
150
Ferrous Chloride
150
Diethyl Ether
100
Ferrous Hydroxide
150
Diethylamine
110
Ferrous Nitrate
150
Diethylene Triamine
100
Ferrous Sulfate
150
Diglycolic Acid
100
Fluorine (Gaseous)
40
Diisobutyl Ketone
100
Fluoroboric Acid
135
Diisobutylene
135
Fluosilicic Acid
135
Dimethyl Formamide
120
Formaldehyde (37% in H2O)
110
Dimethyl Phthalate
100
Formic Acid
135
Dimethyl Sulfate
65
FREON 11
110
FREON 12
110
Diesel Fuels
Dimethyl Sulfoxide
100
® ® ®
Dimethylamine
50
FREON 22
110
Dimethylaniline
135
Fuel Oil
150
Dioctyl Phthalate
65
Fumaric Acid
95
p-Dioxane Diphenyl Oxide
65 80
Furane Furfural
65 100
Divinyl Benzene
80
G
E Epichlorhydrin
Gallic Acid
100
65
GasManufactured
150
Ether
100
GasNatural
150
Ethyl Acetate
65
GasolineLeaded
150
Ethyl Alcohol
150
GasolineSour
150
Ethylamine
40
GasolineUnleaded
150
Esters
65
Glycerol
150
Ethylacetoacetate
65
Glycol
135
Ethyl Acrylate
100
Glycolic Acid
120
Ethyl Chloride
150
H
Ethyl Chloroacetate
100
Heptane
150
Ethyl Cyanoacetate
100
Hexane
150
Ethylene Bromide
150
Hydrazine
40
Ethylene Chloride
150
Hydrazine Dihydrochloride
50
Ethylene Chlorohydrin
65
Hydriodic Acid
150
Ethylene Diamine
50
Hydrobromic Acid (50%)
150
Ethylene Glycol
150
Hydrochloric Acid (20%)
150
Ethylene Oxide
110
Hydrochloric Acid (Conc.)
150
F Fatty Acids
Hydrochloric Acid (Gas)
150
150
Hydrocyanic Acid
150
Ferric Chloride (50% in H2O)
150
Hydrofluoric Acid (35%)
135
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
348 Table 12.7. (Contd.) Chemical
Maximum Use Temperature, °C
Chemical
Maximum Use Temperature, °C 95
Hydrofluoric Acid (70%)
120
Maleic Anhydride
Hydrofluoric Acid (100%)
110
Malic Acid
135
Hydrofluorosilicic Acid
150
Mercuric Chloride
135
Hydrogen
150
Mercuric Cyanide
135
Hydrogen Cyanide
150
Mercuric Nitrate
135
Hydrogen Peroxide (30%)
120
Mercury
135
Hydrogen Peroxide (90%)
65
Methacrylic Acid
95
Hydrogen Phosphide
65
Methane
120
Hydrogen Sulfide (Dry)
150
Methane Sulfonic Acid (50%)
110
Hydrogen Sulfide (Wet)
150
Methyl Alcohol
150
Hydroquinone
120
n-Methylaniline
120
150
Methyl Benzoate
120
Hypochlorous Acid
Methyl Bromide
I
150 ®
Inert Gases
150
Methyl Cellosolve
Iodine (Dry)
110
Methyl Chloride
150
Iodine (Wet)
110
Methyl Chloroform
65
Iodoform
110
Methyl Chloromethyl Ether
80
Isobutyl Alcohol Isopropylamine
135 50
Methyl Cyanoacetate Methyl Ethyl Ketone
80 110
Methyl Isobutyl Ketone
110
J
150
Jet FuelJP4
110
Methyl Methacrylate
80
Jet FuelJP5
110
Methyl Salicylate
95
L
Methyl Sulfuric Acid
100
Lactic Acid
120
Methyl Trichlorosilane
95
Lard Oil
150
Methylene Bromide
100
Lauric Acid
120
Methylene Chloride
100
Lauryl Chloride
135
Methylene Iodide
100
Lauryl Sulfate
120
Mineral Oil
150
Lead Acetate
150
Monochlorobenzene
110
Linoleic Acid
135
Monoethanolamine
65
Linseed Oil
150
Morpholine
65
Lithium Bromide (Saturated)
120
Lithium Hydroxide
150
N Naphtha
150
Lubricating Oil
150
Naphthalene
150
M
Nickel Chloride
150
Magnesium Carbonate
150
Nickel Nitrate
150
Magnesium Chloride
150
Nickel Sulfate
150
Magnesium Hydroxide
150
Nicotine
100
Magnesium Nitrate
150
Nicotinic Acid
120
Magnesium Sulfate
150
Nitric Acid (50%)
65
Maleic Acid
135
Nitric Acid (Conc. 70%)
25
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
349 Table 12.7. (Contd.) Chemical
Maximum Use Temperature, °C
Chemical
Maximum Use Temperature, °C 150
Nitric AcidSulfuric Acid (50/50)
100
Potassium Aluminum Chloride
Nitrobenzene
150
Potassium Aluminum Sulfate (50%)
150
Nitrogen Dioxide
100
Potassium Bicarbonate
150
Nitrogen Gas
150
Potassium Borate
150
Nitromethane
100
Potassium Bromate
150
Nitrous Acid
100
Potassium Bromide
150
Potassium Carbonate
150
O Octane
150
Potassium Chlorate
150
Octene
150
Potassium Chloride
150
Oleic Acid
135
Potassium Chromate
150
Oleum
50
Potassium Cyanide
150
Oxalic Acid
110
Potassium Dichromate
150
Oxygen
150
Potassium Ferrocyanide
150
Ozone (<1% in Air)
100
Potassium Fluoride
150
Potassium Hydroxide (50%)
100
P Palmitic Acid
135
Potassium Hypochlorite
135
Perchlorethylene
135
Potassium Nitrate
150
Perchloric Acid (10%)
110
Potassium Perborate
135
Perchloric Acid (72%)
65
Potassium Perchlorate
100
Petrolatum
150
Potassium Permanganate
150
Petroleum
150
Potassium Persulfate
65
Petroleum Ether
100
Potassium Sulfate
150
Phenol (10%)
110
Potassium Sulfide
150
Phenol (100%)
100
Propane
135
Phenolsulfonic Acid
100
Propionic Acid
100
Phenylhydrazine
100
Propyl Alcohol
100
Phenylhydrazine Hydrochloride
100
Propylene Dibromide
100
o-Phenylphenol
100
Propylene Dichloride
100
Phosgene
100
Propylene Glycol Methyl Ether
100
Phosphoric Acid (30%)
150
Propylene Oxide
65
Phosphoric Acid (85%)
135
Pyridine
65
Phosphorus Pentoxide
110
Pyrogallol
65
Phosphorus Oxychloride
100
Phosphorus Pentachloride
100
S Salicylaldehyde
100
Phosphorus Trichloride
120
Salicylic Acid
120
Phthalic Acid
100
Salt Brine
150
Phthalic Anhydride
100
Sea Water
150
Picric Acid
50
Silicon Tetrachloride
120
Polyvinyl Acetate
150
Silver Chloride
150
Polyvinyl Alcohol
150
Silver Cyanide
150
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
350 Table 12.7. (Contd.) Chemical Silver Nitrate
Maximum Use Temperature, °C 150
Maximum Use Temperature, °C 150
Chemical Stannic Chloride
Sodium Acetate
150
Stannous Chloride
150
Sodium Benzene-Sulfonate
150
Stannous Fluoride
120
Sodium Benzoate
150
Stearic Acid
150
Sodium Bicarbonate
150
Stoddards Solvent
135
Sodium Bisulfate
150
Styrene Monomer
100
Sodium Bisulfite
150
Succinic Acid
135
Sodium Borate
100
Sulfamic Acid
100
Sodium Bromide
150
Sulfur (Molten)
120
Sodium Carbonate
150
Sulfur Dioxide
110
Sodium Chlorate
150
Sulfur Trioxide (Liquid)
25
Sodium Chloride
150
Sulfuric Acid (60%)
150
Sodium Chromate
150
Sulfuric Acid (Conc.)
150
Sodium Cyanide
150
Sulfuric Acid (FumingOleum)
50
Sodium Dichromate (Alkaline)
100
Sulfurous Acid
110
Sodium Ferricyanide
150
150
Sodium Ferrocyanide
150
T Tall Oil
Sodium Fluoride Sodium Glutamate
150 135
Tannic Acid Tartaric Acid
135 135
Sodium Hydroxide (10%)
110
2,3,4,6-Tetrachlorophenol
100
Sodium Hydroxide (50%)
110
Tetraethyl Lead
150
Sodium Hypochlorite
150
Tetrahydrofuran
100
Sodium Hyposulfite
150
Sodium Iodide
150
Tetramethyl Ammonium Hydroxide (50%)
100
Sodium Lignosulfonate
150
Sodium Metasilicate
150
Sodium Nitrate
150
Sodium Nitrite
150
Sodium Perborate
100
Sodium Perchlorate
65
Sodium Peroxide
150
Sodium Persulfate
80
Sodium Phosphate
150
Sodium Silicate
150
Sodium Silicofluoride
150
Sodium Sulfate
150
Sodium Sulfide
150
Sodium Sulfite
150
Sodium Thiosulfate
150
Sorbic Acid
135
Sour Crude Oil
150
Ch. 12: Chemical Properties of Fluoropolymers
Tin Tetrachloride
110
Toluene
120
Tributyl Phosphate
65
Trichloracetic Acid
100
Trichloroethylene
135
Trichloromethane
100
2,4,5-Trichlorophenol
100
Triethylamine
110
Trisodium Phosphate
135
Thionyl Chloride
100
Titanium Dioxide
150
Titanium Tetrachloride
100
Turpentine
135
U UDMH-Hydrazine (50/50)
50
Urea (50% H2O)
135
© Plastics Design Library
351 Table 12.7. (Contd.) Chemical
Maximum Use Temperature, °C
V Varsol
135
Vinyl Acetate
135
Vinyl Chloride (Monomer)
65
W Water
150
Water Sewage
135
Wax
150
X Xylene
120
Z Zinc Acetate
120
Zinc Chloride
150
Zinc Hydrosulfite (10%)
120
Zinc Nitrate
150
Zinc Sulfate
150
Zinc Sulfide
150
PLATING SOLUTIONS Brass
135
Cadmium
135
Chrome
135
Copper
135
Gold
135
Tests should be conducted in each specific application to verify the validity of the values provided. More specific data, based on aging experiments, have been listed in Table 12.8, which indicate the retained tensile properties and ETFE weight gain. Hydrolytic stability of ETFE is indicated by retention of its physical properties after extensive exposure to boiling water. Tensile strength and elongation changed little after 3,000 hours exposure of unfilled ETFE to boiling water (Table 12.9). PVDF, in general, resists inorganic acids, bases, salt solutions, oxidizing agents, and halogens. It is, however, attacked by concentrated sulfuric acid and medium concentration alkaline solutions. PVDF is
© Plastics Design Library
unaffected by alcohols, chlorinated solvents, aliphatic and aromatic hydrocarbons, and crude oil. It swells in some polar solvents such as ketones and esters. PVDF dissolves in some polar solvents like dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. Hot amines attack polyvinylidene fluoride. Table 12.10 indicates the maximum use temperature of PVDF for many chemicals. ECTFE is resistant to strong mineral and oxidizing acids, alkalis, metal etchants, liquid oxygen, and virtually all organic solvents with the exception of hot amines such as aniline and dimethyl amine. ECTFE is susceptible to attack by metallic sodium and potassium; the rate of attack is dependent on the time and temperature of exposure. Certain halogenated solvents can plasticize ECTFE without impairing its usefulness. After discontinuing contact between the part and the solvent, it dries and mechanical properties return to the original values. A conclusion of this observation is that the interaction between ECTFE and the solvents in these cases is strictly physical and not chemical. Table 12.11 gives the impact of a number of chemicals on ECTFE including tensile properties, weight gain, and color change. ECTFE is compatible with liquid oxygen (LOX) as measured by National Aeronautics and Space Administration (NASA) test method MSFCSPEC-106B. It is also resistant to nitrogen tetroxide (NTO) and monomethylhydrazine (MMH). Polyvinyl fluoride is resistant to most organic and inorganic chemicals. It is susceptible to strong oxidizing agents and alkaline metals such as sodium. In general, any chemical that affects fluoropolymers with higher fluorine content, such as PTFE, PFA, and ETFE, also attacks PVF. Table 12.12 provides swelling data for PVF immersed in a number of polar solvents.
12.4 Permeation Fundamentals Permeation can be defined as the passage of gases and liquids through a second material such as a solid. It is a significant consideration in the selection of plastic material for the construction of chemical processing equipment because process fluids may travel across the thickness of the polymer by permeation. Permeated species in sufficient quantities could cause corrosion, contamination, or unacceptable environmental emission, singly or in combination.
Ch. 12: Chemical Properties of Fluoropolymers
352 Table 12.8. Effect of Immersion in Various Chemicals on ETFE[7]
Retained Properties%
Boiling Point, °C
Test Temp., °C
Days
Tensile Strength
Elong.
Weight Gain
Acetic Acid (Glacial)
118
118
7
82
80
3.4
Acetic Anhydride
139
139
7
100
100
0
Trichloroacetic Acid
196
100
7
90
70
0
Trichloroacetic Acid
196
120
30
100
100
Mineral Oil
180
7
90
60
0
Naphtha
100
7
100
100
0.5
Benzene
80
80
7
100
100
0
Toluene
110
110
7
191
180
7
100
100
0
Aniline
185
120
7
81
99
2.7
Aniline
185
120
30
93
82
Aniline
185
180
7
95
90
N,N-Dimethylaniline
190
120
7
82
97
N-Methylaniline
195
120
7
85
95
N-Methylaniline
195
120
30
100
100
n-Butylamine
78
78
7
71
73
4.4
Di-n-Butylamine
159
120
7
81
96
Di-n-Butylamine
159
120
30
100
100
Di-n-Butylamine
159
160
7
55
75
Tri-n-Butylamine
216
120
7
81
80
Tri-n-Butylamine
216
120
30
100
100
Pyridine
116
116
7
100
100
1.5
Carbon Tetrachloride
78
78
7
90
80
4.5
Chloroform
62
61
7
85
100
4.0
Dichloroethylene
77
32
7
95
100
2.8
®
FREON 113
46
46
7
100
100
0.8
Methylene Chloride
40
40
7
85
85
0
Chemical Acid/Anhydrides
Aliphatic Hydrocarbons
Aromatic Hydrocarbons
Functional Aromatics O-Cresol Amines
Chlorinated Solvents
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
353 Table 12.8. (Contd.)
Retained Properties%
Boiling Point, °C
Test Temp., °C
Days
Tensile Strength
Elong.
Weight Gain
66
66
7
86
93
3.5
Acetone
56
56
7
80
83
4.1
Acetophenone
201
180
7
80
80
1.5
Cyclohexanone
156
156
7
90
85
0
Methyl Ethyl Ketone
80
80
7
100
100
0
n-Butyl Acetate
127
127
7
80
60
0
Ethyl Acetate
77
77
7
85
60
0
Dimethylformamide
154
90
7
100
100
1.5
Dimethylformamide
154
120
7
76
92
5.5
Dimethylsulfoxide
189
90
7
95
90
1.5
Benzoyl Chloride
197
120
7
94
95
Benzoyl Chloride
197
120
30
100
100
Benzyl Alcohol
205
120
7
97
90
Decalin
190
120
7
89
95
Phthaloyl
276
120
30
100
100
0
Aqua Regia
90
*
93
89
0.2
Chromic
125
125
7
66
25
Hydrobromic (Conc)
125
125
7
100
100
Hydrochloric (Conc)
106
23
7
100
90
0
Hydrochloric (Conc)
106
106
7
96
100
0.1
Hydrofluoric (Conc)
23
7
97
95
0.1
Nitric25%
100
100
14
100
100
Nitric50%
105
105
14
87
81
Nitric70% (Conc)
120
23
105
100
100
0.5
Nitric70% (Conc)
120
60
53
100
100
Nitric70% (Conc)
120
120
2
72
91
Nitric70% (Conc)
120
120
3
58
5
Nitric70% (Conc)
120
120
7
0
0
Chemical Ethers Tetrahydrofuran Aldehyde/Ketones
Esters
Polymer
Other Organics
Acids
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
354 Table 12.8. (Contd.)
Retained Properties%
Boiling Point, °C
Test Temp., °C
Days
Tensile Strength
Elong.
Weight Gain
Phosphoric (Conc)
100
7
Phosphoric (Conc)
120
7
94
93
0
Sulfuric (Conc)
100
7
100
100
0
Sulfuric (Conc)
120
7
98
95
0
Sulfuric (Conc)
150
*
98
90
0
Bromine (Anhy)
59
23
7
90
90
1.2
Bromine (Anhy)
59
57
7
99
100
Bromine (Anhy)
59
57
30
94
93
3.4
Chlorine (Anhy)
120
7
85
84
7
Ammonium Hydroxide
66
7
97
97
0
Potassium Hydroxide (20%)
100
7
100
100
0
Sodium Hydroxide (50%)
120
7
94
80
0.2
23
7
99
98
0
Ferric Chloride (25%)
104
100
7
95
95
0
Zinc Chloride (25%)
104
100
7
100
100
0
Sulfuryl Chloride
68
68
7
86
100
8
Phosphoric Trichloride
75
75
7
100
98
Phosphoric Oxychloride
104
104
7
100
100
Silicon Tetrachloride
60
60
7
100
100
Water
100
100
7
100
100
0
Skydrol
149
7
100
95
3.0
Aerosafe
149
7
92
93
3.9
A-20 Stripper Solution
140
7
90
90
Chemical
Halogens
Bases
Peroxides Hydrogen Peroxide (30%) Salt-Metal Etchants
Other Inorganics
Miscellaneous
*Exposed for 6 hours. NOTES: Change in properties of 15% is considered insignificant. Samples were 1015 mil microtensile bars. TS/E and wt. gain determined within 24 hours after removal from exposure media.
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
355 Table 12.9. Hydrolytic Stability of ETFE to Boiling Water[8] Length of Exposure, Hours
Resin Unfilled ETFE
Filled ETFE (containing 25% weight glass fiber)
Tensile Strength, MPa
Elongation, %
0
40
145
3,000
40
135
0
82
7
1,000
60
5
2,000
57.6
5
3,000
55.8
5
Table 12.10. Chemical Compatibility of Polyvinylidene Fluoride (PVDF)[9]
Chemical Substance
Concentration
Maximum Temp., °C
A
Chemical Substance
Concentration
Maximum Temp., °C
Aluminum Acetate
Aqueous solution or solid
135
Acetaldehyde
NR
Acetamide
25
Aluminum Bromide
Acetic Acid
50
Aluminum Chloride
Up to 40% in water
135
Aqueous solution or solid
135
Acetic Acid
10% in water
110
Acetic Acid
50% in water
95
Aluminum Fluoride
Acetic Acid
80% in water
80
Acetic Anhydride
NR
Aluminum Hydroxide
Acetone
NR
Aluminum Nitrate
Acetone
10% in water
50
135
135 Aqueous solution or solid
Aluminum Oxychloride
135 135
Acetonitrile
50
Acetophenone
NR
Acetyl Bromide
50
Acetyl Chloride
50
Ammonia, Gas
NR
Acetylacetone
NR
Ammonia, Liquid
NR
Acetylene
120
Acrylonitrile
25
Adipic Acid
65
Air
140
Aluminum Sulfate
Aqueous solution or solid
135
Ammonium Acetate
Aqueous solution or solid
80
Ammonium Alum
Aqueous solution or solid
135
95
Ammonium Bifluoride
Aqueous solution or solid
65
Allyl Alcohol
50
Ammonium Bromide
Aqueous solution or solid
120
Allyl Chloride
100
Ammonium Carbonate
Aqueous solution or solid
135
Alcoholic Spirits
© Plastics Design Library
40% Ethyl Alcohol
Ch. 12: Chemical Properties of Fluoropolymers
356 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Ammonium Chloride
Aqueous solution or solid
135
Barium Sulfate
135
Ammonium Dichromate
Aqueous solution or solid
Barium Sulfide
135
120
Beer
95
Ammonium Fluoride
Aqueous solution or solid
135
Beet Sugar Liquors
110
Benzaldehyde
20
Ammonium Hydroxide
Up to concentrated
110
Benzene
75
Ammonium Metaphosphate
Aqueous solution or solid
135
Ammonium Nitrate
Aqueous solution or solid
135
Ammonium Persulfate
Aqueous solution or solid
25
Ammonium Phosphate
Aqueous solution or solid
135
Ammonium Sulfate
Aqueous solution or solid
135
Ammonium Sulfide
Aqueous solution or solid
50
Ammonium Thiocyanate
Aqueous solution or solid
135
Amyl Acetate
50
Amyl Alcohol
135
Sec-Amyl Alcohol
50
Amyl Chloride
135
Aniline
50
Aniline Hydrochloride
Aqueous solution or solid
Aqua Regia Arsenic Acid
25 25
Aqueous solution
Asphalt
135 120
B Barium Carbonate Barium Chloride
135 Aqueous solution or solid
Barium Hydroxide Barium Nitrate
135 135
Aqueous solution or solid
135
Chemical Substance
Benzenesulfonic Acid
Aqueous solution or solid
Maximum Temp., °C
50
Benzoic Acid
110
Benzoyl Chloride
75
Benzoyl Peroxide
75
Benzyl Alcohol
120
Benzyl Chloride
135
Benzyl Ether
40
Benzylamine
Aqueous solution or liquid
25
Black Liquor
80
Bleaching Agents
135
Borax
135
Boric Acid
135
Boron Trifluoride
25
Brine
135
Brine, acid
135
Brine, basic
135
Brine, chlorinated acid
95
Bromic Acid
Aqueous solution
95
Bromine dry gas
65
Bromine, liquid
65
Bromine, Water
100
Bromobenzene
65
Bromoform
65
m-Bromotoluene
80
Butadiene
120
Butane
120
Butanediol
Ch. 12: Chemical Properties of Fluoropolymers
Concentration
Aqueous solution or
135
© Plastics Design Library
357 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Chemical Substance
Concentration
Maximum Temp., °C
25
Calcium Hydroxide
Aqueous solution or liquid
110
Calcium Hypochlorite
Aqueous solution or solid
95
Aqueous solution or solid
135
sec-Butyl Alcohol
Aqueous solution or liquid
Calcium Nitrate 95
t-Butyl Alcohol
Aqueous solution or liquid
95
Butyl Acetate Butyl Alcohol
135
Calcium Oxide
120
Calcium Phosphate
135
Calcium Sulfate
135
Cane Sugar Liquors
135
Butyl Acrylate
50
Caprylic Acid
80
Butyl Bromide
135
Carbon Dioxide
135
Butyl Chloride
135
Carbon Disulfide
25
Butyl Ether
40
Carbon Monoxide
135
Butyl Mercaptan
135
Carbon Tetrachloride
135
Butyl Stearate
40
Carbonic Acid
135
Casein
135
Castor Oil
135
Chloral Hydrate
25
Chlorinated Phenol
65
Butylamine
Aqueous solution or liquid
NR
sec-Butylamine
Aqueous solution or liquid
20
Aqueous solution or solid
20
t-Butylamine
5% in CCl4
Chlorine
95
Chlorine, gas
95
Chlorine, liquid
95
1-Butylene
135
Chlorine Dioxide
65
Butylphenol
110
Chlorine Water
110
Butyraldehyde
65
Butyric Acid
110
C
Chloroacetic Acid
Aqueous solution or pure
NR
Chloroacetyl Chloride
50 75
Calcium Acetate
Aqueous solution or solid
135
Chlorobenzene
Calcium Bisulfate
Aqueous solution or solid
135
Chlorobenzenesulfonic Acid
Calcium Bisulfite
Aqueous solution or solid
135
Chlorobenzyl Chloride
50
Calcium Bromide
Aqueous solution or solid
135
Chlorofluorocarbon 11
95
135
Chlorofluorocarbon 12
95
Chlorofluorocarbon 13
95
Calcium Carbonate Calcium Chlorate
Aqueous solution or solid
135
Calcium Chloride
Aqueous solution or solid
135
© Plastics Design Library
Aqueous solution or pure
95
Ch. 12: Chemical Properties of Fluoropolymers
358 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Chlorofluorocarbon 14
95
Chlorofluorocarbon 21
95
Chlorofluorocarbon 22
95
Chlorofluorocarbon 113
95
Chlorofluorocarbon 114
95
Chloroform
50
6-Chlorohexanol
75
Chlorohydrin
50
Chloropicrin
65
Chlorosulfonic Acid
NR
Chlorotrimethylsilane
50
Chrome Alum
Aqueous solution or solid
95
Chromic Acid
Up to 40% in water
80
Chromic Acid
50% in water
Chemical Substance
Concentration
Maximum Temp., °C
Corn Syrup
120
Cottonseed Oil
135
Cresol
65
Cresylic Acid
65
Crotonaldehyde
50
Crude Oil
135
Cryolite
120
Cuprous Chloride
120
Cyclohexane
135
Cyclohexanol
65
Cyclohexanone
25
Cyclohexyl Acetate
95
D Decane Dextrin
120 Aqueous solution or solid
120
Diacetone Alcohol
25
p-Dibromobenzene
95
1,2-Dibromopropane
95
50
Dibutyl Phthalate
NR
Chromyl Chloride
50
Dibutyl Sebacate
NR
Cider
60
Citric Acid
Aqueous solution or solid
135
Coal Gas
110
Coconut Oil
135
Copper Acetate
Aqueous solution or solid
Copper Carbonate, basic Copper Chloride
120 135
Aqueous solution or solid
135
Copper Cyanide
135
Copper Fluoride
135
Copper Nitrate Copper Sulfate
Aqueous solution or solid
135
Aqueous solution or solid
135
Corn Oil
Ch. 12: Chemical Properties of Fluoropolymers
Dibutylamine
Aqueous solution or liquid
20
Dichloroacetic Acid
Aqueous solution or liquid
50
o-Dichlorobenzene
65
Dichlorodimethylsilane
50
Dichloroethylene
110
2,2-Dichloropropionic Acid
50
==-Dichlorotoluene
65
Diesel Fuels
135
Diethanolamine
Aqueous solution or liquid
NR
135
© Plastics Design Library
359 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Aqueous solution or liquid
25
Chemical Substance
Concentration
Maximum Temp., °C
Ethyl Acetate
NR
Ethyl Acetoacetate
25
NR
Ethyl Acrylate
25
50
Ethyl Alcohol
Diglycolic Acid
25
Ethyl Chloride
135
Diisobutyl Ketone
95
Ethyl Chloroacetate
25
Diisobutylene
135
Ethyl Chloroformate
50
Diisopropyl Ketone
20
Ethyl Cyanoacetate
25
Dimethyl Acetamide
NR
Ethyl Ether
50
Dimethyl Formamide
NR
Ethyl Formate
25
Dimethyl Phthalate
25
Ethylbenzene
50
Dimethyl Sulfate
25
Diethylamine Diethyl Malonate Diethylenetriamine
Aqueous solution or liquid
Dimethyl Sulfoxide Dimethylamine
Aqueous soluton or gas
25
Ethylene Chlorohydrin
Ethylene Glycol
25
2,6Dimehyl-4heptanol
95
2,5-Dimethyl-1,5hexadiene
120
Dioctyl Phthalate
25
1,4,1,4-Dioxane
NR
2-Ethyl-1-hexanol
Dioxolane
NR
F
Dipropylene Glycol Methyl Ether
25
Disodium Phosphate Divinyl Benzene
95 50
E NR Aqueous solution or solid
Ethanethiol
80 25
Ethanolamine
Aqueous solution or liquid
NR
2-Ethoxyethyl Acetate
Aqueous solution or liquid
95
© Plastics Design Library
Aqueous solution or liquid
Ethylene Oxide Ethylenediamine
135
25 135 135 NR
Aqueous solution or liquid
110 120
Fatty Acids
135
Fatty Acids, Sulfonates
80
Ferric Chloride
Aqueous solution or solid
Ferric Hydroxide
Epichlorohydrin Epsom Salts
Aqueous solution or liquid
Ethylene Dichloride
Dimethylaniline
Aqueous solution or solid
Aqueous solution or liquid
Ferric Nitrate
135 120
Aqueous solution or solid
135
Ferric Sulfate
135
Ferric Sulfide
120
Ferrous Chloride
Aqueous solution or solid
Ferrous Hydroxide Ferrous Nitrate
135 120
Aqueous solution or solid
135
Ch. 12: Chemical Properties of Fluoropolymers
360 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Chemical Substance
Concentration
Maximum Temp., °C
Ferrous Sulfate
135
H
Fluorine
25
Heptane
135
135
Hexachloro-1,3butadiene
50
135
Fluoroboric Acid
Aqueous solution
Fluorosilic Acid Formaldehyde Formic Acid Fructose
37% in water
50
Hexamethylenediamine
NR/50
Aqueous solution or liquid
120
Hexamethylphosphotriamide
NR
Aqueous solution or solid
Hexane
135
135
Hexyl Alcohol
80
Fruit Juices, pulp
95
Fuel Oil
135
Fumaric Acid
65
Furan
NR
Furfural
25
Furfuryl Alcohol
Aqueous solution or liquid
Aqueous solution or liquid
95
Aqueous solution or solid
25
Aqueous solution or liquid
50
Aqueous solution
135
Hydrobromic Acid
Up to 50% in water
135
Hydrochloric Acid
Up to concentrated
135
Hydrocyanic Acid
Aqueous solution
135
Hydrofluoric Acid
Up to 40% in water
120
41100% in water
95
Hydrazine Hydrazine Dihydrochloride Hydrazine Hydrate
40
Hydriodic Acid
G Gallic Acid
25
Gas, manufactured
135
Gas, natural
135
Gasoline, leaded
135
Gasoline, sour
135
Gasoline, unleaded
135
Gelatin
120
Gin
95
Hydrofluoric Acid
135
Hydrogen
135
Glue
120
Hydrogen Chloride
135
Glutamic Acid
95
Hydrogen Cyanide
135
Hydrogen Fluoride
95
Glucose
Aqueous solution or solid
Glycerin
Aqueous solution or liquid
135
Glycine
Aqueous solution or solid
25
Glycolic Acid
25
Hydrogen Peroxide
Up to 30% in water
95
Hydrogen Peroxide
90% in water
20
Hydrogen Sulfide Hydrogen Sulfide
135 Aqueous solution
Hydroquinone Hypochlorous Acid
Ch. 12: Chemical Properties of Fluoropolymers
110 120
Aqueous
20
© Plastics Design Library
361 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
I Iodine
10% in Nonaqueous solvent
Chemical Substance Lithium Chloride
65 65
M
Iodoform
95
Isoamyl Ether
120
Magnesium Carbonate
Isobutyl Alcohol
120
Isooctane
120
Isophorone
80
Isopropyl Alcohol
60
Isopropyl Chloride
40
Isopropyl Ether
50
Isopropylbenzene
40
J Jet Fuel (JP4, JP5)
95
K Kerosene
135
L Lactic Acid
Aqueous solution or pure
50
Maximum Temp., °C
Aqueous solution or solid
120
Lubricating Oil
Iodine, gas
Aqueous solution or liquid
Concentration
Magnesium Chloride
135
135 Aqueous solution or solid
135
Magnesium Citrate
120
Magnesium Hydroxide
135
Magnesium Nitrate
Aqueous solution or solid
135
Magnesium Sulfate
Aqueous solution or solid
135
Maleic Acid
Aqueous solution or solid
120
Maleic Anhydride
25
Malic Acid
Aqueous solution or solid
120
Manganese Sulfate
Aqueous solution or solid
120
Mercuric Chloride
120
Mercuric Cyanide
120
Lanolin
120
Lard Oil
135
Lauric Acid
110
Mercury
135
Lauroyl Chloride
120
Methacrylic Acid
50
Lauryl Mercaptan
95
Methane
135
Lauryl Sulfate
120
Methanesulfonic Acid
Lead Acetate
Aqueous solution or solid
Lead Chloride Lead Nitrate
135 120
Aqueous solution or solid
120
Lemon Oil
120
Linoleic Acid
120
Linseed Oil
135
Lithium Bromide
© Plastics Design Library
110
Aqueous solution or solid
Aqueous solution or liquid
135
95
Methyl Acetate
40
Methyl Acrylate
40
120
Lead Sulfate
Aqueous solution or solid
Mercuric Nitrate
Methyl Alcohol
Aqueous solution or liquid
135
Methyl Bromide
135
Methyl Chloride
135
Methyl Chloroacetate
25
Methyl Chloromethyl Ether
25
Ch. 12: Chemical Properties of Fluoropolymers
362 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Chemical Substance
Concentration
Maximum Temp., °C
Methyl Ethyl Ketone
NR
Nitroethane
20
Methyl Isobutyl Ketone
NR
Nitrogen
135
Methyl Methacrylate
50
Nitrogen Dioxide
75
Methyl Salicylate
65
Nitroglycerin
50
Methylamine
NR
Nitromethane
50
Methylchloroform
50
Nitrotoluene
80
Methylene Bromide
80
Nitrous Oxide
NR
Methylene Chloride
NR
Methylene Iodine
95
Methylsufuric Acid
Aqueous solution or liquid
50
Methyltrichlorosilane
65
Milk
110
Mineral Oil
135
Motor Oil
135
Molasses
65
Morpholine
Aqueous solution or liquid
25
N Naphtha
135
Naphthalene
95
Nickel Acetate
Aqueous solution or solid
120
Nickel Chloride
Aqueous solution or solid
Nickel Nitrate Nickel Sulfate
O Octane
135
Octene
135
Oleic Acid
120
Oleum
NR
Olive Oil
120
Oxalic Acid
50
Oxygen
135
Ozone
110
P Palm Oil
95
Palmitic Acid
120
Paraffin
120
Paraffin Oil
120
Peanut Oil
120
Perchloric Acid
10% in water
95
Perchloric Acid
70% in water
50
Perchloroethylene
135
135
Perchloromethyl Mercaptan
50
Aqueous solution or solid
135
Petrolatum
135
Aqueous solution or solid
Petroleum
120
135
Phenol
80
Phenol
50
120
1-Phenol-2-sulfonic Acid
50
Phenyl Ether
50
Phenylhydrazine
50
Nicotine
20
Nicotinic Acid Nitric Acid
Up to 10% in water
50
Nitric Acid
11-50% in water
50
Nitric Acid
Concentrated
NR
Nitric Acid, fuming
NR
Nitrobenzene
25
Ch. 12: Chemical Properties of Fluoropolymers
5% in water
Phenylhydrazine Hydrochloride
Aqueous solution or solid
50
o-Phenylphenol
80
Phosgene
80
© Plastics Design Library
363 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
Phosphoric Acid
Less than 85% in water
135
Phosphoric Acid
85% in water
110
Chemical Substance Potassium Acetate Potassium Alum
Concentration
Maximum Temp., °C
Aqueous solution or solid
135
Aqueous solution or liquid
135
Phosphorus, red
25
Phosphorus, Oxychloride
NR
Potassium Aluminum Chloride
Phosphorus, Pentachloride
95
Potassium Bicarbonate
Aqueous solution or solid
95
Phosphorus, Pentoxide
95
Potassium Bisulfate
Aqueous solution or solid
135
Phosphorus, Trichloride
95
Potassium Borate
Aqueous solution or solid
135
Phthalic Acid
95
Picric Acid
25
Potassium Bromate
Aqueous solution or solid
135
Potassium Bromide
Aqueous solution or solid
135
Potassium Carbonate
Aqueous solution or solid
135
Plating Solutions: Brass Plating Solutions: Cadmium Plating Solutions: Chrome Plating Solutions: Copper Plating Solutions: Iron Plating Solutions: Lead Plating Solutions: Nickel Plating Solutions: Rodium Plating Solutions: Silver Plating Solutions: Speculum Plating Solutions: Tin Plating Solutions: Zinc
95 95 95
95 95 95 95
95
Potassium Chloride
Aqueous solution or solid
135
Potassium Chromate
Aqueous solution or solid
135
Potassium Cyanide
Aqueous solution or solid
135
95 Potassium Dichromate
135
Potassium Ferricyanide
Aqueous solution or solid
135
Potassium Ferrocyanide
Aqueous solution or solid
135
Potassium Fluoride
Aqueous solution or solid
135
95
Potassium Hydroxide
Up to 10% in water
85
95
Potassium Hydroxide
Greater than 50% in water
NR
Aqueous solution
95
Potassium Iodide
Aqueous solution or solid
120
Potassium Nitrate
Aqueous solution or solid
135
Polyethylene Glycol
95
Polyvinyl Acetate
135
Polyvinyl Alcohol
135
Potassium
NR
© Plastics Design Library
Potassium Chlorate
95
95
135
Potassium Hypochlorite
Ch. 12: Chemical Properties of Fluoropolymers
364 Table 12.10. (Contd.)
Maximum Temp., °C
Chemical Substance
Concentration
Maximum Temp., °C
Sodium Benzoate
Aqueous solution or solid
135
Sodium Bicarbonate
Aqueous solution or solid
135
Sodium Bisulfate
Aqueous solution or solid
135
135
Sodium Bisulfite
Aqueous solution or solid
135
Potassium Sulfide
135
Propane
135
Sodium Bromate
Aqueous solution or solid
95
Propyl Acetate
40
Sodium Bromide
Aqueous solution or solid
135
65
Sodium Carbonate
Aqueous solution or solid
135
Propylamine
NR
Sodium Chlorate
120
Propylene Dibromide
Aqueous solution or solid
95
Sodium Chlorite
120
Propylene Dichloride
95
Aqueous solution or solid
Sodium Chromate
Aqueous solution or solid
95
Sodium Cyanide
Aqueous solution or solid
135
Chemical Substance
Concentration
Potassium Perborate
135
Potassium Perchlorate
95
Potassium Permanganate
Aqueous solution or solid
Potassium Persulfate Potassium Sulfate
Propyl Alcohol
Propylene Glycol
120 50
Aqueous solution or solid
Aqueous solution or liquid
Aqueous solution or liquid
65
Propylene Oxide
NR
Pyridine
NR
Sodium Dichromate
Aqueous solution or solid
95
50
Sodium Dithionite
Aqueous solution or solid
40
Salicylaldehyde
50
Sodium Ferricyanide
Aqueous solution or solid
135
Salicylic Acid
95
Sodium Ferrocyanide
Aqueous solution or solid
135
Sodium Fluoride
Aqueous solution or solid
135
Pyrogallol
Aqueous solution or solid
S
Selenic Acid
Aqueous solution or pure
65
Silicon Tetrachloride
50
Silicone Oil
120
Sodium Fluosilcate
Silver Cyanide
135
Sodium Hydrogen Phosphate
Aqueous solution or solid
120
Sodium Hydroxide
Up to 10% in water
85
Sodium Hydroxide
Greater than 50% in water
NR
Sodium Hypochlorite
Up to 5% in water
135
Sodium Hypochlorite
615% in water
95
Silver Nitrate
Aqueous solution or solid
135
Silver Sulfate
120
Sodium
NR
Sodium Acetate
Aqueous solution or solid
Sodium Amalgam
Ch. 12: Chemical Properties of Fluoropolymers
135 NR
95
© Plastics Design Library
365 Table 12.10. (Contd.)
Concentration
Maximum Temp., °C
Sodium Iodide
Aqueous solution or solid
135
Sodium Nitrate
Aqueous solution or solid
135
Sodium Nitrite
Aqueous solution or solid
Chemical Substance
Sodium Palmitate Sodium Perchlorate
Aqueous solution or solid
Sodium Peroxide
Chemical Substance
Concentration
Maximum Temp., °C
T Tall Oil
135
Tallow
135
Tannic Acid
110
135
Tar
120
120
Tartaric Acid
120
1,1,2,2-Tetrabromoethane
120
1,1,2,2-Tetrachloroethane
120
2,3,4,6-Tetrachlorophenol
65
Tetraethyllead
135
95
Sodium Phosphate
Aqueous solution or solid
135
Sodium Thiocyanate
Aqueous solution or solid
120
Sodium Thiosulfate
Aqueous solution or solid
135
Sour Crude Oil
135
Soybean Oil
120
Stannic Chloride
Aqueous solution or liquid
135
Stannous Chloride
Aqueous solution or solid
135
Tetrahydrofuran Tetramethylammonium Hydroxide
Aqueous solution or solid
120
Aqueous solution or liquid
NR
Up to 10% in water
95
Tetramethylurea
NR
Thioglycol
25
Thioglycolic Acid
80
Starch
95
Thionyl Chloride
NR
Stearic Acid
135
Stilbene
80
Thiophosphoryl Chloride
NR
Styrene
85
Thread Cutting Oils
95
Succinic Acid
65
65
Sugar Syrup
135
Titanium Tetrachloride
Sulfur
120
Toluene
80
Sulfur Chloride
25
Toluenesulfonyl Chloride
50
Sulfur Dichloride
25
Tomato Juice
95
Sulfur Dioxide
80
Tributyl Phosphate
25
Sulfur Trioxide
NR
Sulfuric Acid Sulfuric Acid Sulfuric Acid Sulfuric Acid, fuming Sulfuryl Chloride Sulfuryl Fluoride
© Plastics Design Library
Up to 60% in water
120
8093% in water 98% in water
95 65 NR NR 25
Trichloroacetic Acid
Up to 10% in water
95
Trichloroacetic Acid
50% in water to pure
50
1,2,4-Trichlorobenzene
95
1,1,2-Trichloroethane
65
Trichloroethylene
135
Ch. 12: Chemical Properties of Fluoropolymers
366 Table 12.10. (Contd.) Chemical Substance
Concentration
Maximum Temp., °C
2,4,5Trichlorophenol
65
Tricresyl Phosphate
NR
Triethanolamine
Aqueous solution or liquid
50
Triethyl Phosphate
NR
Triethylamine
50
Trifluoroacetic Acid
50% in water
Trifluoroacetic Acid Trimethylamine
95 50
Aqueous solution or gas
Turpentine
65 135
U Urea
Aqueous solution or solid
120
V Varnish
120
Varsol
120
Vegetable Oil
135
Vinegar
110
Vinyl Acetate
120
Ch. 12: Chemical Properties of Fluoropolymers
Chemical Substance
Concentration
Maximum Temp., °C
Vinyl Chloride
95
Vinylidene Chloride
95
W Water
135
Water, salt
135
Water, sewage
120
Whiskey
95
Wine
95
X Xylene
95
Z Zinc Acetate
Aqueous solution or solid
120
Zinc Bromide
Aqueous solution or solid
120
Zinc Chloride
Aqueous solution or solid
135
Zinc Nitrate
Aqueous solution or solid
135
Zinc Sulfate
Aqueous solution or solid
135
© Plastics Design Library
367 Table 12.11. Chemical Compatibility of Ethylene-Chlorotrifluoroethylene Copolymer[10] Retained Properties Test Temp., °C
Tensile Strength
Elongation
Weight Gain, %
Color Change
Acetic Acid
140
I
I
3.4
1
Ammonium Hydroxide, 30%
140
I
I
1.2
2
Butanol n
121
I
I
1.9
1
Chromic Acid, 30%
100
I
I
0.0
2
Hydrochloric Acid, 37%
100
I
I
0.7
3
Hydrofluoric Acid, 49%
100
I
I
0.2
2
Hydrogen Peroxide (60%)
30
I
I
0.3
1
Methanol
50
I
I
0.4
1
n-Methylpyrrolidone
20
I
I
1.5
1
Methylene Chloride
50
I
I
4.1
1
Nitric Acid, 10%
121
I
I
0.4
1
Nitric Acid, 90%
71
I
I
2.3
2
Phosphoric Acid, 85%
140
I
I
-0.1
2
Potassium Hydroxide, 50%
121
I
I
-0.1
2
Propanol *
50
I
I
0.16
1
Sodium Hydroxide, 50%
132
I
I
-0.2
2
Sodium Hypochlorite, 5%
121
I
I
0.1
1
Sulfuric Acid, 98%
121
I
I
0.7
3
Toluene
20
I
I
0.7
1
Chemical Name
* tested for 28 days; all others tested at 30 days. Values are comparable. LEGEND RETAINED PROPERTIES:
COLOR CHANGE:
I Insignificant
1- no change 2- any shade of tan 3- brown or black
Table 12.12. Room Temperature Swelling of PVF in Organic Solvents[11]
Solvent
Swelling, wt%
Ethanol
4.8
Acetone
7.0
Dimethyl Formamide
32.3
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
368 In its simplest form, permeation can be expressed as a product of the solubility and diffusion coefficient of the permeant in the polymer. Permeation of a gas can be calculated from Eq. 12.1. This equation is derived from Ficks first law of mass transfer. Permeation concerns the movement of a species through the molecules of another species, e.g., a gas through a polymer. It does not take into account transport of material through cracks, voids, and in general physical flaws in the structure of the second species such as the polymer. To be sure, both phenomenon result in the migration of chemicals through the structure. This means that after an appropriate plastic material has been selected to meet the permeation requirements of a process, the equipment must be fabricated carefully to avoid flaws in the polymer structure. Eq. (12.1)
P=D·S
P (cm3/sec·cm·atm) is the permeability of the gas, D is the diffusion coefficient (cm3/sec), and S (cm3/cm3·atm) is the solubility coefficient. Several factors affect the permeation rate of the polymer. Temperature increase raises the permeation rate for two reasons. First, solubility of the permeant increases in the polymer at higher temperatures. Second, polymer chain movements are more abundant which allow easier diffusion of the permeant. The permeation rate of gases increases at higher partial pressures. For liquids, permeation rates rise with an increase in the concentration of the permeant. Unless the permeant species are highly soluble in the polymer, the permeation rate increases linearly with pressure, concentration, and the area of permeation. The permeation rate decreases at higher thickness, as illustrated in Fig. 12.3 for water transmission through a perfluorinated ethylene propylene copolymer (FEP). The effect of thickness is usually nonlinear. The permeation rate is very high at a low thickness and rapidly decreases with an increase in the thickness. After a critical thickness is reached, the effect of thickness is diminished and the permeation rate reaches a plateau. At lower thicknesses, the effect of surface structure begins to play a significant role in the permeation. A more oriented (ordered) surface will serve to inhibit permeation. Chemical and physical characteristics of the polymer have powerful effects on the rate of permeation, as much as four orders of magnitude.[12] Chemical affinity for the permeant, intermolecular forces such as van der Waals and hydrogen bonding forces, degree of
Ch. 12: Chemical Properties of Fluoropolymers
crystallinity, and degree of cross-linking are the influential variables. A similarity of chemical functional structures of the polymer and the permeant will promote solubility and permeation rate. Higher intermolecular forces of the polymer result in less permeation because of the resistance that they present to the development of space between adjacent molecules required for the passage of the permeant. Crystallinity is an important factor, which can be controlled during the processing of the polymer. The crystalline phase can be considered impermeable by most species because of its orderly structure (packing) which usually minimizes its specific volume. This means that there is little or no free space among the polymer chains for the passage of a permeant. The amorphous phase has the opposite construction and is disorderly with interchain space available for permeation. The specific volumes of the crystalline (0.43 cm3/g) and amorphous (0.5 cm3/g) phases of PTFE provide evidence for the argument. The amorphous phase has a 13% higher specific volume, which translates into additional space for permeation. Finally, cross-linking acts somewhat similar to crystallinity, though less effective, to limit space for permeation. Cross-linking is size-dependent and smaller species may permeate.
Figure 12.3 Water vapor transmission rate of Teflon® FEP resins at 40°C.[13]
© Plastics Design Library
369 The molecular size of the permeant, its chemical structure, and its condensation characteristics affect permeation. Diffusion of the permeant increases as its molecular size decreases, thus contributing to an increase in permeation. Molecular structure is important. A polar chemical will normally have a lower permeation rate in a nonpolar polymer than a nonpolar species and vice versa. This is due to the ability of chemicals with similar structures to the polymer to swell the polymer, that is, to create space between the chains for permeation. A more easily condensed chemical will also be more effective in swelling the polymer, resulting in higher rates of permeation.
12.5 Permeation Measurement and Data A number of methods can be used to measure permeation rate through polymers including fluoropolymers. These methods are helpful for comparison of different materials. The extent of the information obtained is limited due to the inability of these techniques
to account for real-world conditions. Typically, a film of fluoropolymer acts as a barrier to keep a gas or liquid in a reservoir. Figure 12.4 shows the schematic of a Thwing Albert cup for measuring liquid and vapor permeation. Permeation rate is calculated from the measured pressure or weight loss in the reservoir. Examples of techniques include ASTM Methods D 813 and F-739-81. There are more complex means of measuring permeation which approach the actual applications conditions. One example is a controlled recirculation of a fluid through a closed loop system which contains commercially manufactured parts made with the fluoropolymers, such as lined components. In these systems, gas chromatography and mass spectroscopy are used to analyze the permeation. A comparison of moisture vapor permeation through various polymers can be seen in Table 12.13. Notice that PCTFE is only second to FEP and both are among the most resistant plastics to water vapor permeation. Permeation data for gases and liquids through fluoroplastics are presented in Figs. 12.5 and 12.6. Permeability data can be found in Appendices IIV.
Figure 12.4 Schematics of a Thwing Albert cup for measuring liquid and vapor permeation.
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers
370 Table 12.13. Permeation (Transmission) of Water and Gases through Polymer Films[15]
Water Vapor Transmission 2
Polymer Film
1
ACLAR® UltRx, SupRx, Rx
gm-mil 100 in /24 hrs @ 100°F @ 90% RH
cc (STP) mil/100 in2/24 hr-ATM @ 77°F
(gm-mm/m2/24 hrs @ 37.8°C @ 90% RH)
(cc [STP]-mm/m2/24 hr-ATM @ 25°C)
O2
N2
CO2
0.016
7
1
14
(0.006)
(2.8)
(0.4)
(5.5)
0.020
7
1
16
(0.008)
(2.8)
(0.4)
(6.3)
0.026
15
2.5
40
(0.010)
(5.9)
(1.0)
(15.7)
0.027
12
2.5
30
(0.011)
(4.7)
(1.0)
(12.0)
0.200.6
0.86.9
0.121.5
3844
(0.080.24)
(0.32.7)
(0.050.6)
(1517)
1.01.5
500
180
2700
(0.390.59)
(195)
(71)
(1060)
0.7
250535
85315
1002500
(0.28)
(100210)
(35125)
(40985)
0.3
185
42
580
(0.12)
(73)
(17)
(230)
1920
2.6
0.9
4.7
(7.57.9)
(1.0)
(0.35)
(1.9)
0.22
715
320
1670
(0.008)
(281)
(125)
(660)
2.1
7.5
0.25
11
(0.81)
(3)
(0.10)
(4.3)
2.5
3.4
9
5.5
(1.0)
(1.34)
(3.5)
(2.2)
1.01.3
3.06.0
0.71.0
1525
(0.390.51)
(1.22.4)
(0.280.39)
(5.99.8)
ACLAR® 33C ®
ACLAR 22C ®
ACLAR 22A
PVC, PVDC Copolymer
Gas Transmission
Polyethylene Low Density Medium Density High Density CAPRAN® 77C (Nylon 6) Fluorinated Ethylene Propylene Polyvinyl Fluoride Polyvinylidine Fluoride
PolyesterPET Oriented 1ACLAR®
is made from polychlorotrifluoroethylene.
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
371
Figure 12.5 Effect of density of Teflon® FEP resins on their permeability to gases at 30°C.[13]
Figure 12.6 Permeability through PTFE and ETFE.[16]
12.6 Environmental Stress Cracking A weakness of many polymers is their tendency to fail at fairly low stress levels due to the impact of some hostile environments. This phenomenon is known as environmental stress cracking. Cracking occurs when the polymer is stressed for a long time under loads that are relatively small compared to the yield point of the material. A well-known example includes the failure of vulcanized natural rubber in the presence of ozone. It reacts with unsaturated hydrocarbons at the surface and, even when the elastomers are subjected to low stresses, cracks can
© Plastics Design Library
develop and lead to failure. Another example is stress cracking of polyolefins such as high-density polyethylene in the presence of surfactants. When polyethylene is held under stress in the presence of some detergents, its behavior changes from short time ductile failure at high stresses to brittle fracture at low stresses after relatively longer times with very small break elongations.[17] Even though environmental stress cracking must be considered in designing parts from fluoropolymers, it is not considered an extensive problem for this family of plastics. Permeation variables have a strong influence on stress cracking. Different fluoropolymers
Ch. 12: Chemical Properties of Fluoropolymers
372 differ in their propensity to environmental stress cracking, primarily based on their degree of crystallinity. Crystallinity can be lowered by adding a comonomer and varying its concentration. A higher comonomer content decreases the crystalline phase content of the polymer. Resin processing can affect crystallinity. Fast cooling (or quenching) at the end of the fabrication process serves to reduce crystalline content and increase amorphous content. Lowering the crystalline phase content of the part tends to increase resistance to stress cracking due to the increasing break elongation. Increasing the molecular weight of the polymer reduces its crystallinity and enhances its stress crack resistance. Longer chains have higher tensile strength, i.e., load-bearing ability. Chemicals with structures similar to the polymer tend to permeate and plasticize, thus, reducing its mechanical strength. Fluoropolymers can be permeated by small halogenated molecules, usually con-
taining chlorine and fluorine due to their similarity of structures. Environmental stress cracking effect of chemicals on polymers can be measured by exposing the polymer to the chemical under the desired conditions. Tensile properties of the exposed sample can then be measured. Any loss of elongation and tensile strength would indicate environmental stress cracking. Processing of the fluoropolymers plays an important role in minimizing the tendency to undergo stress crack resistance. Reducing crystallinity as much as possible and minimizing residual stresses lowers the tendency of a part to experience environmental stress cracking. These objectives can be achieved by reducing processing times and cool-down rates, and annealing. Another issue is the stress that a part experiences in application. Tensile loads cause less tendency for stress cracking than compressive loads. Fluoropolymer-lined equipment and parts are examples of objects which may contain residual stresses due to their design and/or fabrication.
References 1. High Performance Fluorpolymer Coatings & Linings, Ausimont Montedison Group, www.ausiusa.com, Pub. AWD-5, Nov. 1998. 2. Teflon® PTFE Fluoropolymer Resin, Properties Handbook, DuPont Co., Jul. 1996. 3. Teflon® Fluorocarbon Resin, Performance Guide for the Chemical Processing Industry, DuPont, Technical Bulletin No. E-21623-3. 4. Teflon® PFA Fluoropolymer Resin, Properties Handbook, DuPont Co., May 1997. 5. Vita, G., and Pozzoli, M., MFA: Technical Paper, A New Perfluoropolymer for Molding, Extrusion and Coating Applications, Ausimont S. p. A., Italy. 6. Exploring the Chemical Resistance of Teflon® Resins, The Journal of Teflon®, 3 No. 9, Nov./Dec. 1962. 7. TEFZEL® Fluoropolymer, Chemical Use Temperature Guide, DuPont Co., Apr. 1990. 8. TEFZEL® ETFE Fluoropolymer Resin, Properties Handbook, No. E-31301-5, DuPont Co., Jul. 1996. 9. KYNAR® Polyvinylidene Fluoride, Chemical Resistant Chart, Elf Atochem Corporation, Philadelphia, PA. 10. HALAR® ECTFE Fluoropolymer, Design Guide ECTFE, Ausimont Montedison Group, Thorofare, NJ, Jun. 1997. 11. Brasure, D. E., and Ebnesajjad, S., Vinyl Fluoride Polymers, in: Encyclopedia of Polymer Science and Engineering, 2nd ed., 17:468491, John Wiley & Sons, New York, 1989. 12. Imbalzano, J. F., Washburn, D. N., and Mehta, P. M., Basics of Permeation and Environmental Stress Cracking in Relation to Fluoropolymers, Technical Information, DuPont Co., No. H-24240-1, Nov. 1993.
Ch. 12: Chemical Properties of Fluoropolymers
© Plastics Design Library
373 13. Teflon® FEP Fluoropolymer Resin, Properties Handbook, DuPont Co., publication No. H-37052-3, Jan. 1998. 14. Fuel Alcohol Permeation Rates of Fluoropolymers, Fluoroplastics, and Other Fuel Resistant Materials, W. M. Stahl and R. D. Stevens, DuPont Co., SAE Technical Paper Series 920163, presented at Int. Cong. & Exp., Detroit, MI, February 2428, 1992, reprinted in Teflon®/Tefzel® Technical Information, publication No. H-38086, June 1992. 15. ACLAR® Barrier Films, Technical Bulletin SFI-14, Allied Signal Advanced Materials, Morristown, NJ. 16. Teflon® Fluorocarbon Resins in Chemical Service, J. Teflon®, Publ. by DuPont Co., Jan.Feb. 1970. 17. Young, R. J., and Lovell, P. A., Introduction to Polymers, 2nd ed., Chapman & Hall, London, 1991.
© Plastics Design Library
Ch. 12: Chemical Properties of Fluoropolymers