最新刊期
卷 ， 期 2 ， 1992
- 摘要：The crystallization behaviour of poly (vinyl alcohol) (PfAl)/poly (vinyl pyrrolidone) (PVP) blends was investigated by using DSC, WAXD and SAXS. The crystallinity of PVA1 was decreased with increasing of the content of PVP and there was no any crystallinity when the content of PVA1 was less then 50 wt.%. Comparing with plain PVA1 the difference between Tm, and Tg of blends was low which emerged that PVP could prohibit the crystallization of PVA1 in blends. The kinetic crystallization behaviour could be deseribed by Avrami equ-ation. The rate of crystallization of PVAl in blends was slower than plain PVAl which could be verified by the facts that the supercooling of blends was increased and the growing rate of spherulites and the kinctic constant were decreased. Long spacings,the thicknesses of lamellae and transition layers of annealing samples were higher than unannealing one.The composition had a dramatic influence on long spacings,some extent of influence on the thickness of lamcllae and little on the thicknesr of transition layers.
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发布时间：2021-03-19 - 摘要：The phase transitions from nematic mesophase to isotropic state (N-I) and from isotropic state to nematic mesophase (I-N) of the poly (P-phenylene benzobisthiazole)-methyl sulfonic acid solution (PBZT/MSA) have been studied by depolarized light intensity and polarized microscopy.It was found that the phase transition temperature is a function of theconcentration of PBZT/MSA. The atructural long range order of PBZT/MSA induced by shearing can been enhanced by increasing temperature.The study of kinetics of I-N phase transition shows that the transition is nucleation con-trolled which can be described by an Avrami equation. The Avrami exponent is about l which suggests the nucleation is followed by rodlike growth.The results show that the depolarized light intensity is a simple and an effective method for study of the process and the kinetcs of phase transitions of liquid crystalline polymers,es-pecially for lyotropic liquid crystalline polymers.
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发布时间：2021-03-19 - 摘要：The emulsion of copolymers of acrylates with epoxy group were preparedand characterized by means of swelling capacity. The self crosslinkingreaction of the copolymer was studied by FT-IR. It has been found that theswelling capacity of the crosslinked copolymer films decreased with increaseof the glycidyl methacrylate (GMA) content. The activation energy of thecrosslin-king reaction was obtained. A mechanism of the crosslinking reactionwas proposed.
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发布时间：2021-03-19 - 摘要：A superdrawn technique called crystal real drawing has beea applied to obtain the oriented isotactic polypropyIene (i-PP) films．Orystal mat of ultrahigh moIecular weight i-PP(Mw-4×106) obtained by crystallization from its dilute xylene solution，exhibits a dramatlcally high de-formability compared to both the low toolecular weight mat and the mek-crystallized forms．such cryatsl mats are prepared to a series of samples with the various draw ratios and the highest draw ratio can be achieved up to 69．An X-ray diffraction photograph shows that the c-axis of the lamellar crystals in the original mat orient preferentially in the normal direction of the mat plane，and such crystals had already been split and c-axis orientation had been turned to parallel with the draw direction in the draw ratio range of 110 and D040 decrease as the draw ratio is in-creased，but the long period L found to becomelarger with the draw ratio raise up to the high value．These results indicate that lamellar crystals are deformed through a chain folds unrave-ling and then partially recrganized into a fully straight crystalline structure．
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发布时间：2021-03-19 - 摘要：Liquid crystalline(LC) polysiloxane with cholesteric group in side chain has been prepared by a polyhydrosilylation reaction of poly(hydrogenmethylsiloxane) with a terminal alkenic cholesteric group. The structure of these polymers were confirmed by analysis of IR and NMR. Its phase transfomation was studied by optical microscope and DSC. The results showed that the polymers form a LC phase in certain temperature range, and the temperature range depends not only on the flexibility of the flexible spacer, but also the content of cholesteric side chain uni-ts. Therefore the temperature range fo LC phase can be controlled by changing the content of the cholesteric side chain units and the structure of the flexible spacer.
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发布时间：2021-03-19 - 摘要：The isothermal crystallization kinetics of LDPE/EPO blends have been investigated by DSC. It indicated that blends are of three-dimensional growth a thermal nucleation. The nucleation process in every crystallization temperature belong to regime II. A new kinetic equation of non-isothermal crystallization was derived by combining Avrami and Ozawa equations. Some parameters of crystallization kinetics can be obtained from the new kinetic equation. The kinetics of non-isothermal crystallization of a LDPE/EPO blends has been investigated by using differen-tial scanning calorimeter. The experimental results analyzed showed agreements with the new kinetic equation.
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发布时间：2021-03-19 - 摘要：Dibutyltin maleate (DBTM) homopolymer [Poly(PDBTM)] was synthesized in benzene solution at 80℃ using benzoyl peroxide as an initiator. The poly merization rate anu ultimate converation of monomer, even on raising the initiator to over 10 mol%, were low. The solubility, intrinsic viscosity, IR spectrum and thermal behavior of Poly (DBTM) were studied. Poly (DBTM) was a white ahd brittle solid, and is insoluble in common organic solvents. The polymerization kinetics of DBTM has been rtudied in benzene solution rate equation.The apparent activation energy of polymerization was found to be 17.5kcal/mol.
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发布时间：2021-03-19 - 摘要：A group of pyrylium salts with different substituents has been synthesized in this work. Their fluorescence life time, quantum yield and quenching constant by BVE have also been measured. It was found that a strong interaction was observed between BVE and pyrylium salt which contains an electron-withdrawing group, and contrary, the introduction of electron-repulsive groups to the pyrylium salt will decrease this effect. It indicated that these reactions possess the characteristic of electron transfer. Because,the amount of double bond of BVE decreases in the process of BVE polymerization,therefore,in the same time the quenched flu-orescence of pyrylium salt can be recovered gradually. This phenomenon may be used as a probe for studying the process of photo-induced initiated cationic polymerization of BVE.A preliminary mechanism for the photo-initiated polymerization of BVE by pyrylium salt was also discussed.
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发布时间：2021-03-19 - 摘要：Heparinized cross-linked polymethacrylic acids were synthesized by tetravalent eerie ion initiation in aqueous solution under mild condition. The antithrombogenic properties were determined by TTT and RTT. The preliminary results showed that these heparinized polymers are antithrombogenic.
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发布时间：2021-03-19 - 摘要：The positron annihilation lifetime spectra of four different kinds of specimen of polyethylene teraphalate (PET): amorphous, 54℃ annealed, 180℃ annealed and 85℃ stretched have been measured in a temperiture region of 22-180℃. According to the results of least square curve fitting to the spectra, it can be seen that the temperature curves of the longest lifetime annihilation parameters sensitively respond glass transition and crystallization of the PET specimens.
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发布时间：2021-03-19 - 摘要：Kinetic behavior of MMA-EGDM copolymerization was inverstigated in the presence of toluene and 2-ethylbutanol. Effect of monomers ratio, properties and amounts of porogenic agent is discussed for the kinetics of copolymerization.
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发布时间：2021-03-19 - 摘要：Some dilute solution properties of chitosan with different degree of deacetylat-ion (D.D) have been studied by viscometry and light scattering in the 0.1mol/l CH3COONa/0.2mol/l CH3COOH buffer solvention. The results indicated that the va-luesf or constant k and a in the Mark-Houwink equation were regularly dependent on D.D And it was found that the higher the D.D was, the larger the molecular size z2/1, intrinsic viscosity [η] and the expansion factor aη became, under the same molecular weight because of the polycation behavious of chitosan.But the co-nformation parameter and characterstic ratio Coo diminished with increasing of D.D.
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发布时间：2021-03-19 - 摘要：The multiphase structures and chain dynammics of fluorine-containing ionomers were investigated by means of C-13 spin-spin relaxation time (T2) and spin-lattice relaxation time (T1). The biexponential spin-spin relaxation of main chain carbon atoms of ionomers was observed. The fast relaxation component described the interface between ionic micro-domains and polymer matrix, ahd the slow relaxation component related to the polymer maltrix. The polymer chains in the interface arranged more regularly than that in continuous phase.The dynamic activities of polymer chain of ionomers formed by different metal ions had something to do with the characterization of metal ions and the fine structures of ionic microdomains,and it decreased with the increasing of the content of carboxylic groups and ionization degree.
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发布时间：2021-03-19 - 摘要：In the presence of a Friedal-Crafts catalyst, the benzoylated PPO (APPO) was prepared by the reaction of PPO with benzoyl chloride. By changing the ratio among PPO, catalyst and benzoylating agent, we obtained a series of samples (APPO) with different substitution levels. The misoibility of PS with various substituted PPO were studied by DSC. When the degree of benzoylation is more than 49 mol%, the blends of APPO/PS show two T, in DSC curves. The effect of temperatures on he phase behafior of A49 PPO/PS blend were studies by DSC.The blend system was found to exhibit both UCST and LCST behavior. It is also found that the thermally induced phase separatioh is reversible.
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发布时间：2021-03-19 - 摘要：In this paper, a new equation of state for polymers is derived theoretically. A comparison of the equation with experimental data is made for 6 polymers at different temperatures and pressures. The results obtained show that the equation of state is suitable to describe the isothermal compressing behaviour of polymers in the state without transitions.
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发布时间：2021-03-19 - 摘要：The relative formation rates of castor oil polyurethane and acrylic or vinyl polymer during formation of the simultaneous grafted interpenetrating polymer networks (IPN) were compared by using IR spectrophotometry. The relation between gelation point and gel content of IPNs with different compositions were determined. Tensile strength of the IPNs containing different acrylic or vinyl polymers varies with polyurethane content and kind of acrylic or vinyl monomer. TEM of the IPN indicated that polyurethane existed as domains in acrylic polymer. A wide glass transition temperature of the IPN occurred in the dynamic mechanical spectrum of the IPN.
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发布时间：2021-03-19
Research Article
- 摘要：Based on the method of ε-NTU, a mathematical modeling of ester-interchange reaction for dimethyl terephthalate (DMT) with ethylene glycol (EG) by acetate system was simulated, and, in addition, the corresponding kinetic equation is obtained by using the theoretical method of simulation. That is,-(dc)/(dt)=kc(c+k')where:-(dc)/(dt)= the reaction rate of the monomer, C -concentration of the monomer, θ-Suitable parameterk,k'-constant (k'=θ/k)The experimental results have showed that the ester-interchange reaction is a reaction neither first order or second order nor third order,but it is a reaction of secondary linear type. Yamanis[2] doubted the correctness of the method that has been proved.Moreover,we have suggested the physical meaning of parameters.
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发布时间：2021-03-19 - 摘要：Group trahsfer polymerization of methacrylates with 1-trimethyl siloxy cyclohexene (TSCH), 1-(N,N-dimethyl amino)-1-trimethylsiloxy butene-1 (DMTB) and ethyl 2-ethyl-3-ethoxy-3-trimethyl siloxy acrylate (EETSA) as initiators, Bu4NH(C6H5CO2)2 and Et4NHF2 as catalysts was investigated. The dependence of the control of molecular weight and low po-lydispersity on the catalyst concentration, monomer/initiator ratio, reaction temperature, solvent, steric hindrance of methacrylates, the course of the reaction has been studied. Polydi-spersity decreases with decreasing of induction periods. When Et4NHF2 concentration is 0.008-0.012 mol/L,molecular weight control is good.
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发布时间：2021-03-19 - 摘要：Five PVC samples (U-PVC) were prepared in water suspended system at monomer unsa-turation vapor pressure. The molecular weigh's and dehydrochlorination rates (De-HCl) of these samples and five commercial PVC samples (S-PVC) were determined. Experimental data showed that the thermal stabilities and molecular weights of U-PVC samples decreased wifh decreasing the monomer unsaturation vapor pressure (Pm/Po) in the preparation process. It was found also that there was a good linear correlation between 1/Mm, De-HCl and Pm/Po This result indicated the important role of the terminal structural defect in the dehydrochlorination of PVC.The mechanism of formation of terminal structural uefects was discussed.
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发布时间：2021-03-19 - 摘要：The group transfer polymerization of p-ethoxy biphenyl methacrylate with MTS initiator and bibenzoate catalyst was reported. The polymer exhibits liquid crystalline property although the mesogenic side chains are directly fixed to the polymer backbone. The effects of the initiator and catalyst concentration, solvent, temperature on polymerization were studied.
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发布时间：2021-03-19
Research Bulletin
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