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1990 Volume 8 Issue 1
1990, 8(1): 1-9
Abstract:
1990, 8(1): 10-16
Abstract:
The copolymerizations of methyl acrylate (MA) with different N- arylmethacrylamide (N-ArMA) were carried out in benzene solution by free radical initiation. The compositions of the copolymers were deter mined by1H NMR method. The monomer reactivity ratios were calculated by the Fineman-Ross (F-R) method. The reactivity ratios and the activity of various N-ArMA with MA were investigated.
The copolymerizations of methyl acrylate (MA) with different N- arylmethacrylamide (N-ArMA) were carried out in benzene solution by free radical initiation. The compositions of the copolymers were deter mined by1H NMR method. The monomer reactivity ratios were calculated by the Fineman-Ross (F-R) method. The reactivity ratios and the activity of various N-ArMA with MA were investigated.
1990, 8(1): 17-24
Abstract:
The sequence structures of emulsion-processed SBR and solution-processed (by lithium catalyst) SBR were investigated by 13C-NMR spectroscopy. Seventeen peaks within unsaturated carbon region were recorded under the adopted experimental conditions. Assignments for these peaks were made by empirical-parameter-evaluation method.
The sequence structures of emulsion-processed SBR and solution-processed (by lithium catalyst) SBR were investigated by 13C-NMR spectroscopy. Seventeen peaks within unsaturated carbon region were recorded under the adopted experimental conditions. Assignments for these peaks were made by empirical-parameter-evaluation method.
1990, 8(1): 25-35
Abstract:
The study on 13C-NMR spectra of aliphatic carbon region of emuision-processed and solution-processed (by lithium catalyst) SBR was carried out. The assignments for more than thirty odd peaks observed experimentally were made by using "corresponding analysis" method, combined with the empirical parameters reported in literature. The peak intensifies were calculated based on BemouUian statistic assumption.
The study on 13C-NMR spectra of aliphatic carbon region of emuision-processed and solution-processed (by lithium catalyst) SBR was carried out. The assignments for more than thirty odd peaks observed experimentally were made by using "corresponding analysis" method, combined with the empirical parameters reported in literature. The peak intensifies were calculated based on BemouUian statistic assumption.
1990, 8(1): 36-43
Abstract:
The diphenyliodonium salt (DPIOC)/triethylamine (TEA) is used as photoinitiator for radical photopolymerization. It was found that a ground state CT complex formed between DPIOC as electron acceptor and TEA as electron donor, which results in extending the photosensitivity range of DPIOC/TEA system up to above 500nm compared with DPIOC alone. The kinetic studies on photopolymerization of methyl methacrylate (MMA) were carried out in CH_3CN: H2O (14: 1, v/v) mixture solution at 30℃ by dilatometer. The results obtained show that the polymerization rate(Rp)increases with increasing concentrations of SPIOC and TEA with exponent 0.65 and 0.62 respectively.The activation energy Ea and kp/k1/2t value were determined to be 4.1 Kcal·mol-1 and 0.045 respectively.The other influence factors and reaction mechanism were also discussed.
The diphenyliodonium salt (DPIOC)/triethylamine (TEA) is used as photoinitiator for radical photopolymerization. It was found that a ground state CT complex formed between DPIOC as electron acceptor and TEA as electron donor, which results in extending the photosensitivity range of DPIOC/TEA system up to above 500nm compared with DPIOC alone. The kinetic studies on photopolymerization of methyl methacrylate (MMA) were carried out in CH_3CN: H2O (14: 1, v/v) mixture solution at 30℃ by dilatometer. The results obtained show that the polymerization rate(Rp)increases with increasing concentrations of SPIOC and TEA with exponent 0.65 and 0.62 respectively.The activation energy Ea and kp/k1/2t value were determined to be 4.1 Kcal·mol-1 and 0.045 respectively.The other influence factors and reaction mechanism were also discussed.
1990, 8(1): 44-50
Abstract:
A novel binary photosensitization system composed of benzophenone (BP)/diphenyliodonium chloride (DPIOC) Ariethylamine (TEA), exhibiting a good photoresponse at near UV and visible light regions, was used as the initiator for photopolymerization of MMA. The radical photogeneration in the binary system consists mainly of two parallel reactions, i. e. , BP/TEA photohydrogen-abstraction and DPIOC/TEA complex photodecomposition, but the latter is more active than the former. The results of comparative study indicate that the rate of polymerization induced by the binary system (BDT) is remarkably higher than those by the corresponding single systems The polymerization rates are proportional to [BP]0.16,[DPIOC]0.32,[TEA]0.45 and [MMA].The mechanism is also discussed.
A novel binary photosensitization system composed of benzophenone (BP)/diphenyliodonium chloride (DPIOC) Ariethylamine (TEA), exhibiting a good photoresponse at near UV and visible light regions, was used as the initiator for photopolymerization of MMA. The radical photogeneration in the binary system consists mainly of two parallel reactions, i. e. , BP/TEA photohydrogen-abstraction and DPIOC/TEA complex photodecomposition, but the latter is more active than the former. The results of comparative study indicate that the rate of polymerization induced by the binary system (BDT) is remarkably higher than those by the corresponding single systems The polymerization rates are proportional to [BP]0.16,[DPIOC]0.32,[TEA]0.45 and [MMA].The mechanism is also discussed.
1990, 8(1): 51-60
Abstract:
Time resolved laser spectroscopy and GC/MS were used to investigate the primary processes and the side reactions occurring in benzophenone and chlorothioxanthone/amine systems used as photoinitiators of radical polymerization. The discrepancy observed between the experimental data and the expected behaviour is accounted for by detrimental chemical reaction involving the ketone triplet state, the ketyl radical and the amine-derived radical.
Time resolved laser spectroscopy and GC/MS were used to investigate the primary processes and the side reactions occurring in benzophenone and chlorothioxanthone/amine systems used as photoinitiators of radical polymerization. The discrepancy observed between the experimental data and the expected behaviour is accounted for by detrimental chemical reaction involving the ketone triplet state, the ketyl radical and the amine-derived radical.
1990, 8(1): 61-68
Abstract:
The density, equilibrium heat of fusion and equilibrium melting temperature of Nylon 1010 were determined by means of infrared spectrum, differential scanning calorimetry, wide angle X-ray diffraction and density measurement techniques. According to Starkweatber' s method crystalline density ρc and amorphous density ρa were estimated to be 1.098 and 1.003 g/cm3 respectively by extrapolating the straight lines of the IR absorbanee against density to zero intensity. Owing to the less intense in absorbance and less sensitive to the change in crystallinity of the amorphors band the thus obtained Pcwas too low in value.Thereby the value of the ratio Pc/Pa is far less than generally accepted mean value for most crystalline polymers.Accordingly,traditional X-ray diffraction method was used through detemining the crystalline dimension(α=4.9 .B= 5.4, C=27.8 ,α=49°β77.0°, γ=63.5°),and a rather correct value of μc or the crystal density 1.13g/cm3 was obtained.The equilibrium heat of fusion △om was estimated to be 244.0J/g plotting △Hm's of specimens with different crystallinity against their corresponding specific volumes Vspand extrapolating to completely crystalline condition (Vcsp=1/ρc As to the equilibrium melting temperature Tom,because of the easiness of recrystallization of melt crystallized Nylon 1010 specimen,the well-known Hoffman's Tm-Tc method failed in determining this value and an usually rarely used Kamide double extrapolation method was adopted.The so obtained value of Tom 487 seems to be fairly reasonable.
The density, equilibrium heat of fusion and equilibrium melting temperature of Nylon 1010 were determined by means of infrared spectrum, differential scanning calorimetry, wide angle X-ray diffraction and density measurement techniques. According to Starkweatber' s method crystalline density ρc and amorphous density ρa were estimated to be 1.098 and 1.003 g/cm3 respectively by extrapolating the straight lines of the IR absorbanee against density to zero intensity. Owing to the less intense in absorbance and less sensitive to the change in crystallinity of the amorphors band the thus obtained Pcwas too low in value.Thereby the value of the ratio Pc/Pa is far less than generally accepted mean value for most crystalline polymers.Accordingly,traditional X-ray diffraction method was used through detemining the crystalline dimension(α=4.9 .B= 5.4, C=27.8 ,α=49°β77.0°, γ=63.5°),and a rather correct value of μc or the crystal density 1.13g/cm3 was obtained.The equilibrium heat of fusion △om was estimated to be 244.0J/g plotting △Hm's of specimens with different crystallinity against their corresponding specific volumes Vspand extrapolating to completely crystalline condition (Vcsp=1/ρc As to the equilibrium melting temperature Tom,because of the easiness of recrystallization of melt crystallized Nylon 1010 specimen,the well-known Hoffman's Tm-Tc method failed in determining this value and an usually rarely used Kamide double extrapolation method was adopted.The so obtained value of Tom 487 seems to be fairly reasonable.
1990, 8(1): 69-74
Abstract:
In this paper we have presented the results of acoustic emission (AE) during non-isothemal crystallization of polypropylene (PP) melt with mean cooling rate 4℃/min, and discussed the effects of molecular weight (MW) on AE activity. It is shown that the amount of AE ring-down counts during whole crystallization of PP depends on the MW strongly.The copious AE bursts have been observed at the late stage of PPcrystallization. AE bursts are caused by cracking, crazing and cavitation between spherulites and inside spherulites.
In this paper we have presented the results of acoustic emission (AE) during non-isothemal crystallization of polypropylene (PP) melt with mean cooling rate 4℃/min, and discussed the effects of molecular weight (MW) on AE activity. It is shown that the amount of AE ring-down counts during whole crystallization of PP depends on the MW strongly.The copious AE bursts have been observed at the late stage of PPcrystallization. AE bursts are caused by cracking, crazing and cavitation between spherulites and inside spherulites.
1990, 8(1): 75-78
Abstract:
The experimental investigation on the conformation of a thermotropic main-chain nematic polymer by small-angle X-ray scattering (SAXS) has been carried out. The average radius of gyration of the polymer has been determined in nematic and isotropic state respectively. The experiment shows that the boundary between domains is not sharp but diffuse, and the diffuse-boundary thickness of the polymer as a function of temperature has been given.
The experimental investigation on the conformation of a thermotropic main-chain nematic polymer by small-angle X-ray scattering (SAXS) has been carried out. The average radius of gyration of the polymer has been determined in nematic and isotropic state respectively. The experiment shows that the boundary between domains is not sharp but diffuse, and the diffuse-boundary thickness of the polymer as a function of temperature has been given.
1990, 8(1): 79-86
Abstract:
Three polycaprolactam samples modified by 0.05—0.50% polybenzimidazole (PBI) by weight were prepared. Their structure and mechanical properties were characterized by means of FT-IR, SEM, DTA, density tensile, impact and viscoelastic method. PBI delayed the superimposed polymerization-crystallization process of the activated anionic polymerization of caprolactam. The monomer casting (MC) nylons modified by PBI had lower crystallinities, lower Tg and more nearly perfect spherulites than MC nylon itself, and more nearly perfect spherulites than MC nylon itself,and showed a typical toughening effect.
Three polycaprolactam samples modified by 0.05—0.50% polybenzimidazole (PBI) by weight were prepared. Their structure and mechanical properties were characterized by means of FT-IR, SEM, DTA, density tensile, impact and viscoelastic method. PBI delayed the superimposed polymerization-crystallization process of the activated anionic polymerization of caprolactam. The monomer casting (MC) nylons modified by PBI had lower crystallinities, lower Tg and more nearly perfect spherulites than MC nylon itself, and more nearly perfect spherulites than MC nylon itself,and showed a typical toughening effect.
1990, 8(1): 87-92
Abstract:
Three polycaprolactam samples modified by 0.05—0.50% polyphenylquinoxaline(PPQ)by weight were prepared.Their structure and mechanical properties were characterized by FT-IR, SEM, density, tensile, impact, DTAand visco-elastic method, PPQ induced the formation of "crystal grains" distributed evenly over nylon spherulites in modified samples, which were observed for the first time, and strengthened modified samples. Modified nylons had higher crystallinities, higher Tg, more nearly perfect spherulites than MC nylon itself,and showed typical reinforcing effect on mechanical properties.
Three polycaprolactam samples modified by 0.05—0.50% polyphenylquinoxaline(PPQ)by weight were prepared.Their structure and mechanical properties were characterized by FT-IR, SEM, density, tensile, impact, DTAand visco-elastic method, PPQ induced the formation of "crystal grains" distributed evenly over nylon spherulites in modified samples, which were observed for the first time, and strengthened modified samples. Modified nylons had higher crystallinities, higher Tg, more nearly perfect spherulites than MC nylon itself,and showed typical reinforcing effect on mechanical properties.
1990, 8(1): 93-96
Abstract:
Crosslinked poly(methyl methacrylate) and polystyrene with barium dimethacrylate [Ba(MA)2] as crosslinking agent have been synthesized. The relationship between X-ray absorbability and the content of Ba(MA)2 in polymers was investigated. TGA and DSC results indicated that the crosslinked polymers containing barium dimethacrylate have a much better heat stability than pure PMMA or PS. The mechanical properties of the polymers containing barium are improved in comparison with the pure PMMA.
Crosslinked poly(methyl methacrylate) and polystyrene with barium dimethacrylate [Ba(MA)2] as crosslinking agent have been synthesized. The relationship between X-ray absorbability and the content of Ba(MA)2 in polymers was investigated. TGA and DSC results indicated that the crosslinked polymers containing barium dimethacrylate have a much better heat stability than pure PMMA or PS. The mechanical properties of the polymers containing barium are improved in comparison with the pure PMMA.
