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1985 Volume 3 Issue 1
1985, 3(1): 1-10
Abstract:
Two new types of block polyurethane elastomers were prepared using two polyols polyethyleneadipate and PTHF respectively, and diisocyanate MDI extended with Dianol-33 (a new extender),by one step reaction and casting method. The properties of these polyurethane were studied by employing Instron infrared spectroscopy,DSC and wide angle X-ray diffraction etc.
Two new types of block polyurethane elastomers were prepared using two polyols polyethyleneadipate and PTHF respectively, and diisocyanate MDI extended with Dianol-33 (a new extender),by one step reaction and casting method. The properties of these polyurethane were studied by employing Instron infrared spectroscopy,DSC and wide angle X-ray diffraction etc.
1985, 3(1): 11-16
Abstract:
Radiation-induced emulsion polymerization of styrene in soap-free system has beenstudied and the monodisperse polystyrene lattices were obtained. Both its purity and emulsionconversion are better than that of chemically initiated polymers.
Radiation-induced emulsion polymerization of styrene in soap-free system has beenstudied and the monodisperse polystyrene lattices were obtained. Both its purity and emulsionconversion are better than that of chemically initiated polymers.
1985, 3(1): 17-25
Abstract:
The structure effects of polymers on the relationship between sol fraction and radiation dose arediscussed in detail. In consideration of the deviation of experimental results from Charlesby-Pin-ner's and Chen-Liu-Tang's expressions relating sol fraction to radiation dose, we introduced an ex-ponent β concerned with the structure and property parameters of a polymer (glass transition tem-perature Tg and molecular internal rotating steric factor δ) and assumed that the fracture density isproportional to Rβ(R is radiation dose).Thus,a general expression,formula (9),relating sol fraction to radiation dose is derived.When β=1 and β=0.5,this expression is reduced to the abpve-said two expressions,Using this general expression,the experimental data of a number of polymers are treated.It is shown that the expression is in good agreement with the experimental results,β value is in the range of 0.5 to 1.0.
The structure effects of polymers on the relationship between sol fraction and radiation dose arediscussed in detail. In consideration of the deviation of experimental results from Charlesby-Pin-ner's and Chen-Liu-Tang's expressions relating sol fraction to radiation dose, we introduced an ex-ponent β concerned with the structure and property parameters of a polymer (glass transition tem-perature Tg and molecular internal rotating steric factor δ) and assumed that the fracture density isproportional to Rβ(R is radiation dose).Thus,a general expression,formula (9),relating sol fraction to radiation dose is derived.When β=1 and β=0.5,this expression is reduced to the abpve-said two expressions,Using this general expression,the experimental data of a number of polymers are treated.It is shown that the expression is in good agreement with the experimental results,β value is in the range of 0.5 to 1.0.
KINETIC STUDY OF GAS-PHASE POLYMERIZATION OF PROPENE BY THE INHIBITION METHOD USING CARBON MONOXIDE*
1985, 3(1): 26-34
Abstract:
The inhibition method using CO to determine the active center concentration C* in olefin poly-merization and the kinetics of gas-phase polymerization of propene were studied. The reliabilityof the method when used in gas-phase polymerization of propene is proved and the influencing fac-tor of the method is found to be the "repeating inhibition" of CO to the active centers. The C*, the rate constant kP and the activation energy were determined from the experimentalresults. We concluded that the C* decreases with polymerization time and coincides with the decay rate of the polymerization.
The inhibition method using CO to determine the active center concentration C* in olefin poly-merization and the kinetics of gas-phase polymerization of propene were studied. The reliabilityof the method when used in gas-phase polymerization of propene is proved and the influencing fac-tor of the method is found to be the "repeating inhibition" of CO to the active centers. The C*, the rate constant kP and the activation energy were determined from the experimentalresults. We concluded that the C* decreases with polymerization time and coincides with the decay rate of the polymerization.
1985, 3(1): 35-41
Abstract:
In the stress relaxation process of HEPP (Hard Elastic Polypropylene) fibre, the added liquids,e. g. ethanol and n-hexane, which can wet polypropylene, cause an abrupt decrease of stress. By measuring the contact angles and decreases of stress and evaluating according to Young-Dupre's equation, it was found that about one-third of the initial stress is associated with the sur-face energy. When soaked in liquids mentioned above, HEPP fibre almost lost its elasticity. It isnot the result of plasticizing or 'solvent cracking'but most likely comes from the changes of the surface energy.
In the stress relaxation process of HEPP (Hard Elastic Polypropylene) fibre, the added liquids,e. g. ethanol and n-hexane, which can wet polypropylene, cause an abrupt decrease of stress. By measuring the contact angles and decreases of stress and evaluating according to Young-Dupre's equation, it was found that about one-third of the initial stress is associated with the sur-face energy. When soaked in liquids mentioned above, HEPP fibre almost lost its elasticity. It isnot the result of plasticizing or 'solvent cracking'but most likely comes from the changes of the surface energy.
1985, 3(1): 42-47
Abstract:
Two new routes to polyamides and polyesters were established, based on the polycondensationof new typical active diacylamide of benzotriazole, such as 1, 1'-(isophthaloyl) bisbenzotriazole(IPBBT) and 1, 1'-(terephthaloyl)bisbenzotriazole (PBBT) with diamines, diols and diphenol underdifferent mild conditions. The N-acylation of polycondensation occurred at room temperaturewithout added catalyst, the O-acylation of polycondensation had to complete in the presence oftriethylamine as a catalyst at 60℃.
Two new routes to polyamides and polyesters were established, based on the polycondensationof new typical active diacylamide of benzotriazole, such as 1, 1'-(isophthaloyl) bisbenzotriazole(IPBBT) and 1, 1'-(terephthaloyl)bisbenzotriazole (PBBT) with diamines, diols and diphenol underdifferent mild conditions. The N-acylation of polycondensation occurred at room temperaturewithout added catalyst, the O-acylation of polycondensation had to complete in the presence oftriethylamine as a catalyst at 60℃.
1985, 3(1): 48-55
Abstract:
Polystyrylphosphine-Pd(0) and silica supported polysiloxane-phosphine-Pd(0) complexeswere synthesized and characterized. Their catalytic properties for the decarboxylation of allyl β-keto esters were investigated. It was found that these complexes have good catalytic activities undermild condition for this decarboxylation in which many novel unsaturated ketones were obtained.The selectivity of this catalytic decarboxylation depends on the polymer ligand and the P/Pd ratioof catalyst. The stabilities of polymer phosphine-Pd(0) complexes catalysts are better than their homogeneous analogue.
Polystyrylphosphine-Pd(0) and silica supported polysiloxane-phosphine-Pd(0) complexeswere synthesized and characterized. Their catalytic properties for the decarboxylation of allyl β-keto esters were investigated. It was found that these complexes have good catalytic activities undermild condition for this decarboxylation in which many novel unsaturated ketones were obtained.The selectivity of this catalytic decarboxylation depends on the polymer ligand and the P/Pd ratioof catalyst. The stabilities of polymer phosphine-Pd(0) complexes catalysts are better than their homogeneous analogue.
1985, 3(1): 56-62
Abstract:
Structural change in an unoriented, amorphous PET film annealed at temperatures below Tgand the effect of excess enthalpy relaxation on permeation rates of CO2 gas and toluene liquid intreated samples have been studied. The results suggest that the amount of excess enthalpy relaxa-tion as determined from the endothermic peak in Tg interval, the Tg and density all increase withannealing time, but the trans-conformation component of samples decreases. No change of struc-ture in the amorphous phase was found other than the normal densification of the molecular chain packing or a reduction in free volume had occurred during the annealing regimes.Therefore,the permeation rate of CO2 gas in treated samples reduced.While the apparent permeation rate of tokuene liquid increased with annealing time because of a creation of extensive cracks at film surface arising from both the increase in embrittlement of polymer and the swelling action of toluene liquid on treated samples.
Structural change in an unoriented, amorphous PET film annealed at temperatures below Tgand the effect of excess enthalpy relaxation on permeation rates of CO2 gas and toluene liquid intreated samples have been studied. The results suggest that the amount of excess enthalpy relaxa-tion as determined from the endothermic peak in Tg interval, the Tg and density all increase withannealing time, but the trans-conformation component of samples decreases. No change of struc-ture in the amorphous phase was found other than the normal densification of the molecular chain packing or a reduction in free volume had occurred during the annealing regimes.Therefore,the permeation rate of CO2 gas in treated samples reduced.While the apparent permeation rate of tokuene liquid increased with annealing time because of a creation of extensive cracks at film surface arising from both the increase in embrittlement of polymer and the swelling action of toluene liquid on treated samples.
1985, 3(1): 63-67
Abstract:
The GPC technique with two detectors has been used to study the heterogeneity in compositionthard segment content) of a series of polyethylene terephthalate/polycaprolactone segmented copoly-mers. Improvement in data treatment has been made to avoid the difficulty resulted from the lake of low molecular weight hard segment homopolymers. Results show that for each sample the moleculesof larger coil size in CHCI3 usually have higher hard segment content. A parameter, the average deviation of hard segment content,has been proposed to characterize the heterogeneity in composition of the samples.It is found that the heterogeneity of the samples increases with increasing their average hard segment content.
The GPC technique with two detectors has been used to study the heterogeneity in compositionthard segment content) of a series of polyethylene terephthalate/polycaprolactone segmented copoly-mers. Improvement in data treatment has been made to avoid the difficulty resulted from the lake of low molecular weight hard segment homopolymers. Results show that for each sample the moleculesof larger coil size in CHCI3 usually have higher hard segment content. A parameter, the average deviation of hard segment content,has been proposed to characterize the heterogeneity in composition of the samples.It is found that the heterogeneity of the samples increases with increasing their average hard segment content.
1985, 3(1): 68-75
Abstract:
Polybutadiene (PB) was chlorinated with t-BuOCl without chain crosslinking and degradation togive chlorinated polybutadiene (Cl--PB) with active allylic chlorine atoms on the backbone. Comb-shaped PB was prepared by coupling of Cl--PB with "living" PB anions in a mixed solvent of cyc-lohexane and tetrahydrofuran. Characterization by GPC and osmometry showed that purifiedproducts were welldefined comb-shaped PB composed of low polydispersity backbone chain andrandomly distributed grafts of uniform length. Thaverage number of branches could be varied in a wide range to meet the needs of structure-properties relationship studies.
Polybutadiene (PB) was chlorinated with t-BuOCl without chain crosslinking and degradation togive chlorinated polybutadiene (Cl--PB) with active allylic chlorine atoms on the backbone. Comb-shaped PB was prepared by coupling of Cl--PB with "living" PB anions in a mixed solvent of cyc-lohexane and tetrahydrofuran. Characterization by GPC and osmometry showed that purifiedproducts were welldefined comb-shaped PB composed of low polydispersity backbone chain andrandomly distributed grafts of uniform length. Thaverage number of branches could be varied in a wide range to meet the needs of structure-properties relationship studies.
1985, 3(1): 76-81
Abstract:
Radical polperization of methyl methacrylate (MMA) initiated with organic peroxide-ditertiary amine binary systems was studied. Benzoyl peroxide (BPO), lauroyl peroxide (LPO), t-butyl hydro-peroxide (TBH), and t-butyl peroxybenzoate (TBPB) were used as organic peroxide components,aromatic ditertiay amine 4, 4′-tetramethyldiaminodiphenylmethane (TMDAPM) an d aliphatic di-tertiary amine tetramethylethylenediamine (TMEDA) were used as amine components. The polymeri-zation rate RP, the overall activation energy of polymerization Ea,the rate equation of MMA polymerization,and the end group of polymer formed were determined.
Radical polperization of methyl methacrylate (MMA) initiated with organic peroxide-ditertiary amine binary systems was studied. Benzoyl peroxide (BPO), lauroyl peroxide (LPO), t-butyl hydro-peroxide (TBH), and t-butyl peroxybenzoate (TBPB) were used as organic peroxide components,aromatic ditertiay amine 4, 4′-tetramethyldiaminodiphenylmethane (TMDAPM) an d aliphatic di-tertiary amine tetramethylethylenediamine (TMEDA) were used as amine components. The polymeri-zation rate RP, the overall activation energy of polymerization Ea,the rate equation of MMA polymerization,and the end group of polymer formed were determined.
1985, 3(1): 82-84
Abstract:
Two new polyphenylquinoxaline-platinum and rhodium complexes were synthesized and iden-tified by X-ray photoelectron spectroscopy. Their catalytic properties on hydrosilylation and hy-drogenation of olefines have been investigated. It was found that these polymer complexes possessedhigh selective catalytic activities, and were easily recoverable after each reaction and could berepeatedly used for more than 10 times while maintaining the same effectiveness.
Two new polyphenylquinoxaline-platinum and rhodium complexes were synthesized and iden-tified by X-ray photoelectron spectroscopy. Their catalytic properties on hydrosilylation and hy-drogenation of olefines have been investigated. It was found that these polymer complexes possessedhigh selective catalytic activities, and were easily recoverable after each reaction and could berepeatedly used for more than 10 times while maintaining the same effectiveness.
1985, 3(1): 85-88
Abstract:
The copolymers of 1-(acetylsalicylyloxy)ethyl methacrylate (HEMA-ASA) with methacrylicacid (MA) have been prepared and their hydrolysis in dioxane-H_2.O either in acdic or alkaline medium,at 60℃ or 37℃ have been investigated. It is found that the chief product of hydrolysis is alwaysaspirin with minor amount of salicylic acid. Due to its neighbouring group effect, the hydrolysisrate of (HEMA-ASA)-MA copolymer markedly depends on its composition and the pH value ofhydrolysis medium, i.e. the hydrolysis rate increases with increasing mole fraction of MA in the copolymer and pH value of hydrolysis medium.
The copolymers of 1-(acetylsalicylyloxy)ethyl methacrylate (HEMA-ASA) with methacrylicacid (MA) have been prepared and their hydrolysis in dioxane-H_2.O either in acdic or alkaline medium,at 60℃ or 37℃ have been investigated. It is found that the chief product of hydrolysis is alwaysaspirin with minor amount of salicylic acid. Due to its neighbouring group effect, the hydrolysisrate of (HEMA-ASA)-MA copolymer markedly depends on its composition and the pH value ofhydrolysis medium, i.e. the hydrolysis rate increases with increasing mole fraction of MA in the copolymer and pH value of hydrolysis medium.
