最新刊期
卷 ， 期 2 ， 1983
- 摘要：A new method of graft copolymerization of acrylamide(AAM)on poly(etherure-thane) (PEU) which was prepared from poly(oxytetramethylene) glycol (PTMG)，4，4’-diphenylmethane diisocyanate(MDI) and ethylene diamine(E) or butanediol(B) extender was investigated．Hydroperoxide group was first introduced onto the surface of poly(ether-urethane) through photo-oxidation in the presence of hydrogen peroxide，then it was reacted with ferrous ion or N，N-dimethyl toluidine (DMT) to initiate AAM graft copolymerization on PEU surface．The graft reaction COuld be carried out at low temperature with high speed．The grafted PEU film became opaque and its water absorption increased．The forma tion of graft copolymer has been verified by its water absorption ％ and the scanning electron microscopy photographs．Some model compounds of PEU soft segment and hard segment were synthesized in order to clarify the graft reaction mechanism．The results of oxidation and graft copoly-merization of model compounds showed that this graft copolymerization possesses higher selectivity，and it takes place predominately in polyether segment because the ether linkage in soft segment is very sensiti；ce to oxidation and can form hydro-peroxide easily．Thus，the grafting site appears to be at a-carbon of the ether linkage．
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发布时间：2021-03-19 - 摘要：The polycondensation of p-phenylenediamine and terephtha]oyl chloride in amide solvent system has been studied．In order to obtain high molecular weight poly (1，4-phenyleneterephthalamide) (PPTA)，the solvation of PPTA with the solvents and the competitive side reaction of the solvents with terephthaloyl chloride in amide-salt system were investigated．We can observed from NMR data．the proton resonance of the amide group of these model compounds shifts markedly to lower field due to the effect of solvation．The magnitude of these shifts depends on the kind of solvent and the concentration of the salt used．DMAe and NMP are the solvents which react with terephthaloyl chloride comptitively in the polyrcondensation proeess．
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发布时间：2021-03-19 - 摘要：The relation between polymerization conditions of vinylidene fluoride and content of head-to-tail chain in the polymer have been studied. It shows that the content of head-to-tail chain of the polymer are related to its polymerization temperature, but are not related with the kind of initiators used. Therefore, poly (vinylidene fluoride) with low content of head-to-head chain (ca. 3%) can be prepared under lower polymerization temperature. Plot of content of A chain against melting points of the polymer is linear,which can be expressed by an equation：A=24.8+0.362 Tm(%).
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发布时间：2021-03-19 - 摘要：Multiple melting behavior of Nylon 1010 has been investigated by using DSC instrument. Effect of partial scanning, partial scanning and annealing, heating rate, cooling rate and successive annealing at lower temperature on the melting curve was studied. Experimental results indicate that the sample undergoes a process of continuous melting and recrystallization during DSC scanning. Nylon 1010 contains a distribution of crystallites of different degrees of perfection which is strongly dependent on its previous thermal history. From the structural reorganization point of view,the orign of double and multiple peaks on the melting curve is explained.
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发布时间：2021-03-19 - 摘要：In the course of cationic emulsion polymerization, octamethylcyclotetrasiloxane (D4) is first emulsified into "transition particles" with bigger diameters, on the surface of which the ring-opening reaction of D4 and the addition of D4 to OH-ended siloxanes take place. The particles are then transformed into stable emulsion particles are transformed into stable emulsion particles with extremely small and uniform particle size. The condensation of OH-ends of the polydimethylsiloxanes proceeds predominantly in the emulsion particles.
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发布时间：2021-03-19 - 摘要：The following two new compounds have been synthesized by Diels-Alder reaction both in about 80% Yield.Compound (Ⅰ) can be used as an additive for compounding silicone rubber. The resulting elastomer shows good thermal stability and fair mechanical properties after aging at 300℃ for 150 hours.. Compound (Ⅱ) can be used as a crosslinking agent for the hardening of RTV silicone rubber. The resulting elastomer shows good heat resistance after aging at 300℃ for 48 hours.
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发布时间：2021-03-19 - 摘要：The kinetics of the polymerization of isoprene with Nd(naph)3-Al(i-Bu)3-Al2 (C2H5)3Cl3 catalyst system has been studied in heptane in the temperature range of 20-50℃. The polymerization rate was found to be first order and 1.7 order to monomer and catalyst concentration respectively and the observed activation energy for the polymerization is 9.0 kcal/mole. Based on above mentioned results a mechanism of catalyst formation was proposed. Data obtained in the polymerization of isoprene with successive addition of monomer indicate that there is no deactivation of active centers in the studied temperature range. Effects of the polymerization conditions on the intrinsic viscosities of polymer were also investigated.
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发布时间：2021-03-19 - 摘要：The polymerization of dimethylaminoethyl methacrylate (DMAEMA) initiated by lauryl peroxide (LPO) has been investigated. The rate equation of the polymerization was obtained as Rp = Kp [DMAEMA]1.5 [LPO]0.5, and the overall activation energy of polymerization was determined as low as 9.7kcal/mol (40-70℃). It is suggested that the redox system from the tertiary amino group of the monomer and LPO initiated the polymerization of monomer itself.
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发布时间：2021-03-19 - 摘要：Aromatic tertiary amines, especially N, N-dimethyltoluidine, are effective sensitizer for photopoymerization of AN. The rate of polymerization is proportional to 1.62 power of [AN] and 0.62 power of [DMT]. The apparent activation energies of polymerization have been estimated to be 7.8kcal·mol-1 in bulk polymerization and 4.2kcal·mol-1 in DMF solution polymerization, respectively. The effect of solvent on the rate of polymerization was also studied The greater the polarity of the solvent, the faster the rate of polymerization is. Theinduction period increases and the rate of polymerization decreases with increasing amount of oxygen.
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发布时间：2021-03-19 - 摘要：Sub-macrostructure of poly(ethylene terephthalate) has been studied with polarized-light microscope, scanning electron microscope and SALS methods. It has been shown that there are at least two types of crystal morphology. In one type, the optical axis is perpendicular or parallel to the radius of the spherulite; in another type, the optical axis takes an angle of 45° with respect to the radius.
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发布时间：2021-03-19
Research Article
- 摘要：The expressions for various molecular parameters of graft copolymers are derived by means of the law of total probability and some properties of probability generating function.
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发布时间：2021-03-19 - 摘要：In this article an improved method of suspension polymerization of N-vinylcar-bazole is introduced. Instead of common zinc oxide powder we use photosensitive zinc oxide powder as dispersion agent. Thus, photosensitivity of polymer is increased. Using benzene in place of chlorobenzene to dissolve initiator can lower the temperature of polymerization. The initator can be dissoved in hot water without using organic solvent and the resulting solution is added to reactants mixture to initiate the polymerization reaction. In this procedure,less reagents are used and pollution isdimini-shed.
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发布时间：2021-03-19 - 摘要：In this work，the coupling graft of polymers is treated by means of kinetics．The expression of the molecular weight distribution of grafting copolymer is a bi-dimen-sional distribution function with two variables n and m．where n is defined as the total degree of polymerization of the branches and m represents the degree of polymeriza-tion of back-bone．On the basis of this，all of the molecular parameters，such as the number and weight average molecular weights，the grafting distribution，the grafting degree and the grafting success，etc.，can be derived． If the termination of the hying prepolymer is present during the grafting reaction process，parameter λ introduced in this paper must be regarded as the grafting efficiency，and some equations obtained must be revised．The revised equations are still applicable for some other types of gra-fting reaction．For instance，these theoretical equations are appropriate also for the free radical copolymerization of styrene on polybutadiene．
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发布时间：2021-03-19 - 摘要：It hs been found that the title copolymers are more heat-resistant than polymethyl methacrylate. When the amount of the amide changes from 5 to 10% the softening points of the copolymers increase from 140 to 154℃, presumably due to the increase in hydrogen bonds through the introduction of amide groups.In comparison with MAD-MMA copolymers, the φA-MMA copolymers have better water-resistance.
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发布时间：2021-03-19 - 摘要：A series of new linear polyarylsulphone-polyetherurethane segmented copolymers was synthesized from diisocyanate terminated polyurethane with hydroxyl-terminated polyarylsulphone oligomer through hydrogen polyaddition reaction. The structure and properties of the copolymers have also been investigated preliminarily. It was found that the introduction of arylsulphone segment into the main chain could produce the following effects: to facilitate phase separation in the copolymer, to improve heat resistance and hydrophilic property of the copolymer.
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发布时间：2021-03-19
Research Bulletin
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