最新刊期
卷 ， 期 5 ， 1986
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THE CURING CHARACTERISTICS OF DIGLYCIDYL4,5-EPOXYCYCLOHEXANE 1,2-DICARBOXYLATE WITH 2-METHYLIMIDAZOL
摘要：Studies on the curing characteristics of Diglycidyl 4,5-Epoxycyclohexane 1,2-Dicar-boxylate with 2-Methylimidazol have been conducted by TBA and DSC. The whole curing process of this system proceeds in two crosslinking stages as indicted by the fact that the vitrification curve constructed from TBA data has the shape of the letter w. The increase of vitrification time after the first minimum at 80℃ implies the completion of the first crosslinking stage; the drop of vitrification time above 120℃ followed by the second minimum at 180℃ and the increase again after that, shows the comple-tion of the second stage. The limiting Tg for the first and the second crosslinking sta-ges were found to be 130℃ and 190℃ respectively. The reaction sequences accounted for these complicate curing characteristics are discussed.- 37
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发布时间：2021-03-19 - 摘要：In this paper, the kinetics of the coordination polymerization of ethylene have been studied at normal pressure with the highly active catalyst system TiCl4/MgCl2/Al(C2H5)3 (Ⅰ) in comparison with the highly active catalyst system TiCl4/MgCl2/Al(C2H5)3/Zn (C2H5)3 (Ⅱ). The specific number of active centers [C] and the propagation rate constants (kp) were determined by kinetics method for the ethylene polymerization. The value of [C] for the ethylene polymerization with system (Ⅰ) was found to be 0.02 to 0.06 mole/mole Ti in the range of poly-merization temperature 25 to 45℃,and the apparent activation energy to be 2.45 kcal/mole. The kinetics behavious of the system (II) was similar to the syste m(I),but the value of [C*] of the system (II) was much greater than that of system (I),which leads to that the catalytic efficiency increases greatly in comparison with that of the system (I). The chain transfer constants were also determined. Zine diethyl is more effective chain transfer agent that causes the great decrease in the molecular weight of polyethylene.
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发布时间：2021-03-19 - 摘要：The samples of butadiene rubber from different batch number were investigated by X-ray photoelectron spectroscopy (XPS). The double-bonding content of samples can be characterized by shake-up satellite peaks, it is shown that double-bonding content of high quality butadiene rubber is higher than those of waste rubber with obvious oxidation. From the XPS radiation study of different rubber samples, it is shown that the rubber deterioration during the course of deposit result from crosslinking and surface oxidation by X-ray radiation. Ionization potetials of butadiene rubber of different batch number were also given in this paper.
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发布时间：2021-03-19 - 摘要：In the present work, radiation crosslinking of different branched poly (vinyl acetate) have been studied and the validity of the relationship between sol fraction and radiation dose(R (S + S1/2 ) = 1 /u1q0 + (p0'/q0)Rβ) to branched poly (vinyl acetate) have been confirmed.
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发布时间：2021-03-19 - 摘要：The ammonia-catalyzed phenolic resins were prepared in different conditions (mole ratio of phenol (P) to formaldehyde (F), amount of ammonia catalyst and reaction temperature). The reaction process, the structure characterization of obtained resins and the curing process of these resins were studied by chemical analysis, 1H NMR, IR, and DTA.It was shown that the consumption of F was not changed with increasing the mole ratio of F to P when the amount of ammonia was identical. It was also shown that the reaction rate and the nitrogen containing compound was increased with increasing the amount of ammonia.The other results were also discussed.
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发布时间：2021-03-19 - 摘要：Implantation time dependence of dynamic mechanical properties of irratiated sterilized UHMW-PE hip cups, and a comparison of the properties between non-implanted hip cup sample and non-irratiated block raw sample have been studied. The results suggest that the real part of the young's modulus E' for non-implanted one is higher than that for block raw one, the magnitude of the y relaxation peak decreases and the Tv shifts to higher temperature as a result of crossliking by radiation. With increasing implantation time in vivo condition the mo-dulus E'increase and a relationship,Et=Eo exp (Dtn),hols,but the magnitude of both in-ternal friction and imaginary part of modulus E'' in γ relaxation transition increase. The cha-ngesin viscoelastic data are interpreted by that the combined chemical and mechanical effects of the body cause a rupture of networks,which inturn causes increase in density of crystalli-nity and a creation of extentive defects within the crystalline and non-crystalline regions of the sample.
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发布时间：2021-03-19 - 摘要：In the presence of Friedel Crafts' catalysts the chloromethylated copolymer of styrene-di-vinylbenzene may react with each other and form crosslinking by itself. Thus, there is obtained a new type of polymeric adsorbent, the structure of which is identified by its physical properties and infrared spectra. The Friedel-Crafts reaction is manifestly affected by the nature of the solvent, the kind and amount of catalyst, reaction temperature, length of reaction time etc. The structure of the holes and the physical properties of the adsorbent were deter-mined systematically. The properties of the adsorbent made domestically,made abroad and also of the carbonized polymers were compared. It indicates that the adsorbent reported here pos-sesses high specific surface area (1000-1300m2/g),high porosity,narrow pore distribution,high skeleton density and good mechanical property.
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发布时间：2021-03-19 - 摘要：The Thermally Stimulated Current (TSC) spectra of a series of Sub-Tg annealed Polyethylene Terephthalate (PET) specimens have been measured. It is found that there is only one peak at 80℃ above room temperature, which relates to the thermo-relaxation of frozen-in dip oles. The activation energy of such dipole motion has been calculated. The relation between the maximum current and the storage time can be explained by the free volume theory and agrees with the results from the exess thermodynamic properties. Compared with differential scann-ing calorimeter (DSC)and tensile stress-strain method, TSC is asimpler nad more sensitive method in studying Sub-Tg annealed polymers.
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发布时间：2021-03-19 - 摘要：The molecular weight separation and column dispersion for a number of SEC columns packed with various packing materials were calibrated simultaneously using narrow MWD polystyrene standards as probe. In all the case the spreading factor increases with increasing molecular weight of the probe, but its magnitude is closely related to the surface structure in the pore of the packings. As the porous silica beads with larger pore diameter possess a small specific surface area and a more smooth pore surface structure,the movement of the solute mole-cule is less restricted,the spreading factor of the high molecular weight polystyrene (M-106) is only two to three times as many as that ofthe low molecular weight one. For the crosslinked polystyrene gel the specific surface area is laregr and its pore surface structure is rougher than that of silica beads,the spreading factor of high moldcular weight probe increases inseveral ten-folds. It indicates that the movement of the solute molecule is more hindered,which could be explained by the fact that there are some shorter or longer free chain ends on the surface of the skeleton forming the permanent pore of the crosslinked organic gels.
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发布时间：2021-03-19
Research Article
- 摘要：In a capacitively coupled discharge with external electrodes, plasma polymerization of methane was studied. It was found that polymer deposition rate was accelerated when haloids were added in plasma, and effect of polymerization condition on the polymer deposition rate was confirmed at the same time. Results from IR, X-ray diffraction and elementary analysis show that plasma polymerized methane (PPM) has a cross-linked structure. PPM films have good thermostability. Refractive index and density of PPM films were determined byestablish-ed ellipitical polarization are 1.55 and 1.11 g/cm3respectively.
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发布时间：2021-03-19 - 摘要：Four poly-ω-diphenylphosphinoalkylsiloxane, including poly-ω-diphenylundecyltrialkoxy-siloxane, palladium complexes have been synthesized. They all displayed high activity for the hydrogenation of olefins and nitrobenzene. The influence of the structure of monomers, the length of carbon chain from ligand to main chain, and the incorporation of non-complexable group on the activity and selectivity of the title catalysts have also been investigated.
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发布时间：2021-03-19 - 摘要：Polystyrene-divinylbenzene (4%) copolymer beads is combined with antimony pentachloride in chloroform to form a complex containing 5.7% of chlorine (corresponding to 3.21×10-4 mol SbCl5/lg. complex beads). The complex is a strong solid Lewis acid. The SbCl5 complexed in the polystyrene is stable in air and can be stored for at least one year.The SbCl5 supported by polystyrene can be used to catalyze a lot of organic synthesis reactions in higher yield, such as esterifications, acetalations, ketal formations,etherications and the Friedel-Crafts alkylations. The complex catalyst can be used repeatedly a few times with higher yield.
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发布时间：2021-03-19 - 摘要：The initiator efficiency in the tetrahydrofuran (THF) polymerization initiated by BF3 using epichlorohydrin (ECH) as the promotor is 2.5-6 times higher than that when ethylene oxi-de promotor was used. Five chain transfers, i.e. H2SO4, H2S2O7, water, butylene glycol and acetic anhydride (Ac2O) have been studied in this paper. With the addition of even a small amount of H2SO4 or H2S2O7 to the reaction system the polymerization does not occur. In the presence of Ac2O and 5 mol-% of the initiator the conversion reached 80% after 15min. of polymerization. In such a relatively rapid reaction the molecular weight ofthe product is little influenced by the conversion and feed amount of Ac2O and therefore,can be controlled around 2000 by varying the amount of initiator charged. The end-groups of the product are mainly hydroxyls with some acetoxyls (lower than 15%). The total average functionality of the end-groups is close to 2.
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发布时间：2021-03-19 - 摘要：The vinylene-terminated tetrahydrofuran and propylene oxide liquid copolymer and it's block copolymers with styrene or methyl methacrylate were synthesized.With IR, the degree of terminal group conversion was determined. The compatibility of the block copolymers was investigated by the methods of rheovibron and dilatometer.
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发布时间：2021-03-19 - 摘要：(S)-2-(p-Vinylanilinomethyl) pyrrolidine was synthesized from p-vinylaniline and (S)-5-pyrrolidone-2-carboxylic acid. The chiral monomer ligand was polymerized to obtain the ho-mopolymer and copolymers which were used as chiral polymer ligands to modify LAH in asymmetric reduction of acetophenone.
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发布时间：2021-03-19 - 摘要：Copolyesters from terephthaloyl Chloride and 1,4-dihydroxybenzene, 2-alkylhydroquinone were prepared. Propyl and ethyl substitutions on the hydroquinone units were found very effective on depressing melting temperatures of the polymers and thus favoured the formation of a stable liquid crystalline state of the wholly aromatic polyesters.
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发布时间：2021-03-19
Research Bulletin
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