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Mechanism of the thermal decomposition of cellulose in vacuum —I. Comparative study of thermal decomposition of cotton cellulose and of cellulose hydrate
Abstracts
581
rates from 50 to 1000 ram/rain SKB and SKS-80 vuleanizates with thermal black or a small amount of channel black as well as filled N K vuloanizates have only one temperature-rate region of knotty tear. With high channel carbon content SKB and SKS-30 vuleanizates yield two knotty tear regions. I t has been suggested that one of the knotty tear regions is connected with the presence in the vhlc~nizates of the carbon black particles, where~s the other with carbon black chain structures.
MECHANISM OF THE THERMAL DE/~OM]POS]['rION OF CI~.T.UIA)$E IN VACUUM --I. COMPAEATIVE STUDY OF THERMAL DE¢OMPOSI']ffON OF ODTrON CELLULOSE AND OF CELLULOSE HYDRATE
O. P. Golova, R. G. K r y l o v a a n d N. N. N i k o l a e v a , V y ~ k o m o l . soedin. 1: No. 9, 1295--]304, 1959 IN order to elucidate the mechanism of thermal decomposition of cellulose with formation of p-1,6-anhydro-1,5, glucopyranose a comparative study of the relations governing the formation of volatile products and of the changes in properties of the cellulose itself for two of its structural modifications has been made. The experimental results indicate that decomposition of cotton cellulose proceeds in two stages. Decomposition of the first 2--4 per cent is accompanied by a sharp fall in the degree of polymerization. On decomposition of the following 70-80 per cent the degree of polymerization remains constant. When the first 10-20 per cent cellulose is decomposed the process proceeds with little levoglucosan formation and with large .yield of volatile products. I n the subsequent 50-70 per o~nt decomposition, the levoglucosan yield is practically constant. MECHANISM OF THE T I ~ R M ~ L DECOMPOSITION OF CELLULOSE --1I. ~ I T I O N OF T][~ THERMAL DECOMP08rrlON
.IN VAL'UUM
O. P. Golova, R. G. K r y l o v a a n d I. I. N i k o l a e v a , V y s o k o m o l . soedin, h 1305-1308, 1959.
No. 9,
Ttr]~ thermal decomposition of cotton cellulose in vacuum has been shown to be capable of inhibition by products of the concurrent decomposition of glucose. The active fragments of the glucose molecules do not participate in the decomposition process of the cellulose macromolecules in the initial stage. Inhibition is accompanied by change in direction of the process, products of the more far.going C--C bond cleavage being formed. MECHANICAL VITRIFICATION ~ N D THE ACTIVATION ENERGY OF RUbBER-LIKE POLYMERS
G. M. B a r t e n e v a n d V. D. Zaitseva, V y s o k o m o l . soedin. 1: No. 9, 1309-1318, 1959. Tire results of investigations of mechanical vitrification of a b r o i l variety of rubbers over the range of deformation frequencies 0.1-1000 sec -1 have been presented. Based on the mechanical model of rubber with a single relaxation time and on experimental data the energy of activation of molecular rearrangements for various rubbers has been calculated and compared with the mechanical vitrification temperature. 3~ Polymer 3
581
rates from 50 to 1000 ram/rain SKB and SKS-80 vuleanizates with thermal black or a small amount of channel black as well as filled N K vuloanizates have only one temperature-rate region of knotty tear. With high channel carbon content SKB and SKS-30 vuleanizates yield two knotty tear regions. I t has been suggested that one of the knotty tear regions is connected with the presence in the vhlc~nizates of the carbon black particles, where~s the other with carbon black chain structures.
MECHANISM OF THE THERMAL DE/~OM]POS]['rION OF CI~.T.UIA)$E IN VACUUM --I. COMPAEATIVE STUDY OF THERMAL DE¢OMPOSI']ffON OF ODTrON CELLULOSE AND OF CELLULOSE HYDRATE
O. P. Golova, R. G. K r y l o v a a n d N. N. N i k o l a e v a , V y ~ k o m o l . soedin. 1: No. 9, 1295--]304, 1959 IN order to elucidate the mechanism of thermal decomposition of cellulose with formation of p-1,6-anhydro-1,5, glucopyranose a comparative study of the relations governing the formation of volatile products and of the changes in properties of the cellulose itself for two of its structural modifications has been made. The experimental results indicate that decomposition of cotton cellulose proceeds in two stages. Decomposition of the first 2--4 per cent is accompanied by a sharp fall in the degree of polymerization. On decomposition of the following 70-80 per cent the degree of polymerization remains constant. When the first 10-20 per cent cellulose is decomposed the process proceeds with little levoglucosan formation and with large .yield of volatile products. I n the subsequent 50-70 per o~nt decomposition, the levoglucosan yield is practically constant. MECHANISM OF THE T I ~ R M ~ L DECOMPOSITION OF CELLULOSE --1I. ~ I T I O N OF T][~ THERMAL DECOMP08rrlON
.IN VAL'UUM
O. P. Golova, R. G. K r y l o v a a n d I. I. N i k o l a e v a , V y s o k o m o l . soedin, h 1305-1308, 1959.
No. 9,
Ttr]~ thermal decomposition of cotton cellulose in vacuum has been shown to be capable of inhibition by products of the concurrent decomposition of glucose. The active fragments of the glucose molecules do not participate in the decomposition process of the cellulose macromolecules in the initial stage. Inhibition is accompanied by change in direction of the process, products of the more far.going C--C bond cleavage being formed. MECHANICAL VITRIFICATION ~ N D THE ACTIVATION ENERGY OF RUbBER-LIKE POLYMERS
G. M. B a r t e n e v a n d V. D. Zaitseva, V y s o k o m o l . soedin. 1: No. 9, 1309-1318, 1959. Tire results of investigations of mechanical vitrification of a b r o i l variety of rubbers over the range of deformation frequencies 0.1-1000 sec -1 have been presented. Based on the mechanical model of rubber with a single relaxation time and on experimental data the energy of activation of molecular rearrangements for various rubbers has been calculated and compared with the mechanical vitrification temperature. 3~ Polymer 3