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1964 Volume 6 Issue 4
1964, 6(4): 269-278
Abstract:
1964, 6(4): 279-289
Abstract:
1．On the basis of the mechanism of degenerate chain—branching reaction in the pro-cess of autoxidation of olefine，and taking account of the fact that(a)decomposition of hydroperoxide would produce either free radicals or stable products，and(b)as a charac-teristic of polymer reaction in solid state chain termination could take place by uniradical reaction，the present authors derived the following equation describing the kinetics of oxygen—absorption by the polymer at a given temperature： 1n Vt/Vco-1-Vt/Vco=(ak3No-yk5)t+C where a=xk7——xk7+(1-x)k8 X and y一the fractions of chainbranching reaction and uniradical termination respectively；Vt-the volume of oxygen absorbed by the polymer at time t(cc 02／g polymer)；Voo一the limiting volume of oxygen absorbed by the polymer during the whole process (cc O2／g polymer)；K7 and k．s--rate constants for decomposition of hydroperoxide into free radicals and stable products respectively；
1．On the basis of the mechanism of degenerate chain—branching reaction in the pro-cess of autoxidation of olefine，and taking account of the fact that(a)decomposition of hydroperoxide would produce either free radicals or stable products，and(b)as a charac-teristic of polymer reaction in solid state chain termination could take place by uniradical reaction，the present authors derived the following equation describing the kinetics of oxygen—absorption by the polymer at a given temperature： 1n Vt/Vco-1-Vt/Vco=(ak3No-yk5)t+C where a=xk7——xk7+(1-x)k8 X and y一the fractions of chainbranching reaction and uniradical termination respectively；Vt-the volume of oxygen absorbed by the polymer at time t(cc 02／g polymer)；Voo一the limiting volume of oxygen absorbed by the polymer during the whole process (cc O2／g polymer)；K7 and k．s--rate constants for decomposition of hydroperoxide into free radicals and stable products respectively；
1964, 6(4): 290-295
Abstract:
1964, 6(4): 296-303
Abstract:
The catalytic effect of 15 metallic compounds on the transesterification reaction be-tween bisphenol-A and diphenyl carbonate has been investigated，among which <>COONa，LiH，LiAc,CoAc2 and CdAc2 were found to be most active．The rate of transesterification was followed by the amount of phenol Iiberated in a definite interval of time． Experimental data showed that the reaction iS of first order with respect to bisphenol and catalyst(LiAc)but independent of the concentration of diphenyl carbonate． Activation energy were found to be 18 kcal／mole．The rate of poIycondensation with similar catalyst was determined by vaccum re-moval of diphenyl carbonate at 280℃ and estimation of the degree of polymerization by viscosity determination at 20℃． Based on the data obtained a conclusion was drawn that the polycondensation iS also a first order reaction．
The catalytic effect of 15 metallic compounds on the transesterification reaction be-tween bisphenol-A and diphenyl carbonate has been investigated，among which <>COONa，LiH，LiAc,CoAc2 and CdAc2 were found to be most active．The rate of transesterification was followed by the amount of phenol Iiberated in a definite interval of time． Experimental data showed that the reaction iS of first order with respect to bisphenol and catalyst(LiAc)but independent of the concentration of diphenyl carbonate． Activation energy were found to be 18 kcal／mole．The rate of poIycondensation with similar catalyst was determined by vaccum re-moval of diphenyl carbonate at 280℃ and estimation of the degree of polymerization by viscosity determination at 20℃． Based on the data obtained a conclusion was drawn that the polycondensation iS also a first order reaction．
1964, 6(4): 304-311
Abstract:
1964, 6(4): 312-316
Abstract:
Kinetics of polymerization of butadiene by ethyllithium in benzene have been studied by means of dihtometer． It has been shown that the polymerization rate iS first order in monomer concentration and 1／6 th order in ethyllithium concentration，when the con-centration of ethyllithium is in the range of 0．0045—0．0215 mole／liter． within 10-30℃，the activation energy of polymerization has been determined to be 19+0.5 kcal/mole．The rate of initiation has been determined by measuring the volume of ethane evolved after hydrolyzing the ethyllithium unconsumed in polymerization．The results show that when the conversion reaches about 10％，90％of ethyllithium is consumed in initiation Molecular weight distribution of the product as determined by fractional precipitation is shown to be very narrow． Addition of small quantity of tetrahydrofuran greatly increases both the polymerization rate and the initiation rate． Ethyl ether or triethylamine likewise increases the polymerization rate but less strongly．Anisole．diethyl sulfide or naphthalene almost show no effect on the polymerization rate．
Kinetics of polymerization of butadiene by ethyllithium in benzene have been studied by means of dihtometer． It has been shown that the polymerization rate iS first order in monomer concentration and 1／6 th order in ethyllithium concentration，when the con-centration of ethyllithium is in the range of 0．0045—0．0215 mole／liter． within 10-30℃，the activation energy of polymerization has been determined to be 19+0.5 kcal/mole．The rate of initiation has been determined by measuring the volume of ethane evolved after hydrolyzing the ethyllithium unconsumed in polymerization．The results show that when the conversion reaches about 10％，90％of ethyllithium is consumed in initiation Molecular weight distribution of the product as determined by fractional precipitation is shown to be very narrow． Addition of small quantity of tetrahydrofuran greatly increases both the polymerization rate and the initiation rate． Ethyl ether or triethylamine likewise increases the polymerization rate but less strongly．Anisole．diethyl sulfide or naphthalene almost show no effect on the polymerization rate．
1964, 6(4): 317-321
Abstract:
Dicyclopentadiene dioxide was hardly cured by amines or acid anhydrides alone, but can be well cured by acid anhydrides mixed with alcohols. The curing process using different amounts of maleic anhydride and glycerol were studied, and the influence on gel time and temperature-deformation curve were determined. Although dicyclopenta-diene dioxide is a diepoxide compound, the cured resin formed a more rigid molecular chain, therefore a plastic which shows no glass transition point before the decomposition temperature (ca. 300°)may be obtained under optimum amount of curing agent and proper curing conditions.
Dicyclopentadiene dioxide was hardly cured by amines or acid anhydrides alone, but can be well cured by acid anhydrides mixed with alcohols. The curing process using different amounts of maleic anhydride and glycerol were studied, and the influence on gel time and temperature-deformation curve were determined. Although dicyclopenta-diene dioxide is a diepoxide compound, the cured resin formed a more rigid molecular chain, therefore a plastic which shows no glass transition point before the decomposition temperature (ca. 300°)may be obtained under optimum amount of curing agent and proper curing conditions.
1964, 6(4): 322-329
Abstract:
(1) The relative reactivities of various methylphenysiloxanes were studied by the method of equilibration of Kantor using (CH3)4NoH as catalyst．The results are given in Fig．1—5．The reactivities of the cyclic polyphenylsiloxanes and cyclic polymethy-siloxanes were compared by means of copolymerization in the presence of (CH3)4NOH or H2SO4．See Table 1． From these results，methyl and phenyl siloxanes can be arranged in the following order of decreasing reactivity： In basic medium，[(CH3)(C6H5)ao]3>[(CH3)2slo]3>[(CH3)(C6H5)2Si]2O>[CH3)(C6H5)SiO]4>[(CH3)2SiO]4In acid medium， [(CH3)2SiO]3>[(CH3)(C6H5)SiO]3,[(CH3)2SiO]4>[(CH3)(C6H5)SiO]4,[(CH3)2SiO]4>[(CH3)(C6H5)2Si]2O．Increasing phenyl groups increases the reactivity of siloxanes in basic medium with the exception that [(C6H5)3Si]2O being less reactive than [(CH3)(C6H5)2Si]2O．This is prob-ably due to the steric hindrance of the large number of bulky phenyl groups．On the other hand，phenyl group lowers the reactivity of siloxanes in acid medium．(2) Cyclic low polymers of polysiloxane containing small amount of trifunctional groups were prepared by cohydrolysis of (CH3)2SiCl2 and CH3SiCl3．When incor-porated with [(CH3)3SiOSi(CH3)2]2O and equilibrated in the presence of (CH3)4 NOH，the equilibrium was reached only after long time of heating，and there was a lowering of the viscosity below that of the equilibrium level (Fig．6，curve 1)．This phenomenon is traced to the presence of OH groups in the cyclic low polymers． Gel formation which is observed when [(CH3)3SiOSi(CH3)2]2O is used in small amount as chain terminating agent can be avoided when [(CH3)(C6H5)2Si]2O is used in its place(Fig．6，7)．
(1) The relative reactivities of various methylphenysiloxanes were studied by the method of equilibration of Kantor using (CH3)4NoH as catalyst．The results are given in Fig．1—5．The reactivities of the cyclic polyphenylsiloxanes and cyclic polymethy-siloxanes were compared by means of copolymerization in the presence of (CH3)4NOH or H2SO4．See Table 1． From these results，methyl and phenyl siloxanes can be arranged in the following order of decreasing reactivity： In basic medium，[(CH3)(C6H5)ao]3>[(CH3)2slo]3>[(CH3)(C6H5)2Si]2O>[CH3)(C6H5)SiO]4>[(CH3)2SiO]4In acid medium， [(CH3)2SiO]3>[(CH3)(C6H5)SiO]3,[(CH3)2SiO]4>[(CH3)(C6H5)SiO]4,[(CH3)2SiO]4>[(CH3)(C6H5)2Si]2O．Increasing phenyl groups increases the reactivity of siloxanes in basic medium with the exception that [(C6H5)3Si]2O being less reactive than [(CH3)(C6H5)2Si]2O．This is prob-ably due to the steric hindrance of the large number of bulky phenyl groups．On the other hand，phenyl group lowers the reactivity of siloxanes in acid medium．(2) Cyclic low polymers of polysiloxane containing small amount of trifunctional groups were prepared by cohydrolysis of (CH3)2SiCl2 and CH3SiCl3．When incor-porated with [(CH3)3SiOSi(CH3)2]2O and equilibrated in the presence of (CH3)4 NOH，the equilibrium was reached only after long time of heating，and there was a lowering of the viscosity below that of the equilibrium level (Fig．6，curve 1)．This phenomenon is traced to the presence of OH groups in the cyclic low polymers． Gel formation which is observed when [(CH3)3SiOSi(CH3)2]2O is used in small amount as chain terminating agent can be avoided when [(CH3)(C6H5)2Si]2O is used in its place(Fig．6，7)．
1964, 6(4): 330-331
Abstract:
Polymerization of acrylonitrile by using zinc chloride as catalyst and preparation of polynitriles in the presence of metallic oxides have not been reported. In the present work polymerization of acrylonitrile in the presence of zinc chloride and several metallic oxides (ZnO, Al2O3, CuO, TiO2 etc.) has been studied.The infrared spectrum of the polymers showed a distinctive absorption of conjugated (C=N)n bond at 1600 cm-1 and the absorption of -C ≡ N at 2240 cm-1 has almost disappeared.The polymer is proved to be semiconductive.
Polymerization of acrylonitrile by using zinc chloride as catalyst and preparation of polynitriles in the presence of metallic oxides have not been reported. In the present work polymerization of acrylonitrile in the presence of zinc chloride and several metallic oxides (ZnO, Al2O3, CuO, TiO2 etc.) has been studied.The infrared spectrum of the polymers showed a distinctive absorption of conjugated (C=N)n bond at 1600 cm-1 and the absorption of -C ≡ N at 2240 cm-1 has almost disappeared.The polymer is proved to be semiconductive.
