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Investigation of registration properties of some fluoropolymers
R_,~_'_~,~onMeaJurements, Voi. 25, Noe 1.4, pp. 181-182, 1995 Copyright © 1995 Elsevier Science Ltd Primed in Great Britain. All rigl~ reserved i 350-4487/95 $9.50 + .00
13.~ ~S7(95)00069-0
INVESTIGATION OF REGISTRATION PROPERTIES OF SOME FLUOROPOLYMERS
V. V. SHIRKOVAand S. P. TRETYAKOVA Joint Institute for Nuclear Research, Flerov Laboratory of Nuclear Reactions, 141980 Dubna, Russia
ABSTRACT Investigation of heavy ion radiolysis of polyvinylidenfluoride and its copolymers has shown that registration properties of materials depend on quantity of hydrogenous fragments in the polymer chain which produce lightly oxidizing double bonds in the chain under irradiation. Therefore, polyvinylidenfluoride has the lowest registration threshold. The mechanical properties of copolymers are better than those of PVDF. Moreover, the copolymers have significantly higher etching selectivity that improves pore shape in track membranes. KEYWORDS Fluoropolymers,
irradiation,
tracks,
chemical etching, heavy ions.
INTRODUCTION Among polymers which are used for obtaining track membranes the class of fluoropolymers is characterized by its chemical resistance. Up to now polyvinylidenfluoride (PVDF) track membranes with high chemical resistance and high absorption ability, in particular, to biological objects are obtained. It is known that vinylidenfluoride (VDF) is copolymerized easily with other fluoropolymers. In this case the properties of obtained polymer materials are changed. It means that there is a possibility to obtain track membranes with various mechanical and chemical properties from the hard up to the very high-elastic ones with conserving high chemical resistance [I]. For such copolymers the processes of radiolysis have not been studied. EXPERIMENTAL AND RESULTS In the present work the materials of domestic manufacture in the form of biaxially oriented films from I0 to SO Hm in thickness and pressed plates I-2 mm in thickness have been used: PVDF, F-2, (CH -CF ) p=1,75 g/cm 3 and its copolymers with TFE (~5% of 2
zn
[(CHz-CFz)m (CFz-CFz-)p ]n' p=1,77 g/cm a, ItFP (~10% of w e i g h t ) - F - 2 6 [(-CH2-CF2-)m(-CFz-CF-) p ]n' P=1'79 g/cma'
weight)-F-ZM,
TFCE (~ION of weight) F-23,
[(-CH2-CF2-)m!-CF2CFCI-)p ]n' P=1'74 g/cm3"
C r y s t a i i i n i t y of ai1 samples i s near 50g. The c o n d i t i o n s of i r r a d i a t i o n u s i n g
the U-300 and
accelerators are presented in Table I. The products identified with the help of UV- and IR-spectroscopy and "Specord M-80" spectrophotometers. The polymers in alkali (13% NaOH) saturated solution KMnO [2].
IC-IO0 FLNR J I l ~
of radiolysis have been using the "Specord M-40" have been etched at 95°C The parameters of etched
4
tracks have been measured using the optical microscopy. The ranges and REL in studied materials have been calculated with the program [3]. The quantity of gel-fraction has been determined after dissolving the films irradiated by ions in dimethylformamide.
182
V.V. S H I R K O V A a n d S.P. T R E T Y A K O V A
Table I. The values REL ~=1000 eV [3], fluences and energy of different and range values. Ions
Energy ME/amu
REL MeV/cmZ-mg
Fluence(N) i/c~
ions
Ion range, pm Rcal. IRoxp.
160
I, 0
8, 0
106
10, 4
10, 0+0, 7
22Ne
2, 0
8, 3
106-1014
20, 4
20, 0-+I,0
4°At
5, 6
12, 0
106-1012
55, 0
53, 0-+2,0
132Xe
I, 0
58, 3
106-1011
17, 0
19, 0-+1,0
In order to demonstrate the role of "hydrogen defects" in the polymer chain and the dependence of registration properties of polymer-type the UVand IR-spectra irradiated by different ions and different fluences of copolymer ions have been analyzed. The most pronounced changes of the IRspectra of copolymers under heavy ion irradiation are seen in the frequency range of 1600-1800 cm-1 typical for stretching vibrations of double bonds. The formation of two intensive bands at 1713 and 1754 cm -I after irradiation -I was typical for all co polymers investigated. The band 1754 cm strongly suggests to be referred to stretching vibrations of the link double bond (CF-CH=CF ), and the band 1713 cm -I - to stretching vibrations 2
(-CF=CH-CF -) 2
[4,]. Moreover, one can see the saturation below the band 1713 cm-* up to -i . 1600 cm in the form of a wide arm, which can be assigned to a different set of conjugated double bonds. The formation of double bonds at heavy ion radiolysis is explained by HF separation. The optical density changes for different types of polymers under the same conditions of irradiation (film thickness is 20 ~m, 4CAr, N=5.10 n ion/cmZ). F-2 has the maximum value of optical density at A=335 nm. One can conclude that the greater is the hydrogenous fragments (-CH -CF -) in the polymer chain the higher will be the 2
2
radiation yield of double bonds . The increase of absorption over all UV- and visible spectra indicates a great variety of conjugation (two, three or more double bonds with different types of replacement) having an accidental character. Since the etching track rate is connected with the quantity and type of radiolysis products in the given case of all with the quantity of double bonds which are oxidated by etching solution. One can assume that the maximum etching track rate and maximum sensitivity should be observed for the pure PVDF (F-2) that fully corresponds to experimental data. REFERENCES
I. Panshin Yu.A.,Malkevitch S.G.,Dunaevskaya C.S. (1978).Fluoroplastics, "Chemistry", Leningrad. 2. Tretyakova S.P., Shirkova V.V. (1986) Polyvinylidenefluorlde as Charged Particle Detector. Nuclear Tracks, v. 12, N I-6, pp. 75-76, 3. Almasi Gy., Somogyi G. (1981] Range and REL data for light and heavy ions in CR-39, CN-85 and PC nuclear track detectors, ATOMKI Koezlemenyek, N 23, p.99-I12. 4. Socrates G. (1980). Infrared Characteristic Group Frequencies, John Wiley and Sons, New-York.
13.~ ~S7(95)00069-0
INVESTIGATION OF REGISTRATION PROPERTIES OF SOME FLUOROPOLYMERS
V. V. SHIRKOVAand S. P. TRETYAKOVA Joint Institute for Nuclear Research, Flerov Laboratory of Nuclear Reactions, 141980 Dubna, Russia
ABSTRACT Investigation of heavy ion radiolysis of polyvinylidenfluoride and its copolymers has shown that registration properties of materials depend on quantity of hydrogenous fragments in the polymer chain which produce lightly oxidizing double bonds in the chain under irradiation. Therefore, polyvinylidenfluoride has the lowest registration threshold. The mechanical properties of copolymers are better than those of PVDF. Moreover, the copolymers have significantly higher etching selectivity that improves pore shape in track membranes. KEYWORDS Fluoropolymers,
irradiation,
tracks,
chemical etching, heavy ions.
INTRODUCTION Among polymers which are used for obtaining track membranes the class of fluoropolymers is characterized by its chemical resistance. Up to now polyvinylidenfluoride (PVDF) track membranes with high chemical resistance and high absorption ability, in particular, to biological objects are obtained. It is known that vinylidenfluoride (VDF) is copolymerized easily with other fluoropolymers. In this case the properties of obtained polymer materials are changed. It means that there is a possibility to obtain track membranes with various mechanical and chemical properties from the hard up to the very high-elastic ones with conserving high chemical resistance [I]. For such copolymers the processes of radiolysis have not been studied. EXPERIMENTAL AND RESULTS In the present work the materials of domestic manufacture in the form of biaxially oriented films from I0 to SO Hm in thickness and pressed plates I-2 mm in thickness have been used: PVDF, F-2, (CH -CF ) p=1,75 g/cm 3 and its copolymers with TFE (~5% of 2
zn
[(CHz-CFz)m (CFz-CFz-)p ]n' p=1,77 g/cm a, ItFP (~10% of w e i g h t ) - F - 2 6 [(-CH2-CF2-)m(-CFz-CF-) p ]n' P=1'79 g/cma'
weight)-F-ZM,
TFCE (~ION of weight) F-23,
[(-CH2-CF2-)m!-CF2CFCI-)p ]n' P=1'74 g/cm3"
C r y s t a i i i n i t y of ai1 samples i s near 50g. The c o n d i t i o n s of i r r a d i a t i o n u s i n g
the U-300 and
accelerators are presented in Table I. The products identified with the help of UV- and IR-spectroscopy and "Specord M-80" spectrophotometers. The polymers in alkali (13% NaOH) saturated solution KMnO [2].
IC-IO0 FLNR J I l ~
of radiolysis have been using the "Specord M-40" have been etched at 95°C The parameters of etched
4
tracks have been measured using the optical microscopy. The ranges and REL in studied materials have been calculated with the program [3]. The quantity of gel-fraction has been determined after dissolving the films irradiated by ions in dimethylformamide.
182
V.V. S H I R K O V A a n d S.P. T R E T Y A K O V A
Table I. The values REL ~=1000 eV [3], fluences and energy of different and range values. Ions
Energy ME/amu
REL MeV/cmZ-mg
Fluence(N) i/c~
ions
Ion range, pm Rcal. IRoxp.
160
I, 0
8, 0
106
10, 4
10, 0+0, 7
22Ne
2, 0
8, 3
106-1014
20, 4
20, 0-+I,0
4°At
5, 6
12, 0
106-1012
55, 0
53, 0-+2,0
132Xe
I, 0
58, 3
106-1011
17, 0
19, 0-+1,0
In order to demonstrate the role of "hydrogen defects" in the polymer chain and the dependence of registration properties of polymer-type the UVand IR-spectra irradiated by different ions and different fluences of copolymer ions have been analyzed. The most pronounced changes of the IRspectra of copolymers under heavy ion irradiation are seen in the frequency range of 1600-1800 cm-1 typical for stretching vibrations of double bonds. The formation of two intensive bands at 1713 and 1754 cm -I after irradiation -I was typical for all co polymers investigated. The band 1754 cm strongly suggests to be referred to stretching vibrations of the link double bond (CF-CH=CF ), and the band 1713 cm -I - to stretching vibrations 2
(-CF=CH-CF -) 2
[4,]. Moreover, one can see the saturation below the band 1713 cm-* up to -i . 1600 cm in the form of a wide arm, which can be assigned to a different set of conjugated double bonds. The formation of double bonds at heavy ion radiolysis is explained by HF separation. The optical density changes for different types of polymers under the same conditions of irradiation (film thickness is 20 ~m, 4CAr, N=5.10 n ion/cmZ). F-2 has the maximum value of optical density at A=335 nm. One can conclude that the greater is the hydrogenous fragments (-CH -CF -) in the polymer chain the higher will be the 2
2
radiation yield of double bonds . The increase of absorption over all UV- and visible spectra indicates a great variety of conjugation (two, three or more double bonds with different types of replacement) having an accidental character. Since the etching track rate is connected with the quantity and type of radiolysis products in the given case of all with the quantity of double bonds which are oxidated by etching solution. One can assume that the maximum etching track rate and maximum sensitivity should be observed for the pure PVDF (F-2) that fully corresponds to experimental data. REFERENCES
I. Panshin Yu.A.,Malkevitch S.G.,Dunaevskaya C.S. (1978).Fluoroplastics, "Chemistry", Leningrad. 2. Tretyakova S.P., Shirkova V.V. (1986) Polyvinylidenefluorlde as Charged Particle Detector. Nuclear Tracks, v. 12, N I-6, pp. 75-76, 3. Almasi Gy., Somogyi G. (1981] Range and REL data for light and heavy ions in CR-39, CN-85 and PC nuclear track detectors, ATOMKI Koezlemenyek, N 23, p.99-I12. 4. Socrates G. (1980). Infrared Characteristic Group Frequencies, John Wiley and Sons, New-York.