最新刊期
卷 ， 期 4 ， 1988
- 摘要：This paper reports the piezoelectricity and molecular motion of PVDF-PMMA blends. The relaxation spectrum of the blends is very similar to that of PVDF-P (VDF-HFE) and PVDF-P (VDF-TFE), but the piezoelectricity of which are wearker than that of PVDF-P (VDF-TFE). When the content of PMMA in the blend is equal to 3%, its piezoelectricity is nearly the same as PVDF, but the temperature of depolarization is higher than that of PVDF, PVDF (VDF-HFE) and PVDF (VDF-TFE). The piezoelectricity of PVDF-PMMA blends decrease with increase of the content of PMMA in the blends,owing to the lower concen-tration of the dipoles in the noncrystalline phase.
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发布时间：2021-03-19 - 摘要：In this work，the stirring induced solution crystallization behaviour of cis-1，4-polybuta-diene 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 tern-perature within the range of -15°to -79℃ with a speed of 180 rpm，a kind of white swol-len thread-like substance wound around the sti stirer was formed． It was seen under electron microscope that this swollen thread-like substance consisted of fibrillar crystals of Ln-PB paral-lel 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 一65℃．then it dec reased with the decrease in crystallization temperature．Howevcr，the higher the crystallization tem-perature，the higher the average molecular weight and the narrower the molecular weight distri-bution of Ln-PB which wound around the stirrer．Therefore，Ln-PB sample may be fraction-ated by stirring its dilute solution at a series of crystallization ternperatures．
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发布时间：2021-03-19 - 摘要：PEG-PLA block copolymers were synthesized using polyethylene glycol (PEG) and lac-tide (LA) in the presence of low toxic stannous octoate. The copolymer structure was determined by 13C NMR and the average block leng this were calculated. The results showed that LPKG was unchanged during the reaction process, but LPLA depended on polymerization time and LA content in the feed. This is in agreement with the character of step polymerization. The mechanism of polymerization was also assumed from experimental results.
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发布时间：2021-03-19 - 摘要：In this paper it is discussed that hydrophobic group, the third unit, was introduced in a hydrpphilic molecular chains by the reactions of ester exchange and esterification when hy-droxyethyl methacrylate and methacrylic acid copolymerized in alcohol.
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发布时间：2021-03-19 - 摘要：A MgCl3-supported TiCl4 catalyst comprising NdCl3 (called SN-1 catalyst) gives good yield which containing 4-85 mol% styrene-unit content in the products for the copolymema-tion of ethylene and styrene. The products have been fractionated by successive solvent extraction with suitable solvents and have been characterized by X-ray diffraction, DTA, TBA and TEM. The results show that the principal parts of copolymerization products are copolymers consisted of long sequences of ethylene-unit. Special mechanical properties of the products were observed. The influences of monomer ration,concenration of catalyst,molar ratio of Al/Ti and reaction temperature on copolymerization of ethylenestyrene have been inveestigated as well.
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发布时间：2021-03-19 - 摘要：Various block and multiphase copolymers were made from Vinylene-Terminated liquid polymer macromer. The compatibility of the copolymer of Vinylene-Terminated propylenc oxide liquid polymer and styrene has been studied. Using the methods of dilatometer, IR, stress-strain curve, DSC, and electron microscopy, the components' separation was found.
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发布时间：2021-03-19 - 摘要：The curing characteristics, kinetics and reactivities of the diglycidyl ether, diglycidyl ester type resins and aliphatic cycloepoxy resins cured with imidazole have been studied by DSC. The results of dynamic and isothermal DSC show that thd whole curing reactions proceed in two stages, that the apparent activation energy in the first stage of various epoxy resin, except the H-71 epoxy resin, is higher than that in the second stage, and that the reactivity of the cycloaliphatic epoxy resins with imidazole is higher than those of bisphenol A type epoxy resin and diglycidyl tetrahydrophthalate resin. It was found that in the co-curing systems of the aliphatic and cycloaliphatic epoxy re-sins with imidazolem,m-phenylene diamine and anhydrides as curing agents,the former com-ponent can accelerate the reaction considerably.
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发布时间：2021-03-19 - 摘要：Polyether polyurathane based on 4,4'-diphenylmethane diisocyanate (MDI), N-methyl di-ethanolamine. (MDEA) and pplytetramethylene oxide (PTMO) were synthesized in the tertiary molar ratio of 2:1:1. As a result of the reaction of the tertiary amine of MDEA with γ-propane Sulfone, a series of zwitterionomers were prepared in different degrees of sulfo-nation. The dielectric properties of these samples were determined in different temperatures ( - 150 to 30℃) and frequencies (20 Hz to 100 kHz), It was found that as the degree of sul-fonation increases,the real permittivity (ε') is increased and the dielectric loss peak of a-relaxation shifts to lower temperatures indicating as improvement of phase seperation and the activation energy of a-relaxation (Ha) was decreased while thet of β-relaxation (Hβ) was nearly unchanged. The results of the dielectric measurement coincide with the dynamic me-chanical analysis.
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发布时间：2021-03-19 -
SYNTHESIS OF A SILANE COUPLING AGENT THROUGH HYDROSILYLATION CATALYZED BY POLYMER PLATINUM COMPLEXES
摘要：Five new polysiloxane-platinum complexes ("Si-Pt-1" - "Si-Pt-5") have been prepared by reaction of chloroplatinic acid with various silica-supported polysiloxanes(1-5) bearing ligand group CHC6H4N(CH3)2, CHC6H4OH, - N(OC-CH3)2,-CN and - COOH. It was found that these polymer platinum complexes are very efficient catalysts for the hydrosilylation of allyl glycidyl ether by trimet-hoxysilane. Under mild conditions (80℃,30min), the catalyzed reaction produced a silane coupling agent, γ-glycidoxypropyltrimethoxysilane,in a high yield(72-98%).The stability of the polymer platinum complex"Si-Pt-1"containing -S-S CHC6H4N(CH2)2ligand group has been investigated. It has shown that the catalyst can be re-used many times without appreciable decrease in catalytic activity.- 2
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发布时间：2021-03-19 - 摘要：A new method, taking the molecules as circle unit, which is different from Flory and others' method, which took the functional groups as circle unit, has been used to derive the equation for the critical condition of gel formation of the reaction between ∑Aai and ∑Bb1 kinds of molecules. The new equation, expressed with number-average functionality or number fraction of molecules, instead of weight-average functionality or number fraction of functional groups, is more agreeable to Flory's experimental results. Based upon the theroretical analysis,the chemical reaction is molecular reaction. Therefore,it is more reasonable to use molecules as circle unit than to use functional groups as circle unit.
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发布时间：2021-03-19
Research Article
- 摘要：N-p-B rPhMA was synthesized by the interaction of p-bromoaniline with methacryloyl ch-loride in the presence of triethylamine．This new monomer was characterized by IR and 1H-NMR spectroscopy．The N-P-BrPhMA-co-MMA bulk copolymers were prepared and characterized by IR and 1H-NMR method．The compositions of the copolymers were determined from the areas of the phenyl gro-up and methoxy group proton peaks in the proton NMR spectra．Reactivity ratios were calculated from the composition data by the Fineman-Ross meth-od；the following values were obtained：r1=3.25+0.02(MMA)，r2=0.40+0.02(N-p-BrPhMA) for MMA-co-N-p-BrPhMA，r1=1.05+0.02(MMA)，r2=0.54+0.02(N-PhMA) for MMA-co-N-PhMA．The MMA-co-N-p-BrPhMA bulk copolymers are harder than PMMA homopolymer．When the amount of the N-p-BrPhMA chlanges from 2.63％ to 28.7％ the hardness of the bulk copolymers increases from 20.4 Kg／mm2 to 27.0 Kg／mm2．
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发布时间：2021-03-19 - 摘要：This work deals with the group transfer polymerization (GTP) of methyl methacrylate and some acrylates, with ethyl 3-ethoxy-3-trimethylsiloxyacrylate (ETSA) as initiator and Et4NHF2 as catalyst. Monodisperse polymer with predetermined molecular weights can be obtained by adjusting the monomer/initiator ratio. "Auto-acceleration" can be avoided by decreasing the catalyst concentration.
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发布时间：2021-03-19 - 摘要：In the presence of alkyl benzene sulfonic acid the nitrogen-carbon bond of three-member rings might be broken at the crosslinking points of photosensitive polymer of cyclized poly isoprene-diazide system and then the broken photocrosslinking polymer was degradeted. The degradation products can dissolve in halogenated alkenes. The degradation rate of the photo-croaalinking products was dependent on the carbon chain size of alkyl group of alkyl benzene sulfonic acids and the reaction temperature.
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发布时间：2021-03-19 - 摘要：β-Acryloxypropionic acid and styrene copolymers were synthesized through radical copo-lymerization with AIBN and BPO as initiators. The major factors that affected the copoly-merization were studied. The copolymerization reactivity ratios of monomers were determined by YBR method and the following data were obtained:rst = 0.5863, rAPA = 0.2826,QAPA = 0.54,eAPA = 0.44.
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发布时间：2021-03-19 - 摘要：The initiator efficiency (If) in the polymerization initiated by BF3-epichlorohydrin is about 2-4 times higher than that by BF3-propylene oxide (PO) catalyst system. With decreasing the concentration of initiator or increasing the amount of PO fed, as BF3-PO catalyst system was used, the If value increased. The influences on the molecular weight and yield of the polyether obtained were studied. The average hydroxyl end-group functionality of the product was determined to be 2.
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发布时间：2021-03-19 - 摘要：On the wide varities of optically active polymers, PTrMA is one of the most attractive because its chirality derives from the helicity of polymer chain in one hand screw. In the present work, TrMA was synthesized with Pb(NO3)2 instead of AgNOa reported. With chiral diamine (-)-Sparteine and (+)-DDB as ligands, optically active PTrMA was obtained with specific rotation ([α] DM + 356°) higher than that of reported so far. The influence of polymerization condition on polymer properties was discussed. Other ligands and initiators for obtaining optically active PTrMA were also investigated.
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发布时间：2021-03-19
Research Bulletin
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