- Email: [email protected]
Intermediate products of the oxidation of polycarbonate
1368
A . I . SII)NEV et al. REFERENCES
]. W. H. HUNTER, et o~., J. Amer. Chem. Soe. 39: 2640, 1917; 48: 151, 1926; 54: 2459, 1932; 55: 3701, 1933 2. O. SUIS, Liebig's Ann. Chem. 598: 121, ]956 3. L. WALL, Rubber World 139: 307, 1958 4. M. J. S. D E W A R and A. JAMES, J. Chem. Soc., 917, 1958 5. C. C. PRICE and G. D. STAFFIN, J. Amer. Chem. See. 82: 3632, 1960 6. A. S. HAY, Fortsch. Hochpol. Forsch. 4: 496, 1967; T. KUNITAKE, J . See. OrgaB. Synth. Chem. J a p a n 22: 755, 1966; J. BIALY, Polymer 12: 1, 1967 7. S. GOLDSCHITT, Chem. Ber., 90: 19, 1957 8. R. G. R. BACON, J. Chem. See., 1339, 1960 9. C. G. HAYNES, J. Chem. See., 2823, 1956 10. W. BRACKM.AN, Rec. tray. chim. 74: 931, 1955 11. C. MARTIUS, Liebig's Ann. Chem. 607: 159, 1957 12. K. DIMROTH, Chem. Ber. 1OO: 132, 1967 13. A. S. HAY, H. S. BLANCHARD, et al., J. Amer. Chem. Soc. 81: 6335, 1959 14. Dutch Pat. 6403374, Chem. Abstrs. 64: 9836D, 1966 15. Dutch P a t 6403375 Chem. Abstrs. 64: 9836E, 1966 16. D. SUGITA, J. Chem. Soc. Japan, Pure Chem. See., 86: 607, 1966 17. U. S. Pat. 3236807, Chem. Abstrs. 64: 14386F, 1966 18. J. R. HALL, J. Polymer Sei. 4B: 463, 1965 19. U. S. Pat. 3219625, Chem. Abstrs, 64: 8094F, 1966 20. U. S. Pat. 3219626, Chem. Abstrs. 64: 8095A, 1966 21. C. C. PRICE and W. H. BUTTE, J. Amer. Chem. Soc. 84: 3567, 1962 22. G. D. COOPER, J. Amer. Chem. See. 87: 3996, 1965 23. E. MeNELIS, J. Organ. Chem. 31: 1255, 1966 24. C. L. SEGAL, J. Polymer Sci. 4B: 80, 1966 25. F. LABORIE-GARDEUX, Compt. rend. 263: 1352, 1966 26. V. V. KOPYLOV and A. N. PRAVEDNIKOV, Vysokomol. soyed. BI0: 254, 1968 (No~ translated in Polymer Sei. U.S.S.R.)
INTERM_EDIATE PRODUCTS OF THE OXIDATION OF POLYCARBONATE* A . I . SIDI~'EV, A . I~T. PRAVEDlCIKOV a n d B . M. K O V A R S K A Y A
L. Ya. Karpov .Physieochemleal Institute (Received 24 July 1967) I X PR~.VIOUS p a p e r s [1--4] i t w a s s h o w n t h a t t h e t h e r m o o x i d a t i v e d e g r a d a t i o n o f p o l y c a r b o n a t e (PC) is a c h a i n r a d i c a l p r o c e s s w h i c h is a c c o m p a n i e d b y t h e o x i dation of methyl groups and the decay of ester groups. The decomposition of the * Vysokomol. soyed. A10: No. 5, 1178-1182, 1968.
Intermediate products of oxidation of polyearbonate
1369
l a t t e r is a h y d r o l y t i c process due to t h e presence o f w a t e r f o r m e d as a result o f o x i d a t i o n [3, 4]. I t was f o u n d t h a t no appreciable a m o u n t s o f h y d r o p e r o x i d e are formed. H o w e v e r it is also k n o w n t h a t t h e o x i d a t i o n of low-molecular a r o m a t i c h y d r o c a r b o n s c o n t a i n i n g different alkylene groups b e t w e e n t w o benzene rings proceeds a t 175 ° t h r o u g h h y d r o p e r o x i d e s [5,6]. Because of this it was desired to s t u d y p r o d u c t s o f t h e o x i d a t i o n of 2,2-di-(4-hydroxyphenyl)propane(diane) (a model c o m p o u n d t o PC) a n d to c o m p a r e t h e m with p r o d u c t s o f oxidation o f the p o l y m e r itself. EXPERIMENTAL PROCEDURE
The diane was oxidized at 175 and 200° in the flow oxidation apparatus shown in the Figure. The °xygen feed rate was 1000 ml/min. The polycarbonate (PC) was oxidized at 300° under similar conditions. The volatile decomposition products were collected in traps 6a,b,c. The reaction products collected in the first trap in the series 6a were those condensing at room temperature and mainly consisted of aromatic hydrocarbons; the reaction products condensing at the temperature of dry ice were collected in the other traps of the series 6a: these were oxygen-containing aliphatie products. Gaseous products were passed through a saturated Ba(OH~) solution in traps of the series 6b and 6c with the result that CO2 was absorbed and BaCOa precipitated. Other gaseous products containing CO and 02 were passed over cupric oxide in the coffer 7 heated up to 700° where CO was oxidized to CO~ which was absorbed in the manner described above. Barium carbonate was decomposed by means of iced acetic acid and the CO2 was analysed by the volumetric method. The oxygen-containing oxidation products were identified by chromatography on a column 3.5 m long containing silica gel. The stationary phase was the relatively weakly-polar fl-dipropionitrile ether. The temperature of the column was 60° and the rate of flow of the gas-carrier (helium), 25 ml/min. The aromatic decomposition products were identified and separated on the column (length 3 m) of a "Tsvet" chromatograph with celite as the carrier and apiezon-A as the stationary phase. Aromatic degradation products with b.p. above 200° were separated by means of a "Griffin" chromatograph: the column length was 1.8 m; stationary phase--0.1% silicone oil on powdered glass (40 mesh); column temperature-- 190°; gas-carrier (helium) rate-- 30 ml/min. The content of hydroperoxides was determined iodometrically. The polymer was oxidized under static conditions following the procedure described in [7] at 300% initial oxygen pressure-- 640 mmHg. DISCUSSION OF RESULTS
T h e results o f t h e analysis o f p r o d u c t s o f the oxidation o f diane a n d polycarb o n a t e are given in Table 1, T h e p r i m a r y p r o d u c t of t h e o x i d a t i o n of diane a n d of the m a j o r i t y of low-molecu l a r h y d r o c a r b o n s are h y d r o p e r o x i d e s (Table 2), a n d their f u r t h e r decomposit i o n gives rise to radical a u t o c a t a l y t i c acceleration of t h e reactions [8]. On the o t h e r h a n d we k n o w as t h e o x i d a t i o n t e m p e r a t u r e rises the role o f the isomeriz a t i o n o f alkylperoxide radicals becomes m o r e i m p o r t a n t , which in t u r n reduces t h e r a t e o f a c c u m u l a t i o n , o f h y d r o p e r o x i d e s . T h e m a g n i t u d e o f t h e competing r e a c t i o n o f t h e isomerization of alkylperoxide radicals relative to the f o r m a t i o n o f h y d r o p e r o x i d e s increases as t h e o x i d a t i o n t e m p e r a t u r e rises. T h e a c t i v a t i o n
1370
A.I.
S I D N E y et cd.
TABLE I. PRODUCTS 01~ THE OXIDATION OF POLYCARBONATE ( P C ) AT 3 0 0 ° A m ) OF D L ~ T E AT 1 7 5 °
(Oxygen feed rate 1000 ml/min)
Decomposition product
Oxidation of PC under static conditions,
Po~=
64
Oxidation of Oxida- OxidaOxida- OxidaPC tion of tion of tion of tion of diane Decomposition under PC diane PC static under under product under under condi- flow con- flow conow con Low contions, ditions ditions ditions ditions P o 2= 6 4 0
~nHg
mmHg
C02 CO R00H
HCH0 CHaCH0 CHaCOCHa CH30H CH,C00H HCOOH
÷ +
÷ +
Traces
+ ÷
Ditto
÷ ÷ + + ÷
H~0 C~H~
C~-Is0H C~HsCH, C,H,C,H, C,H~CH(CH,), C~H,CH0 C,H~CHO
Traces
+
÷ + +
Diane
+ + + + q+ + ÷ +
+ + + + + + + + +
+ + +
+ +
* _Notation: + , product is present; --, is not present,
e n e r g y for the m o n o m o l e c u l a r reaction of t h e isomerization of a l k y l p e r o x i d e radicals is a b o u t 20 keal/mole, while t h a t for the bimolecular r e a c t i o n o f the form a t i o n of h y d r o p e r o x i d e is 10 kcal/mole [8, 10]. Simple calculations show t h a t a t 175 ° the ratio o f the reaction rates for t h e isomerization a n d for t h e f o r m a t i o n T A B L E ~. H Y D R O P E R O X I D E S
CONTENT
AND
WEIGHT
LOSS OF D I A N E UNDER DIFFE1LENT CONDITIONS
Hydroperoxides
Temperature, °C
Weight loss, %
175 200
12 18
content,
R O O H mole/ / d i a n e mole 0.17 0.12
o f h y d r o p e r o x i d e s is close to unity, while a t 300 ° this ratio a m o u n t s to several thousands, i.e. the isomerization reaction becomes practically t h e sole m e a n s o f converting the peroxyradicals. T h e isomerization of p r i m a r y alkylperoxide radicals is t h e r e f o r e m o r e p r o b a b l e t h a n the f o r m a t i o n of peroxide u n d e r the t e m p e r a t u r e conditions a d o p t e d for t h e o x i d a t i o n of p o l y e a r b o n a t e .
Intermediate products of oxidation of polyearbonate
1371
In most cases [8-10] the isomerization of alkylperoxide radicals results in the formation of various oxygen-containing products, some of which are efficient chain-branching agents. The presence of isomerization in these systems is an important stage and in some cases the determining stage as regards the overall rate and the course of oxidation. In study of the kinetic relations in the thermooxidative degradation of polycarbonate [1] it was shown that the rate of decomposition of the polymer i n v a c u o is increased if the polymer is subjected to preliminary oxidation for a short time. Besides this it was shown in [3] that high-molecular oxygen-containing decomposition products undergo further conversion, and the amount of these products in the T A B L E 3. COMPOSITION OF GASEOUS PRODUCTS OF THE THERMAL DECOMPOSITION OF POLYCARBONATE (~O) THAT HAS UNDERGOI~-E PRELIMINARY OXIDATION FOR 1 5 0 ~ N AT 300 °, AT P 0 i ~ 5 5 8 mmI-Ig
Decomposition product laco 18co 1602
leO18O 1802
16CO~ 16COX~O ISCO2 Altogether
Total amount of Amount of product of varyproduct, % ing isotopic composition, % 10 13 1.6 2-4 1-0 72
23.0 5.0 72.0 100
polymer starts to decrease with decreasing oxygen concentration. Comparison of the products formed in the degradation of polycarbonate under different conditions (Table 1) shows that aldehydes undergo further oxidation, and the amount of aldehydes when the polymer is oxidized under static conditions is much reduced compared with the amount in the products of oxidation in the oxidizing apparatus. In order to determine the structure of the intermediate oxygen-containing high-molecular products of oxidation which are responsible for the accelarated rate of thermal decomposition of the polymer i n v a c u o [1] a study was made of the gaseous products of pyrolysis of PC which had been subjected to preliminary oxidation b y oxygen enriched with isotope isO. The procedure was described in [3]. The results of the analysis of gaseous products of the thermal degradation of PC that had undergone preliminary oxidation are given in Table 3, which shows that the main decomposition products are CO and CO s . The ratio of the isotopic composition for 16CO and 18CO shows that carbon
1372
A.I. S1D~v
et
al.
monoxide is formed almost entirely as a result of the decomposition of oxygencontaining products of oxidation, and not as a result of the decay of ester bonds. At the same time isotope 1sO is not present in the carbon dioxide, which shows t h a t the latter is formed solely from ester bonds in the degradation process. This is quite understandable, taking into account t h a t no oxygen is present in the decomposition, and that CO 2 is formed solely through the further oxidation of aldehyde groups. The ratio of the isotopic composition of the oxygen formed in the decomposition of the polymer is similar to the isotopic composition of the initial oxygen. Consequently oxygen is not formed in the decay of ester groups, as in the decomposition of polycarbonate exposed to ionizing irradiation [11], when oxygen was detected in the gaseous products of degradation. The presence of insignificant amounts of oxygen under these conditions m a y be attributed to the partial recombination of tertiary alkylperoxide radicals taking place along with the formation of molecular oxygen. Thus Traylor and Bartat [12] showed clearly that in the oxidation of cumene by oxygen enriched with 1sO alkylpcroxide radicals recombine by the reaction:
J--~
--'\-/
CH3
CH 3
CHs CHs
CH3
c_~,O
I
CHs
CH~ ~O_C_J
%,+ o o
I \=/
CHa
A similar reaction appears to be possible with polycarbonate:
H3C--C--CH~06 + 60--CH2--C--CH.-~
/
\C>-
-+H3C.~C--CH~--O--O--CH2--C--CHs q- 02
In view of the above considerations we conclude therefore that at 250-300 ° the oxidation of polycarbonate starts to develop at an appreciable rate along with the formation of alkylperoxide radicals. Isomerization of the latter results in the formation of a number of intermediate low-molecular and high-molecular earbonyl type products which undergo further conversions and participate in the development of the reaction.
Intermediate products of oxidation of polycarbonate 2
3
1373
lg
///\,\
7
General arrangement of oxidizing apparatus: 1-- cylinder containing oxygen; 2 -- drying system; 3--rheometer; 4--reactor; 5--oxygen enters ~eactor; 6--traps; 7--heater with cupric oxide; 8--coiler for collecting CO2; 9 - gas buret; 10--vacuum stopcocks; //--funnel containing iced acetic acid. In the light of these data the hydroperoxide mechanism of polycarbonate oxidation proposed b y Lee [13] is improbable and unconvincing, particularly as the author includes in the scheme the isomerization of alkyl radicals which requires considerably higher activation energy than the formation of alkylperoxide radicals: l ~ - O 2 - > R O ( ) , ( E = 0 ) and could not be of any real importance in the presence of oxygen [8, 9]. CONCLUSIONS
(1) The oxidation of 2,2-di-(4-hydroxyphenyl)propane is a chain radical process which develops through hydroperoxides. The stationary concentration of the latter decreases as the oxidation temperature rises. (2) The thermooxidative degradation of polycarbonate is a chain radical process which proceeds with the formation of alkylperoxide radicals. Further isomerization of the latter results in the formation of a number of oxygen-containing carbonyl type products, which undergo further conversions during the degradation process and participate in the development of the reaction. Translated by RI J. A. HEI~DRY REFERENCES
1. B. M. KOV~_.RSIT~YA, M. S..~KUT]N, A. I. SIDNEV, 1V[. P. YAZV[KOVA and M. B. NEI-I~AN, Vysokomo]. soyed. 5: 649, 1963 2. M. S. AKUTIN, V. N. KOTRELEV, B. M. KOVARSKAYA, Ye. D. KOSTRYUKOVA, V. V. TARASOV, A. I. SIDNEV, E. RODIN, O. N. NITCHE and M. B. NEIMAN, Plast. massy 6: 26, 1963 3. A. I. SIDNEV, A. S. TELESHOVA, B. M. KOVARSKAYA and A. N. PRAVEDNIKOV, Vysokomol. soyed. 9B: 134, 1967
1374
O.V. LIP.~TOVet al.
4. A. I. SIDNEY, B. M. KOVARSKAYA and A. N. PRAVEDNIKOV, Vysokomol. soyed. 9B: 129, 1967 (Not translated in Polymer Sci. U.S.S.R.) 5. M. S. EVENTOVA, Vestn. Mosk. State Univ. "Khimiya", No. 2, 72, 1961 6. M. S. EVENTOVA, Oxygen Oxidation of Hydrocarbons in the Liquid Phase (in Russian), puhl. by AN SSSR, 1959 7. M. B. NEIMAN, B. M. KOVARSKAYA, M. P. YAZVIKOVA, A. I. 8IDNEV and M. S. AKUTIN, Vysokomol. soyed. 3: 602, 1961 (Not translated in Polymer Sci. U.S.S.R.) 8. N.N. SEMENOV, O nekotorykh problemakh khimicheskoi kinetiki i reaktionnoi sposobnosti {Problems of Chemical Kinetics and Reactivity) (in Russian). publ. by AI~ SSSR, 1958 9. A. FISH, Quart. Rev. 18: 243, 1964 10. V. B. MILLER, M. B. NEIMA~, V. S. PUDOV and L. I. LAFER, Vysokomol. soyed. 1: 696:1959 (Not translated in Polymer Sci. U.S.S.R.) 11. I. H. GOLDEN and E. A. HARELL, J. Polymer Sci. AI: 1671, 1963 12. T. G. TRAYLOR and P. D. BARTAT, Tetrahedron Letters, 24, 30, 1960 13. L. LEE, J. Polymer Sci. A2: 2859, 1964
EFFECT OF MANUFACTURING CONDITIONS ON THE STRUCTURE AND BEHAVIOUR OF POLYVINYLCHLORIDE FILMS* O. V. LIPATOV, 1~/[. B. KONSTANTII~OPOL'SKAYA, 1~. S. MONASTYRSKAYA,Z. YA. ~BERESTNEVAa n d V. A. KARGIN L. Ya. Karpov Physicochemical Institute Moscow Technological Institute for Light Industry
(Received 27 July 1967)
MA~¥ papers dealing with the relationship between mechanical properties and structure of polymers have recently shown that physical and mechanical properties are largely determined by the level of supermolecular organization [1-3]. It is well known that a morphological secondary structural film pattern is observed in polyvinylchloride (PVC) obtained by stereospecifle polymerization, which is typical of crystalline polymers [4]. Polymer chain ordering was also found in PVC of irregular structure formed by free radical polymerization. The association of PVC molecules in methylethylketone and other solvents was studied by Hengstenberg and Sehuch~[5]. They noted that the formation of associates is influenced by the solvent, the dissolving process and molecular weight. By sedimentation analysis, viscometry, electron microscopy and the low-angle X-ray method, the transverse dimensions of associates were determined. They are in the range of 70-80 A, according to low-angle X-ray method and 120-160 A, according to sedimentation and electron microscope data. In addition, in irregular PVC [6, 10] the formation of spherulites of up to * Vysokomol. soyed. A1O: No. 5, 1183-1190, 1968.
A . I . SII)NEV et al. REFERENCES
]. W. H. HUNTER, et o~., J. Amer. Chem. Soe. 39: 2640, 1917; 48: 151, 1926; 54: 2459, 1932; 55: 3701, 1933 2. O. SUIS, Liebig's Ann. Chem. 598: 121, ]956 3. L. WALL, Rubber World 139: 307, 1958 4. M. J. S. D E W A R and A. JAMES, J. Chem. Soc., 917, 1958 5. C. C. PRICE and G. D. STAFFIN, J. Amer. Chem. See. 82: 3632, 1960 6. A. S. HAY, Fortsch. Hochpol. Forsch. 4: 496, 1967; T. KUNITAKE, J . See. OrgaB. Synth. Chem. J a p a n 22: 755, 1966; J. BIALY, Polymer 12: 1, 1967 7. S. GOLDSCHITT, Chem. Ber., 90: 19, 1957 8. R. G. R. BACON, J. Chem. See., 1339, 1960 9. C. G. HAYNES, J. Chem. See., 2823, 1956 10. W. BRACKM.AN, Rec. tray. chim. 74: 931, 1955 11. C. MARTIUS, Liebig's Ann. Chem. 607: 159, 1957 12. K. DIMROTH, Chem. Ber. 1OO: 132, 1967 13. A. S. HAY, H. S. BLANCHARD, et al., J. Amer. Chem. Soc. 81: 6335, 1959 14. Dutch Pat. 6403374, Chem. Abstrs. 64: 9836D, 1966 15. Dutch P a t 6403375 Chem. Abstrs. 64: 9836E, 1966 16. D. SUGITA, J. Chem. Soc. Japan, Pure Chem. See., 86: 607, 1966 17. U. S. Pat. 3236807, Chem. Abstrs. 64: 14386F, 1966 18. J. R. HALL, J. Polymer Sei. 4B: 463, 1965 19. U. S. Pat. 3219625, Chem. Abstrs, 64: 8094F, 1966 20. U. S. Pat. 3219626, Chem. Abstrs. 64: 8095A, 1966 21. C. C. PRICE and W. H. BUTTE, J. Amer. Chem. Soc. 84: 3567, 1962 22. G. D. COOPER, J. Amer. Chem. See. 87: 3996, 1965 23. E. MeNELIS, J. Organ. Chem. 31: 1255, 1966 24. C. L. SEGAL, J. Polymer Sci. 4B: 80, 1966 25. F. LABORIE-GARDEUX, Compt. rend. 263: 1352, 1966 26. V. V. KOPYLOV and A. N. PRAVEDNIKOV, Vysokomol. soyed. BI0: 254, 1968 (No~ translated in Polymer Sei. U.S.S.R.)
INTERM_EDIATE PRODUCTS OF THE OXIDATION OF POLYCARBONATE* A . I . SIDI~'EV, A . I~T. PRAVEDlCIKOV a n d B . M. K O V A R S K A Y A
L. Ya. Karpov .Physieochemleal Institute (Received 24 July 1967) I X PR~.VIOUS p a p e r s [1--4] i t w a s s h o w n t h a t t h e t h e r m o o x i d a t i v e d e g r a d a t i o n o f p o l y c a r b o n a t e (PC) is a c h a i n r a d i c a l p r o c e s s w h i c h is a c c o m p a n i e d b y t h e o x i dation of methyl groups and the decay of ester groups. The decomposition of the * Vysokomol. soyed. A10: No. 5, 1178-1182, 1968.
Intermediate products of oxidation of polyearbonate
1369
l a t t e r is a h y d r o l y t i c process due to t h e presence o f w a t e r f o r m e d as a result o f o x i d a t i o n [3, 4]. I t was f o u n d t h a t no appreciable a m o u n t s o f h y d r o p e r o x i d e are formed. H o w e v e r it is also k n o w n t h a t t h e o x i d a t i o n of low-molecular a r o m a t i c h y d r o c a r b o n s c o n t a i n i n g different alkylene groups b e t w e e n t w o benzene rings proceeds a t 175 ° t h r o u g h h y d r o p e r o x i d e s [5,6]. Because of this it was desired to s t u d y p r o d u c t s o f t h e o x i d a t i o n of 2,2-di-(4-hydroxyphenyl)propane(diane) (a model c o m p o u n d t o PC) a n d to c o m p a r e t h e m with p r o d u c t s o f oxidation o f the p o l y m e r itself. EXPERIMENTAL PROCEDURE
The diane was oxidized at 175 and 200° in the flow oxidation apparatus shown in the Figure. The °xygen feed rate was 1000 ml/min. The polycarbonate (PC) was oxidized at 300° under similar conditions. The volatile decomposition products were collected in traps 6a,b,c. The reaction products collected in the first trap in the series 6a were those condensing at room temperature and mainly consisted of aromatic hydrocarbons; the reaction products condensing at the temperature of dry ice were collected in the other traps of the series 6a: these were oxygen-containing aliphatie products. Gaseous products were passed through a saturated Ba(OH~) solution in traps of the series 6b and 6c with the result that CO2 was absorbed and BaCOa precipitated. Other gaseous products containing CO and 02 were passed over cupric oxide in the coffer 7 heated up to 700° where CO was oxidized to CO~ which was absorbed in the manner described above. Barium carbonate was decomposed by means of iced acetic acid and the CO2 was analysed by the volumetric method. The oxygen-containing oxidation products were identified by chromatography on a column 3.5 m long containing silica gel. The stationary phase was the relatively weakly-polar fl-dipropionitrile ether. The temperature of the column was 60° and the rate of flow of the gas-carrier (helium), 25 ml/min. The aromatic decomposition products were identified and separated on the column (length 3 m) of a "Tsvet" chromatograph with celite as the carrier and apiezon-A as the stationary phase. Aromatic degradation products with b.p. above 200° were separated by means of a "Griffin" chromatograph: the column length was 1.8 m; stationary phase--0.1% silicone oil on powdered glass (40 mesh); column temperature-- 190°; gas-carrier (helium) rate-- 30 ml/min. The content of hydroperoxides was determined iodometrically. The polymer was oxidized under static conditions following the procedure described in [7] at 300% initial oxygen pressure-- 640 mmHg. DISCUSSION OF RESULTS
T h e results o f t h e analysis o f p r o d u c t s o f the oxidation o f diane a n d polycarb o n a t e are given in Table 1, T h e p r i m a r y p r o d u c t of t h e o x i d a t i o n of diane a n d of the m a j o r i t y of low-molecu l a r h y d r o c a r b o n s are h y d r o p e r o x i d e s (Table 2), a n d their f u r t h e r decomposit i o n gives rise to radical a u t o c a t a l y t i c acceleration of t h e reactions [8]. On the o t h e r h a n d we k n o w as t h e o x i d a t i o n t e m p e r a t u r e rises the role o f the isomeriz a t i o n o f alkylperoxide radicals becomes m o r e i m p o r t a n t , which in t u r n reduces t h e r a t e o f a c c u m u l a t i o n , o f h y d r o p e r o x i d e s . T h e m a g n i t u d e o f t h e competing r e a c t i o n o f t h e isomerization of alkylperoxide radicals relative to the f o r m a t i o n o f h y d r o p e r o x i d e s increases as t h e o x i d a t i o n t e m p e r a t u r e rises. T h e a c t i v a t i o n
1370
A.I.
S I D N E y et cd.
TABLE I. PRODUCTS 01~ THE OXIDATION OF POLYCARBONATE ( P C ) AT 3 0 0 ° A m ) OF D L ~ T E AT 1 7 5 °
(Oxygen feed rate 1000 ml/min)
Decomposition product
Oxidation of PC under static conditions,
Po~=
64
Oxidation of Oxida- OxidaOxida- OxidaPC tion of tion of tion of tion of diane Decomposition under PC diane PC static under under product under under condi- flow con- flow conow con Low contions, ditions ditions ditions ditions P o 2= 6 4 0
~nHg
mmHg
C02 CO R00H
HCH0 CHaCH0 CHaCOCHa CH30H CH,C00H HCOOH
÷ +
÷ +
Traces
+ ÷
Ditto
÷ ÷ + + ÷
H~0 C~H~
C~-Is0H C~HsCH, C,H,C,H, C,H~CH(CH,), C~H,CH0 C,H~CHO
Traces
+
÷ + +
Diane
+ + + + q+ + ÷ +
+ + + + + + + + +
+ + +
+ +
* _Notation: + , product is present; --, is not present,
e n e r g y for the m o n o m o l e c u l a r reaction of t h e isomerization of a l k y l p e r o x i d e radicals is a b o u t 20 keal/mole, while t h a t for the bimolecular r e a c t i o n o f the form a t i o n of h y d r o p e r o x i d e is 10 kcal/mole [8, 10]. Simple calculations show t h a t a t 175 ° the ratio o f the reaction rates for t h e isomerization a n d for t h e f o r m a t i o n T A B L E ~. H Y D R O P E R O X I D E S
CONTENT
AND
WEIGHT
LOSS OF D I A N E UNDER DIFFE1LENT CONDITIONS
Hydroperoxides
Temperature, °C
Weight loss, %
175 200
12 18
content,
R O O H mole/ / d i a n e mole 0.17 0.12
o f h y d r o p e r o x i d e s is close to unity, while a t 300 ° this ratio a m o u n t s to several thousands, i.e. the isomerization reaction becomes practically t h e sole m e a n s o f converting the peroxyradicals. T h e isomerization of p r i m a r y alkylperoxide radicals is t h e r e f o r e m o r e p r o b a b l e t h a n the f o r m a t i o n of peroxide u n d e r the t e m p e r a t u r e conditions a d o p t e d for t h e o x i d a t i o n of p o l y e a r b o n a t e .
Intermediate products of oxidation of polyearbonate
1371
In most cases [8-10] the isomerization of alkylperoxide radicals results in the formation of various oxygen-containing products, some of which are efficient chain-branching agents. The presence of isomerization in these systems is an important stage and in some cases the determining stage as regards the overall rate and the course of oxidation. In study of the kinetic relations in the thermooxidative degradation of polycarbonate [1] it was shown that the rate of decomposition of the polymer i n v a c u o is increased if the polymer is subjected to preliminary oxidation for a short time. Besides this it was shown in [3] that high-molecular oxygen-containing decomposition products undergo further conversion, and the amount of these products in the T A B L E 3. COMPOSITION OF GASEOUS PRODUCTS OF THE THERMAL DECOMPOSITION OF POLYCARBONATE (~O) THAT HAS UNDERGOI~-E PRELIMINARY OXIDATION FOR 1 5 0 ~ N AT 300 °, AT P 0 i ~ 5 5 8 mmI-Ig
Decomposition product laco 18co 1602
leO18O 1802
16CO~ 16COX~O ISCO2 Altogether
Total amount of Amount of product of varyproduct, % ing isotopic composition, % 10 13 1.6 2-4 1-0 72
23.0 5.0 72.0 100
polymer starts to decrease with decreasing oxygen concentration. Comparison of the products formed in the degradation of polycarbonate under different conditions (Table 1) shows that aldehydes undergo further oxidation, and the amount of aldehydes when the polymer is oxidized under static conditions is much reduced compared with the amount in the products of oxidation in the oxidizing apparatus. In order to determine the structure of the intermediate oxygen-containing high-molecular products of oxidation which are responsible for the accelarated rate of thermal decomposition of the polymer i n v a c u o [1] a study was made of the gaseous products of pyrolysis of PC which had been subjected to preliminary oxidation b y oxygen enriched with isotope isO. The procedure was described in [3]. The results of the analysis of gaseous products of the thermal degradation of PC that had undergone preliminary oxidation are given in Table 3, which shows that the main decomposition products are CO and CO s . The ratio of the isotopic composition for 16CO and 18CO shows that carbon
1372
A.I. S1D~v
et
al.
monoxide is formed almost entirely as a result of the decomposition of oxygencontaining products of oxidation, and not as a result of the decay of ester bonds. At the same time isotope 1sO is not present in the carbon dioxide, which shows t h a t the latter is formed solely from ester bonds in the degradation process. This is quite understandable, taking into account t h a t no oxygen is present in the decomposition, and that CO 2 is formed solely through the further oxidation of aldehyde groups. The ratio of the isotopic composition of the oxygen formed in the decomposition of the polymer is similar to the isotopic composition of the initial oxygen. Consequently oxygen is not formed in the decay of ester groups, as in the decomposition of polycarbonate exposed to ionizing irradiation [11], when oxygen was detected in the gaseous products of degradation. The presence of insignificant amounts of oxygen under these conditions m a y be attributed to the partial recombination of tertiary alkylperoxide radicals taking place along with the formation of molecular oxygen. Thus Traylor and Bartat [12] showed clearly that in the oxidation of cumene by oxygen enriched with 1sO alkylpcroxide radicals recombine by the reaction:
J--~
--'\-/
CH3
CH 3
CHs CHs
CH3
c_~,O
I
CHs
CH~ ~O_C_J
%,+ o o
I \=/
CHa
A similar reaction appears to be possible with polycarbonate:
H3C--C--CH~06 + 60--CH2--C--CH.-~
/
\C>-
-+H3C.~C--CH~--O--O--CH2--C--CHs q- 02
In view of the above considerations we conclude therefore that at 250-300 ° the oxidation of polycarbonate starts to develop at an appreciable rate along with the formation of alkylperoxide radicals. Isomerization of the latter results in the formation of a number of intermediate low-molecular and high-molecular earbonyl type products which undergo further conversions and participate in the development of the reaction.
Intermediate products of oxidation of polycarbonate 2
3
1373
lg
///\,\
7
General arrangement of oxidizing apparatus: 1-- cylinder containing oxygen; 2 -- drying system; 3--rheometer; 4--reactor; 5--oxygen enters ~eactor; 6--traps; 7--heater with cupric oxide; 8--coiler for collecting CO2; 9 - gas buret; 10--vacuum stopcocks; //--funnel containing iced acetic acid. In the light of these data the hydroperoxide mechanism of polycarbonate oxidation proposed b y Lee [13] is improbable and unconvincing, particularly as the author includes in the scheme the isomerization of alkyl radicals which requires considerably higher activation energy than the formation of alkylperoxide radicals: l ~ - O 2 - > R O ( ) , ( E = 0 ) and could not be of any real importance in the presence of oxygen [8, 9]. CONCLUSIONS
(1) The oxidation of 2,2-di-(4-hydroxyphenyl)propane is a chain radical process which develops through hydroperoxides. The stationary concentration of the latter decreases as the oxidation temperature rises. (2) The thermooxidative degradation of polycarbonate is a chain radical process which proceeds with the formation of alkylperoxide radicals. Further isomerization of the latter results in the formation of a number of oxygen-containing carbonyl type products, which undergo further conversions during the degradation process and participate in the development of the reaction. Translated by RI J. A. HEI~DRY REFERENCES
1. B. M. KOV~_.RSIT~YA, M. S..~KUT]N, A. I. SIDNEV, 1V[. P. YAZV[KOVA and M. B. NEI-I~AN, Vysokomo]. soyed. 5: 649, 1963 2. M. S. AKUTIN, V. N. KOTRELEV, B. M. KOVARSKAYA, Ye. D. KOSTRYUKOVA, V. V. TARASOV, A. I. SIDNEV, E. RODIN, O. N. NITCHE and M. B. NEIMAN, Plast. massy 6: 26, 1963 3. A. I. SIDNEV, A. S. TELESHOVA, B. M. KOVARSKAYA and A. N. PRAVEDNIKOV, Vysokomol. soyed. 9B: 134, 1967
1374
O.V. LIP.~TOVet al.
4. A. I. SIDNEY, B. M. KOVARSKAYA and A. N. PRAVEDNIKOV, Vysokomol. soyed. 9B: 129, 1967 (Not translated in Polymer Sci. U.S.S.R.) 5. M. S. EVENTOVA, Vestn. Mosk. State Univ. "Khimiya", No. 2, 72, 1961 6. M. S. EVENTOVA, Oxygen Oxidation of Hydrocarbons in the Liquid Phase (in Russian), puhl. by AN SSSR, 1959 7. M. B. NEIMAN, B. M. KOVARSKAYA, M. P. YAZVIKOVA, A. I. 8IDNEV and M. S. AKUTIN, Vysokomol. soyed. 3: 602, 1961 (Not translated in Polymer Sci. U.S.S.R.) 8. N.N. SEMENOV, O nekotorykh problemakh khimicheskoi kinetiki i reaktionnoi sposobnosti {Problems of Chemical Kinetics and Reactivity) (in Russian). publ. by AI~ SSSR, 1958 9. A. FISH, Quart. Rev. 18: 243, 1964 10. V. B. MILLER, M. B. NEIMA~, V. S. PUDOV and L. I. LAFER, Vysokomol. soyed. 1: 696:1959 (Not translated in Polymer Sci. U.S.S.R.) 11. I. H. GOLDEN and E. A. HARELL, J. Polymer Sci. AI: 1671, 1963 12. T. G. TRAYLOR and P. D. BARTAT, Tetrahedron Letters, 24, 30, 1960 13. L. LEE, J. Polymer Sci. A2: 2859, 1964
EFFECT OF MANUFACTURING CONDITIONS ON THE STRUCTURE AND BEHAVIOUR OF POLYVINYLCHLORIDE FILMS* O. V. LIPATOV, 1~/[. B. KONSTANTII~OPOL'SKAYA, 1~. S. MONASTYRSKAYA,Z. YA. ~BERESTNEVAa n d V. A. KARGIN L. Ya. Karpov Physicochemical Institute Moscow Technological Institute for Light Industry
(Received 27 July 1967)
MA~¥ papers dealing with the relationship between mechanical properties and structure of polymers have recently shown that physical and mechanical properties are largely determined by the level of supermolecular organization [1-3]. It is well known that a morphological secondary structural film pattern is observed in polyvinylchloride (PVC) obtained by stereospecifle polymerization, which is typical of crystalline polymers [4]. Polymer chain ordering was also found in PVC of irregular structure formed by free radical polymerization. The association of PVC molecules in methylethylketone and other solvents was studied by Hengstenberg and Sehuch~[5]. They noted that the formation of associates is influenced by the solvent, the dissolving process and molecular weight. By sedimentation analysis, viscometry, electron microscopy and the low-angle X-ray method, the transverse dimensions of associates were determined. They are in the range of 70-80 A, according to low-angle X-ray method and 120-160 A, according to sedimentation and electron microscope data. In addition, in irregular PVC [6, 10] the formation of spherulites of up to * Vysokomol. soyed. A1O: No. 5, 1183-1190, 1968.