最新刊期
卷 ， 期 6 ， 1980
- 摘要：Based on the kinetic equations of polymerization proposed by T．Kagiya．a kinetie study on the polymerization of butadiene in hydrogenated gasoline with Ln (naph)3-Al(i-C4H9)3-Al(i-C4H9)2 Cl catalyst has been carried out．It was found that the rate of propagation is first order with respect to the con-centration Of both active center and monomer．Thus．the equation of the polymerization rate can be described as Rp=kp[C*][M]．In addition，the nature of the chain，such as cliain initiation，transfer and termina-tion were also examined．The initiation step is considered to be instantaneous at 20℃ and 50℃．but slow down at 0℃．The ratio of the rate constant of chain transfer reaction of alkyla．luminum compound to the rate constant of chain propagation is close to 1/90． The decrease in polymerization rate should be ascribed to the deactivation of the active centers at hi gher temperateure(e.g.，50℃)．The termination reaction is shown to be a bimolecular process．
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发布时间：2021-03-19 - 摘要：Some now maeroretieular ion exchange resins were prepared by the reactions of the ehloromethylated styrenedivinylbenzene copolymers with substituted phenols (or anilines)，such as salicylic acid，P-hydroxybenzoic acid，2,4，-，2,5-，2,6-dihydroxyben-zoie acid，2-hydroxy-3-naphthoic acid，gallic acid，o-aminobensoic acid etc．in the pre-8ence of Friedel-Crafts catalysts．The structures of the neW ion exchange resins were confimed by infrared spectroscopic analysis．The preparative conditions，such as the properties of solvents，amounts of catalysts，the reaction of temperature and time，the position of substituted groups，eontent of chlorine of ehloromethylated eopolymers etc.，affecting the properties of the new ion exchange resins are discussed．New ion exchange resins were widely used for saparating heavy metals，decolor-ing and the extractions and purifications of vitamines and antibiotics．
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发布时间：2021-03-19 - 摘要：The pattern of a brittle fracture surface of FEP copolymer is confirmed as fracture curve and the center of each curve is a flaw.The stress-cracking performance characterized by t50 mainly depends on the flaw density n in a semiquantitative manner. The molecular weight, molecular weight distribution, end group concentration and supermolecular structure would affect the flaw density in such a way that the larger the low molecular weight fraction, the higher is the flaw density.
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发布时间：2021-03-19 - 摘要：A kind of thermosetting phenolic resin was prepared by the condensation of linear phenolic resin (Novolak) with formaldehyde. It exhibts higher carbon content lower modulus and similar thermal stability as compared with ordinary thermosetting phenolic resin, and can be used for preparation of composites.
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发布时间：2021-03-19 - 摘要：The relationship between the content of hydroxyl groups on the surface of porous silica gels used as packings for GPC and the adsorption effects was investigated. Toluene was used as eluent and hydroxyl-end blocked polydimethylsiloxane as polymer sample. By modifying the porous silica gels with hexamethyldisilazane or by adding a small amount of a suppressant to the solvent carrier to reduced the adsorpting of polymers onto the surface of gels, was found to be unsatisfactory. An effective method for suppressing the adsorption by blocking the hydroxyl groups on the ends of polymer chains with trimethylchlorosilane has been proposed.
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发布时间：2021-03-19 - 摘要：The polycondensation of terephthaloyl chloride and p-phenylene diamine was systematically studied．High molecular weight PPTA with ntnh=5一7 were prepared and the main factors influencing the solution polycondensation of 1,4-phenylene diamine with terephthaloyl chloride were studied in detail．Experimental reaults showed that the moisture content of the reaction system．reactant coneentration and volume ratio of mixed solvents have great influences on the inherent viscosity of poly-(1，4-phenyleneterephth'alamide) ob-rained．Highest ntnh was obtained at a reactant concentration of 0.3m/l in a mixed sol-vent HMPA/DMlAC ratio of 4/1 (by volume)；at a reactant concentration of 0.35m/l，in a mixed solvent(HMPA/NMP) of 7/3 and at a reactant concentration of 0.5m/l in a mixed solvent(HMPA/TIIF) of 9/1．The water content of the polymerization system must be strictly controlled to less than 100ppm．In the early stage of polyeondensation process the ninh of the polymer obtained in-creased rapidly with time．The system gelatinized within two or three minutes while the consumption of monomers reached 100％．The reaction of polycondensation con- tinued after gelati'on and the nthn of the obtained polymer increased appreciably．
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发布时间：2021-03-19 - 摘要：We have found that the oxidation and polymerization of acrylic esters in the presence of amine are influenced both by the structures of amine and acrylic ester. Enhancing the activity of the amine with electro-positive group on the nitrogen atom or on the benzene nuclei is quite obvious. Both the oxidation and polymerization of acrylic ester containing ether bond are much easier than without.Besides MMA, 2-methoxyethyl methacrylate (MEMA) and 2-hydroxypropyl me-thacrylate (HPMA) we have also successfully polymerized acrylonitrile (NA) with dimethyl-aniline (DMA) or imethyl-toluidine (DMT) under sufficient out-gassing systems. The overall polymerization mechanism have been proposed in which DMT will promote the oxidation of MEMA first and the formed hydroperoxide will immediate-ly form redox with DMT, and then the free redical produced through redox will initiate the polymerization as usual.
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发布时间：2021-03-19 - 摘要：The oxygen absorption and oxidation of acrylic esters will promptly increase in the presence of phenyl hydrazine and polymerization will proceed by using 0.1—1％ of phenyl hydrazine．Both the rates of oxygen absorption and the rates of polymerization of several me-thacrylate esters were studied and shown to be with the following order：M→ethoxyethylmethacrylate(M→EMA) Hydroxypropylmethacrylate (HPMA)>M→ehtyl metliacrylate(MMA) The oxidation mechanism of acrylic esters in the presence of phenyl hydrazine has been proposed that the latter may withdraw the proton situated at a-carbon atom of the ether linkage or of the double bond in order to facilitate the oxidation to form the hydroperoxide．
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发布时间：2021-03-19 - 摘要：The poly (ethylebe terephthalate)-poly(tetramethylene ether) segmented copoly-mers were synthesized by using a polyether with acetoxyl end groups instead of pol-yether with hydroxyl end groups. The block copolymerization reaction has been studied, and the reaction product thus obtained was a thermoplastic elastomer with excellent properties.
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发布时间：2021-03-19 - 摘要：DSC, dynamic mechanical properties and density measurement have been performed for PET samples heat treated or stretched at different conditions. It was found that the position of the exothermal peak is obviously dependent on the degree of crystallization and orientation of the samples. The amount of heat calculated from the exothermal peak is not uniquely determined by the density of the sample, but is linearly dependent on tan 6 at 70℃, which can be used as a measure of the amount of amorphous state within a sample. At this stage of crystallization imperfect crystalline regions are formed and an abrupt increase of density is observed.
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发布时间：2021-03-19
Research Article
- 摘要：It has been found that the reaction between a PE film containning carbonyl groups and 2,4-dinitrophenylhydrazine can lead to the formation of corresponding hy-drazone on the film. Change in the amount of hydrazone was monitored by UV spec-trometry, and the effect of various factors on this reaction was studied. The present method can be used for detecting traces of carbonyl groups formed by oxidation during the processing of polymers with a sensitivity being 100 times higher than that with IR spectrometry.
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发布时间：2021-03-19 - 摘要：The relationship between polymer solution viscosity and concentration may be expressed by the following complementary equations.
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发布时间：2021-03-19
Research Bulletin
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