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1988 Volume 6 Issue 2
1988, 6(2): 97-116
Abstract:
For the mechanism of isothermal bulk crystallization of high polymers, beside the nucleation and growth steps, the unimpingement of growing crystal aggregates should be taken into account for the modification of the Avrami equation. Starting from Poisson distribution function of growing crystal aggregates, the probability of the unimpinging ones should be P(0)+P(1), then the Q-modified Avrami equation thus derived can be expressed as Q(V0)=Ln[1-Ln(1-V0])+(?)-1.3179=K(?)where V0 represents the volume fraction of crystal aggregates at crystallization time t at a given temperature,while the exponent n on t relates to the mode of nucleation and growth,and Kq is the corresponding shape factor.This Q-modified one is verified satisfactory by the isothermal bulk crystallization of lanthanide catalytically polymerized polybutadiene(Ln-PB),polyisoprene(Ln-PIR) and their copolymers(Ln-PB/IR).Furthermore,the proposed mechanism is well identified by the change of morphological state during the course of crystallization of the corresponding cast film of Ln-PB/TR(92/8) at-60°(Fig.1).Upon examination of the influence of the number of entanglement on crystallization rate,it reveals the existence of two stages of entanglementation,the primary and the econdary ones(Fig.19) The equation for dependence of molecular weight and entanglement on bulk crystallization rate has been derived as Eq.13 or 18 for Ln-PB,and verified by the experimental rate date of well fractionated Ln-PB samples crystallized at-9.1 to -15℃(Fig.20).
For the mechanism of isothermal bulk crystallization of high polymers, beside the nucleation and growth steps, the unimpingement of growing crystal aggregates should be taken into account for the modification of the Avrami equation. Starting from Poisson distribution function of growing crystal aggregates, the probability of the unimpinging ones should be P(0)+P(1), then the Q-modified Avrami equation thus derived can be expressed as Q(V0)=Ln[1-Ln(1-V0])+(?)-1.3179=K(?)where V0 represents the volume fraction of crystal aggregates at crystallization time t at a given temperature,while the exponent n on t relates to the mode of nucleation and growth,and Kq is the corresponding shape factor.This Q-modified one is verified satisfactory by the isothermal bulk crystallization of lanthanide catalytically polymerized polybutadiene(Ln-PB),polyisoprene(Ln-PIR) and their copolymers(Ln-PB/IR).Furthermore,the proposed mechanism is well identified by the change of morphological state during the course of crystallization of the corresponding cast film of Ln-PB/TR(92/8) at-60°(Fig.1).Upon examination of the influence of the number of entanglement on crystallization rate,it reveals the existence of two stages of entanglementation,the primary and the econdary ones(Fig.19) The equation for dependence of molecular weight and entanglement on bulk crystallization rate has been derived as Eq.13 or 18 for Ln-PB,and verified by the experimental rate date of well fractionated Ln-PB samples crystallized at-9.1 to -15℃(Fig.20).
1988, 6(2): 117-122
Abstract:
The structure and switching properties of liquid crystalline side chain copolymers of cholesteric ester of 1,2-hydroxypropyl 2,4-di-isocyanatoluene methylmethacrylate (PHCPM) have been studied in detail. The cholesteric mesophase of PHCPM is shown by polarizing microscopy, X-ray diffraction and selective light reflection. Solution of PHCPM in CHCl3 is optically anisotropic; its optical properties were determined by specific rotation [α], circular dichroism (CD) and wide-angle hght scattering (WALS) methods.
The structure and switching properties of liquid crystalline side chain copolymers of cholesteric ester of 1,2-hydroxypropyl 2,4-di-isocyanatoluene methylmethacrylate (PHCPM) have been studied in detail. The cholesteric mesophase of PHCPM is shown by polarizing microscopy, X-ray diffraction and selective light reflection. Solution of PHCPM in CHCl3 is optically anisotropic; its optical properties were determined by specific rotation [α], circular dichroism (CD) and wide-angle hght scattering (WALS) methods.
1988, 6(2): 123-128
Abstract:
A series of copolyesters based on terephthaloyl chloride, hexamethylene glycol and hydroquinone or chlorohydroquinone were prepared. The copolymers showed composition-dependent liquid crystalline properties as verified by visual observation of stir-opalescence, polarizing microscope and DSC. The copolyesters with aromatic diol contents over a certain extent (x≥0.2) were thermotropic with wide liquid crystalline temperature ranges. Comparing with the copolyesters based on butylene glycol or ethylene glycol, the minimum fraction of aromatic diol(x value) used to get the liquid crystallinity for all these copolyesters is around 0.2 regardless of the chain lengths of aliphatic glycols.1-NMP studies revealed that copolyesters have microstructure of block sequence distribution and the mesogenic segments shorter than triad with three phenyl nuclei will not provide the liquid crystallinity.
A series of copolyesters based on terephthaloyl chloride, hexamethylene glycol and hydroquinone or chlorohydroquinone were prepared. The copolymers showed composition-dependent liquid crystalline properties as verified by visual observation of stir-opalescence, polarizing microscope and DSC. The copolyesters with aromatic diol contents over a certain extent (x≥0.2) were thermotropic with wide liquid crystalline temperature ranges. Comparing with the copolyesters based on butylene glycol or ethylene glycol, the minimum fraction of aromatic diol(x value) used to get the liquid crystallinity for all these copolyesters is around 0.2 regardless of the chain lengths of aliphatic glycols.1-NMP studies revealed that copolyesters have microstructure of block sequence distribution and the mesogenic segments shorter than triad with three phenyl nuclei will not provide the liquid crystallinity.
1988, 6(2): 129-134
Abstract:
The graft copolymerization of acrylamide onto polypropylene (PP) Film was carried out by using a capacitively coupled rf plasma apparatus with external plate electrodes. The relationship between the surface structure of the Ar plasma-treated PP films and the extent of grafting of acrylamide on the films was studied through observing the effects of discharge power and exposure time on the relative content of free-radical on the film surface. Meanwhile, the wettability and surface energy of the PP film were measured.
The graft copolymerization of acrylamide onto polypropylene (PP) Film was carried out by using a capacitively coupled rf plasma apparatus with external plate electrodes. The relationship between the surface structure of the Ar plasma-treated PP films and the extent of grafting of acrylamide on the films was studied through observing the effects of discharge power and exposure time on the relative content of free-radical on the film surface. Meanwhile, the wettability and surface energy of the PP film were measured.
1988, 6(2): 135-145
Abstract:
Four kinds of AliBu2OB' with different R' were synthesized. The effect of AliBu2OR'/AliBu3 mole ratio on the conversion, the [η] of copolymer and catalytic efficiency were studied. The conversion was increased obviously and the catalytic efficiency was 2.7 times higher than before. The effect of the amount of AliBu2OR' on the valence state of vanadium ion and the change of the valence state of vanadium ion with reaction temperature and time were studied. The VIS and IR spectra of the trinary-component catalyst system were measured.The model of active center including AliBu2OR' was proposed.The function of AliBu2OR was explained.
Four kinds of AliBu2OB' with different R' were synthesized. The effect of AliBu2OR'/AliBu3 mole ratio on the conversion, the [η] of copolymer and catalytic efficiency were studied. The conversion was increased obviously and the catalytic efficiency was 2.7 times higher than before. The effect of the amount of AliBu2OR' on the valence state of vanadium ion and the change of the valence state of vanadium ion with reaction temperature and time were studied. The VIS and IR spectra of the trinary-component catalyst system were measured.The model of active center including AliBu2OR' was proposed.The function of AliBu2OR was explained.
1988, 6(2): 146-151
Abstract:
Bisphenylene orthocarbonate (Ⅱ) was synthesized by the reaction of dicopper catecholate with carbon tetrachloride, and underwent cationic ring-opening polymerization with the introduction of phenyl group into the main chain. The obtained polymer with ester and ether group was verified by IR and 1H NMR spectra. Based on the analysis of the polymer structures, the polymerization mechanism was proposed. Its Tm and Tg are 254℃ and 160℃ respectively. No decomposition of the polymer was observed below 320℃.The volume expansion property of the monomer during polymerization was studied by measuring the density difference between I and its polumer at various temperatures.
Bisphenylene orthocarbonate (Ⅱ) was synthesized by the reaction of dicopper catecholate with carbon tetrachloride, and underwent cationic ring-opening polymerization with the introduction of phenyl group into the main chain. The obtained polymer with ester and ether group was verified by IR and 1H NMR spectra. Based on the analysis of the polymer structures, the polymerization mechanism was proposed. Its Tm and Tg are 254℃ and 160℃ respectively. No decomposition of the polymer was observed below 320℃.The volume expansion property of the monomer during polymerization was studied by measuring the density difference between I and its polumer at various temperatures.
1988, 6(2): 152-158
Abstract:
In this work, the stirring induced solution crystallization behaviour of cis-1, 4-polybutadiene polymerized with rare-earth catalyst (Ln-PB) has been studied by electron microscope, DSC and GPC. It has been found that when 0.5% Ln-PB toluene solution was stirred at a temperature within the range of-15° to-79℃ with a speed of 180 rpm, a kind of white swollen thread-llke substance wound around the stirrer was formed. It was seen under electron microscope that this swollen thread-Like substance consisted of fibrillar crystals of Ln-Pb parallel to each other.The amount of Ln-Pb wound around the stirrer increased with the decrease in crystallization temperature until a maximum was reached at about-65℃,then it decreased with the decrease in crystallization temperature.However,the higher the crystallization temperature,the higher the average molecular weight and the narrower the molecular weight distribution of Ln-PB which wound around the stirrer.Therefore,Ln-PB sample may be fractionated by stirring its dilute solution at a series of crystallization temperatures.
In this work, the stirring induced solution crystallization behaviour of cis-1, 4-polybutadiene polymerized with rare-earth catalyst (Ln-PB) has been studied by electron microscope, DSC and GPC. It has been found that when 0.5% Ln-PB toluene solution was stirred at a temperature within the range of-15° to-79℃ with a speed of 180 rpm, a kind of white swollen thread-llke substance wound around the stirrer was formed. It was seen under electron microscope that this swollen thread-Like substance consisted of fibrillar crystals of Ln-Pb parallel to each other.The amount of Ln-Pb wound around the stirrer increased with the decrease in crystallization temperature until a maximum was reached at about-65℃,then it decreased with the decrease in crystallization temperature.However,the higher the crystallization temperature,the higher the average molecular weight and the narrower the molecular weight distribution of Ln-PB which wound around the stirrer.Therefore,Ln-PB sample may be fractionated by stirring its dilute solution at a series of crystallization temperatures.
1988, 6(2): 159-164
Abstract:
A 300MHz solid NMR study on the compatibility of ACR (poly (methyl methacrylate-co-methacrylate), in the ratio of 1:1)-PVC (poly (vinyl chloride)) blends is reported. Spin-lattice (T1) and spin-spin (T2) relaxation time of ACR, PVC and their blends are recorded in the temperature range from 215K to 355K. Experimental results indicate that ACR and PVC are compatible with each other and the domain size is smaller than 25 nm, but heterogeneit(?)s of molecular dimensions still exist. Some problems of mechanism of compatibility and data analysis are also discussed.
A 300MHz solid NMR study on the compatibility of ACR (poly (methyl methacrylate-co-methacrylate), in the ratio of 1:1)-PVC (poly (vinyl chloride)) blends is reported. Spin-lattice (T1) and spin-spin (T2) relaxation time of ACR, PVC and their blends are recorded in the temperature range from 215K to 355K. Experimental results indicate that ACR and PVC are compatible with each other and the domain size is smaller than 25 nm, but heterogeneit(?)s of molecular dimensions still exist. Some problems of mechanism of compatibility and data analysis are also discussed.
1988, 6(2): 165-171
Abstract:
Cotton cellulose reacted with epichlorohydrin under the catalytic action of HClO4 and H2O to form 3-chloro-2-hydroxypropyl ether with a substitution degree of 0.61. The chlorine-containing product was treated with aliphatic diamines (ethylenediamine, propylenediamine, etc.) to produce nitrogen-containing cellulose which further reacted with humic acid to give black fiberous graft cellulose. This product contains 27—35% humic acid, 0.90 meq/g acidic groups, possesses 0.49 meq/g Cu2+-complexing capacity and good mechanical strength,and can be used under pH12.
Cotton cellulose reacted with epichlorohydrin under the catalytic action of HClO4 and H2O to form 3-chloro-2-hydroxypropyl ether with a substitution degree of 0.61. The chlorine-containing product was treated with aliphatic diamines (ethylenediamine, propylenediamine, etc.) to produce nitrogen-containing cellulose which further reacted with humic acid to give black fiberous graft cellulose. This product contains 27—35% humic acid, 0.90 meq/g acidic groups, possesses 0.49 meq/g Cu2+-complexing capacity and good mechanical strength,and can be used under pH12.
1988, 6(2): 172-177
Abstract:
Plasma polymerization of acetonitrile was carried out by a capacitively coupled RF plasma apparatus with external electrodes under some different reaction conditions such as discharge power. By investigating the informations provided by the polymer deposition regularities, IR spectra and elementary analysis results, the polymerization mechanism of acetonitrile in glow discharge have been investigated. The results show that acetonitrile polymerized in glow discharge mainly through hydrogen detachment for initiation at lower energy levels and the role that opening C=N triple bond played in polymerization became more important at higher energy levels.
Plasma polymerization of acetonitrile was carried out by a capacitively coupled RF plasma apparatus with external electrodes under some different reaction conditions such as discharge power. By investigating the informations provided by the polymer deposition regularities, IR spectra and elementary analysis results, the polymerization mechanism of acetonitrile in glow discharge have been investigated. The results show that acetonitrile polymerized in glow discharge mainly through hydrogen detachment for initiation at lower energy levels and the role that opening C=N triple bond played in polymerization became more important at higher energy levels.
1988, 6(2): 178-185
Abstract:
In this work, Fourier transform infrared spectroscopy was used to study the copolymerization kinetics of N-vinyl pyrrolidonc-methyl methacrylate (VP-MMA) at high conversion. Through computer simulation, copolymerization rate equation based on the free volume theory, diffusion theory and modified MH model was established. The activation energy of copolymcrization was also estimated.
In this work, Fourier transform infrared spectroscopy was used to study the copolymerization kinetics of N-vinyl pyrrolidonc-methyl methacrylate (VP-MMA) at high conversion. Through computer simulation, copolymerization rate equation based on the free volume theory, diffusion theory and modified MH model was established. The activation energy of copolymcrization was also estimated.
1988, 6(2): 186-191
Abstract:
IR spectral shifts of carbonyl vibrational absorption for ethyl acetate, which acts analogically as the structural unit of poly(methyl methacrylate), in cyclohexane, chloroform, chlorinated paraffins, poly(vinyl chloride) and chlorinated poly(vinyl chloride) were measured. The results suggest that there are specific interactions between the carbonyl groups and the chlorinated hydrocarbons which could be responsible for the apparent compatibility of poly(vinyl chloride)—poly(methyl methacrylate) and chlorinated poly(vinyl chloride)—poly(methyl methacrylate)blends.Additionally,the effects of the preparation mode of blend films on phase separation and observed compatibility are discussed.
IR spectral shifts of carbonyl vibrational absorption for ethyl acetate, which acts analogically as the structural unit of poly(methyl methacrylate), in cyclohexane, chloroform, chlorinated paraffins, poly(vinyl chloride) and chlorinated poly(vinyl chloride) were measured. The results suggest that there are specific interactions between the carbonyl groups and the chlorinated hydrocarbons which could be responsible for the apparent compatibility of poly(vinyl chloride)—poly(methyl methacrylate) and chlorinated poly(vinyl chloride)—poly(methyl methacrylate)blends.Additionally,the effects of the preparation mode of blend films on phase separation and observed compatibility are discussed.
