Thermosetting polymers from phenols of different structure and formaldehyde

2202

V . A . S]~RGEYEVe$ al.

REFERENCES 1. K. A. ANDRIANOV, Polimery s neogranicheskimi glavnymi tsepyami molekul (Polymers with molecules containing inorganic main chains), p. 264, Izd. Akad. Nauk SSSR, 1962 2. K. A. ANDRIANOV, Dokl. Akad. Nauk SSSR 151: 1093, 1963 3. S. V. AVER'YANOV, I. Ya. PODDUBNYI, L. A. AVER'YANOVA and Yu. S. TRENKE, Kauchuk i rezina, 1963, No. 8, 1 4. K. A. ANDRIANOV, L. M. KHANANASHVILI, A. V. BARLAMOV and V. S. TIKHONOV, Plast. massy, 1964, No. 3, 20 5. M. WICK, Kunststoffe 50: 433, 1960 6. K. A. ANDRIANOV and A. A. ZHI)ANOV, Izv. Akad. Nauk SSSR, Otd. khim. nauk, 615, 1962 7. A. J. BARRY, J. Appl. Phys. 17: 1020, 1946 8. F. BILLMEYER, Vvedenie v khimiyu i tekhnologiyu polimerov (Introduction to the Chemistry and Technology of Polymers), p. 161, (Russian translation), Foreign Literature Publishing House, 1958 9. S. V. AVER'ANOV, I. Ya. PODDUBNYI, Yu. V. TRENKE and L. A. AVER'YANOVA, Kauchuk i rezina, No. 12, 1, 1961 10. V. F. GRIDINA. A. L. KLEBANSKII and V. A. BARTASHEV, ZhVKhO im D. I. Mendeleyeva, 7: 230, 1962 11. V. F. GRIDINA, A. L. KLEBANSKII, V. A. BARTASHEV and V. N. SHAROV, Zh. obshch, khim. 32: 322, 1962 12. M. LAPPERT, Chem. Revs. 56: 959, 1956 13. B. M. MIKHAILOV, Uspekhi khimii 28: 1450, 1959 14. H. STENBERG and D. A. HUNSTER, Ind. Engng. Chem. 49: 174, 1957 15. B. JONES and C. KINNEY, J. Amer. Chem. Soc. 61: 1378, 1939 16. V. F. GRIDINA, A. L. KLEBANSglI and V. A. BARASHEV, Zh. obshch, khim. 34: 14004, 1964 17. A. V. KARLIN, V. M. TROFIMOV and L. A. MITROFANOV, U.S.S.R. Pat. (Author's Certificate) No. 184453; Byull. izobretenii, No. 15, 90, 1966

THERMOSETTING POLYMERS FROM PHENOLS OF DIFFERENT STRUCTURE AND FORMALDEHYDE* V. A. SERGEYEV, V. V. KORSHAK a n d V. K . SHITIKOV Institute of Hetero-organic Compounds, U.S.S.R. Academy of Sciences

(Received 26 August 1966) PlCrENOLFORMATJDEHYDE p o l y m e r s h a v e f o u n d e x t e n s i v e a p p l i c a t i o n as p a i n t v e h i c l e s , l a c q u e r s etc. I n t h i s c o m m u n i c a t i o n p o l y m e r s b a s e d on fluorescein, a-naphtholphthalein, o-cresolphthalein, phenolphthalein, 1,1-bis-(p-hydroxyphenyl) cyclohexane and d i h y d r o x y d i p h e n y l are described a n d their heat resistance * Vysokomol. soyed. A9: No. 9, 1952-1957, 1967.

Thermosetting polymers from phenols

2203

is studied. The polymers from fluoroscein, o-cresolphthalein and ~-naphtolphthalein have not been prepared previously. TABLE

I.

RESULTS

OF

THERMOGRAVIMETRIC OF

TESTS

DIFFERENT

Yield

ON

PHENOLFORMALDEHYDE

E l e m e n t a r y analysis, O,o

o£fonPolymer

T* 1

T*

ized polyfrier,

% FluoreseeinformMdehyde o-Cresolphthaleinformaldehyde a-Naphtholphthaleinformaldehyde Phenolphthaleinformaldehyde Dihydroxydiphenylformaldehyde 1,1-bis-(p-Hydroxyphenyl)formaldehyde Phenol formaldehyde PhenolformMdehyde novolak

POLYMERS

STRUCTURE

I

polymer

o (difference)

tt

carbonized polymer

_

!

C

0 (difference)

tI ]

Yield of carbon

[16], O/ O

340 460

51.5

67"05' 4"37: 28.58

95.58 0.91!

3"51

73"4

350 525

53"0

77"98 4"55

88.50 1.13i 10-37

60"1

17.47

J 295 455

40.2

425

515

59.0

73"73 4"60

415 565

60.0

73"02 6"02: 20'96

179"78 4"18 16.04 I I

22-22

1.20

21'67

1.021 3"29 92.86

0"77

95'26

0.68!

38'5 76'6

6"37

76'3

4"06

70'3

2-31

34"7

I i i

355 380 I 455 535

10.5 57.6

76'74 7.48 78"001 5"90

17.58 16.00

--i

1I

9O 185

28.2

78"60 5-87

15.53 i

!96.75

i

0.94

* T1 and T~ are the temperatures at which the polymer samples lose 10% and 20% of their weight respectively

In contrast to phenol all the above phenols of complex structure are insoluble in water. Therefore polycondensation with excess formaldehyde to produce resins was carried out in solution in n-propalml or dimethylformamide, with aqueous ammonia as catalyst. Moreover methyl derivatives of phneolphthalein have been obtained by reaction of phenolphthalein with formaldehyde in aqueous NaOH solution [1]. For determination of the heat resistance of the polymers we used various methods of pyrolytic decomposition, but attention was paid mainly to the thermogravimetric method. Table 1 presents the results of thermogravimetric studies of phenolformaldehyde polymers of different structure. The polymers were heat treated in an atmosphere of argon at 900 ° for 60 rain. It is seen from Table 1 that all the polymers except the novolak and the polymer from 1,1-bis-(p-hydroxyphenyl)cyclohexanegive a high yield of carbonized polymer. The polymer from dihydroxydiphenyl gives a higher yield of carbonized polymer than the phenolformaldehyde polymer. This can be explained

2204

V . A . S E R G E Y E V et ag.

by the fact that with the same degree of crosslinking of the two products the polymer from dihydroxydiphenyl contains a smaller number of methylene groups than the phenolformaldehyde polymer. It is well known that in thermal TABLE 2. COMPOSITION OF V O L A T I L E PRODUCTS EVOLVED D U R I N G T H E R M A L DECOMPOSITION OF P H E N O L P H T H A L E I N AND P H E N O L F O R M A L D E H Y D E POLYMERS $

Polymer

Quantity of liquid,

Phenolphthaleinformaldehyde Phenolphormaldehyde

Quantity of

gaseous

%

products, mg/g of polymer

19.2 27.2

288-6 288.0

Composition of gaseous products, mg/g of polymer

Ha

149"0 155"2

CH4

CO

COs

34"9 73"4

25"2 45"0

31-5 2"5

COs % of theory

61"0

* Polymers heated to 900° in 1 hr.

and thermal-oxidative treatment of phenolformaldehyde polymers breakdown at the methylene groups occurs first, with evolution of methane [2-10], but benzene nuclei at high temperatures tend to give carbonized polymer (coked residue) in high yield (2, 4,10, 11]. Thus when dihydroxydiphenyl is used in place of phenol for synthesis of phenolformaldehyde polymers products of higher heat resistance are produced. It is also seen from Table 1 that the phenolphthaleinformaldehyde polymer gives a high yield of carbonized polymer. The notable feature of this polymer is that on heat treatment the highest proportion of carbon is retained in the carbonized polymer. Consequently greatest attention was subsequently paid to study of the properties, especially the heat resistance, of polymers based on phenolphthalein. When these polymers are heat treated liquid and gaseous products are formed in addition to a large quantity of carbonized polymer. Data on this are presented in Table 2, where for comparison the results of a study of the liquid and gaseous products evolved during decomposition of a phenolformaldehyde polymer are also given. It is seen from Table 2 that the quantity of liquid products evolved during pyrolysis of the phenolpthalein formaldehyde polymer is less than from pyrolysis of the phenolformaldehyde polymer, and the gaseous products from pyrolysis of the former polymer contain a considerable quantity of carbon dioxide The formation of carbonized polymer is a property not only of phenolphthalein polymers, but also of phenolphthalein itself. For example, Maksorov [12] has mentioned resinification of phenolphthalein at temperatures above its melting point. We studied the behaviour of phenolphthalein at 290 ° and 390 ° (Table 3).

Thermosetting polymers from phenols

2205

TABLE 3. PRODUCTS EVOLVED DURING DECOMPOSITIONOF PHENOLPHTHALEIN Solid residue Heat treatment

temperature, °C

Elementary composition, %

~. iYield, -~ %

C

-8

O (differ-

M

4~

solubility in acetone

Z

Yield of liquid products, %

Gaseous products

ence)

290, in nitrogen

5

290, ditto

16

7"26 6"94 1"87

81"1 78"0 78.13

3.8(

18.01

Soluble

17.4

6.8

6'6

Ditto

19.0

18.2

9"5

23.1

14.5

13-7

31.6

45.7

49.2

1"22

290, ,, 290, in air 390, in nitrogen

19 24

0 0

75'2 75.57

20.56

3.8,

Soluble to 46.6o~) Insoluble

60"0 82-60 3"83 13.57

I t is seen f r o m Table 3 t h a t d e c o m p o s i t i o n of p h e n o l p h t h a l e i n p r o d u c e s a solid residue a n d a t the same time liquid a n d gaseous p r o d u c t s are evolved. The yield o f solid residue falls a n d its c a r b o n c o n t e n t increases to 82.6% with increase in /0#

#0

gO !

I

O fO0

I

I

300

500

I

,

7OO ~°G

FIG. 1. Thermogravimetric curves of phenolphthalein (1) and of the solid residues from

decomposition of the latter at 290° (2) and 390° (3). t h e t e m p e r a t u r e a n d time of h e a t t r e a t m e n t . The h y d r o x y l c o n t e n t of t h e reaction m i x t u r e falls w i t h t i m e o f h e a t t r e a t m e n t a n d after 24 hr a t 290 ° t h e solid residue contains p r a c t i c a l l y n o h y d r o x y l groups. The m a j o r gaseous p r o d u c t o f

2206

V. A. SEBO~,YEV et al.

decomposition ofphenolphthalein is carbon dioxide. The quantity of this increases with increase in the time and temperature of heat treatment, but it does not exceed 50% of theory. The solid residue formed at 390 ° does not contain molecules capable of being converted by aqueous alkali to a coloured quinonoid structure. This obviously indicates quantitative decomposition of the phenolphthalein. Study of the volatile :products evolved at 390 ° showed that in the decomposition of 1 mole of phenolphthalein 1 mole of phenol and 0.5 mole of CO~ are liberated. The behaviour of phenolphthalein at high temperatures was also studied by means of thermogravimetric analysis. Figure 1 shows the results of a thermogravimetric study of phenolphthalein and its decomposition products. It is seen tha~ phenolphthalein begins to decompose extensively at 300-320 ° and it decomposes completely when the temperature is raised steadily to 900 ° over a period of 1 hr. When phenolphthalein is previously heated to 290 ° or 390 ° the decomposition curves change sharply. Extensive loss in weight then occurs at higher temperatures (400-450 °) and a carbonized polymer, stable at 900 °, is formed in yields of 45.5% and 52.4%. The explanation of this is that in heat treatment of phenolphthalein with rapid rise in temperature to 900 ° the poly-

~/00 _~80

N g tOO

JO0

,~OO

T,° C

FIO. 2. TheFmogravimetriccurves of phenolphthaleinformaldehyde (1) and phenolformaldehydo (2) polymers. condensation leading to formation of a carbonized polymer does not go to completion. The previous heat treatment at 290 ° and 390 ° obviously promotes extensive polycondensation. Previous polycondensation of phenolphthalein with formaldehyde also provides a means of crosslinking the phenolphthalein molecules and consequently of increasing the yield of carbonized polymer. Polymers from phenolphthalein and formaldehyde were first prepared by Kienle in 1930 [13], and a little later by Zelinskii and Maksorov [14]. Bafna and Shah [15] used phenolphthalein as a raw material for production of ion-exchange resins. We have prepared phenolphthalein formaldehyde polymers of both the resin and novolak types. Figure 2 shows thermogravimetric curves of the decomposition of a hardened phenolphthaleinformaldehyde polymer (curve 1) and, for comparison, of a phe-

Thermosetting polymers from phenols

2207

nolformaldehyde polymer (curve 2). Both polymers begin to decompose extensively at 3500-360 ° but the phenolphthaleinformaldehyde polymer gives a higher yield of carbonized polymer at 900 ° than the phenolformaldehyde polymer. Differential heat-effect curves (Fig. 3) obtained from heat treatment of the phenolphthalein- and phenolformaldehyde polymers, and also their rates of decomposition (Fig. 4), determined by the derivatograph system of Paulik,

\

Z

FIO. 3. Differential heat effect curves of phenolphthalein formaldehyde (1) and phenolformaldehyde (2) polymers. Paulik and Erdey, show that for the phenolphthaleinformaldehydepolymer there is clearly seen a characteristic temperature region around 360 ° in which a thermal process associated with absorption of heat occurs. The maximal rate of decomposition of the phenolphthaleinformaldehydepolymer is reached in the same temper5//0 °

475°~l

~00

,?00

g00

"lOg

,900

FIG. 4. Rate of weight loss of phcnolphthaleinformaldehyde (1) and phenolformaldehyde (2) polymers. ature region. This indicates that breakdown of the lactone ring in the phenolphthalein polymer occurs at 350-370 ° under the chosen conditions of heat treatment. Study of the infrared spectra of phenolphthalein formaldehyde polymers, obtained by gradual heating of the methylol derivatives of phenolphthMein to 180° and above, showed that the process of hardening of these polymers is similar

2208

V. A. SERGEYEV et a~.

g 6

3 /

//~)

\%

go0 JO0 700 900 T,°C Fzo. 5. Temperature dependence of the rate of gas evolution for phenolphthaleinformal. dehyde (1) and phenolformaldehyde (2) polymers. to t h a t of phenolformaldehyde polymers. The band of the carbonyl group of the lactone ring of pheno!phthalein (1760 cm -1) decreases markedly at 330 °, however. The temperature dependence of the rate of gas evolution when phenolphthaleinformaldehyde and phenolformaldehyde polymers are heated to 900 ° in 1 hr (Fig. 5) shows a difference between the two polymers in t h a t before the pyrolysis temperature of the polymer a considerable quantity of gas (mainly C02) is evolved by the former. The CO 2 evolved up to 600 ° is about 98% of the total quantity produced by heat treatment of the phenolphthaleinformaldehyde polymer up to 900%, which is 61% of the theoretical quantity (Table 2). Thus quantitative evolution of CO 2 does not occur at the temperature of breakdown of the lactone ring of the phenolphthaleinformaldehyde polymer. This indicates t h a t the lactone ring reacts with the methylol groups or with the aromatic part of the polymer molecule, thus increasing the degree of crosslinking of the polymer. Further extensive gas evolution occurs in the region of 600-700 ° in both polymers. This is evidently associated with the carbonization process because at this stage the major quantities of methane and hydrogen are evolved. CONCLUSIONS

(1) Polymers based on o-cresolphthalein, a-naphtholpthalein, fluorescein, 1,1bis-(p-hydroxyphenyl)cyclohexane and dihydroxydiphenyl have been synthesized and their properties have been studied. (2) I t was found t h a t polymers containing lactone groups are heat resistant and give high yields of carbonized polymers. Translated by E. O. PHZLLIPS REFERENCES 1. V. V. KORS]~LK, V. A. SERflEVEV, V. V. SH~T]ICOV, V. F. BURLUTSKff, I. ~Lh. BELY-

AKOVA and S. G. ZHELTAKOVA, U.S.S.R. Pat. (Author's Certificate) No. 172489; Byull. izobret., :No. 13, 70, 1965 2. V. V. KORSHAK, V. A. SERGEYEV, L. V. KOZLOV and L. I. KOMAROVA, Plast. massy, ~To. 2, 33, 1966

Chain transfer rate constants in polymerization of styrene

2209

3. Yu. Ye. DOROSHENKO, V. V. K O R S H A K and V. A. SEttGEYEV, Plast. massy, No. 8, 9, 1965 4. K. D. JEFFREYS, British Plastics 36: 188, 1963 5. G. F. ItEItON, Symposium on Heat-resistant Polymers, London, 21-23 September, 1960 6. G. F. HERON, Soc. Chem. Ind. Monograph No. 13, 475, 1961 7. R. T. CONLEY, Prec. Battelle Syrup. Thermal Stability of Polymers, p. 68, Columbus, Ohio, 1963 8. It. T. {1ONLEY and I. F. BIEIt0N, J. Appl. Polymer Sci. 7: 183, 1963 9. R. T. CONLEY and I. F. BIERON, J. Appl. Polymer Sci. 7: 171, 1963 10. K. OUCHI and It. ttONDA, F e u l 38: 429, 1956 11. H. C. ANDERSON, S P E Trans. 2: 202, 1962 12. B. V. MAKSOttOV, Byull. plastmasstroya, vol. 1, Nos. 1-2, 6, 1931 13. It. It. KIENLE, Ind. Engng. Chem. 22: 590, 1930 14. N. D. ZELINSKII a n d B. V. MAKSOItOV, Ind. Engng. Chem. 24: 63, 1932 15. S. L. BAFNA a n d It. A. SHAH, J. I n d i a n Chem. Soc. 29: 611, 1952; I n d i a n Pat. No. 44359, 1952; Chem. Abs., 798, 1953 (Translated in Polymer Sci. U.S.S.R. 8: 10, 1912, 1966) 16. Yu. Ye. DOItOSHENKO, V. V. KOItSHAK, V. A. SERGEYEV and Z. CHAPKA, Vysokernel, soyed. 8: 1787, 1966 (Translated in Polymer Sci. U.S.S.R. 8,10, 1912, 1966)

INITIATION AND CHAIN TRANSFER RATE CONSTANTS IN POLYMERIZATION OF STYRENE IN THE PRESENCE OF DIFUNCTIONAL PEROXIDES * t V. V. ZAITSEVA, V. D . YENAL'EV a n d A . I . YURZI~ENKO Ukrainian Plastics Research I n s t i t u t e I. I. Mechnikov State University, Odessa (Received 27 August 1966)

IT gAS been shown previously that di-(tert.-alkylperoxy)alkanes are very efficient initiators of the polymerization of styrene and can be used for preparation of graft and block copolymers [1, 2]. I t seemed of interest to study in detail the initiating efficiency of di-(tert.-butylperoxy)alkanes in the polymerization of styrene with the objective of extensive use of these as sources of free radicals at temperatures below 100% Despite the fact that threre are a large number of peroxides that decompose below 100 ° the di-(tert.-alkylperoxy)alkanes are interesting because their decomposition yields free radicals containing a peroxide group [2]. As a result of reaction of these radicals with monomer molecules or * Vysokomol. soyed. A9: No. 9, 1958-1962, 1967. t Communication I in the series " S t u d y of difunctional peroxides in polymerization of styrene".