最新刊期
卷 ， 期 6 ， 1983
- 摘要：Upon continuous stress relaxation of the filled silicone rubber, especially the vulcani-zate filled with octamethylcyclotetrasiloxane-modified silica at 260-300℃, the relative stress decreases first to a minimum and then increases, proportionally with time up to a certain limit. The change can be described approximately by the formula:f(t)/f(0) - A1e-K1e + A2e-K2t + k3t + A3Here the rate constant k2 is ascribed to the degradation of the rubber matrix, k3 to the cros-slinking of the stretched chains, k2 to the cleavage of the linkage connected with filler.
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发布时间：2021-03-19 - 摘要：In this paper, structure of the aggragative state ot poly (ethylene terephthlalte)-poly (tetramethylene ether) multiblock copolymer was studied by IR, DSC and electron microscope. The block ratio of the copolymer and ts sequence distribution was measured by 1H-and 13C-NMR method.
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发布时间：2021-03-19 - 摘要：The curing behavior of diglycidyl-4, 5-epoxycyclohexane-1, 2-dicarboxylate with m-phenylene diamine has been studied by TBA. It is shown that the whole curing process proceeds in two stages, i.e. curing reaction during temperatures below 100℃ mainly occurs at the epoxides on the esterlinkages, whereas a rapid increase in reaction rate of the remaining epoxides on the cyclohexane ring occurs only at temperatures above 130℃. Between the temperature range from 100℃ to 130℃, the reaction of the epoxides on the esterlinka-ges reaches completion,while the reaction rate of the epoxides on thecyclohexane ring be-gins to increase gradually. The apparent activation energy is 13.2kcal/gram-mol.
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发布时间：2021-03-19 - 摘要：The polymerization of acrylonitrile in aqueous nitric acid solution with sodium nitrite as initiator has been studied. The rate of polymerization can be expressed by following equation:Rp = Ae10.800/RT [AN]2.3 [NaNO2]0.17-1.0[HNO3]1.0-0.67In the copolymerization of acrylonitrile and methyl acrylate, the reactivity ratios was found to be 0.96 and 1.17, respectively, indicating a free radical mechanism.According to the results of polymerization kinetics and infra-red analysis, it is suggested that the initiation mechanism of acrylon trile in aqueous nitric acid solution by sodium nitrite is analogous to thesecondary initiation by electrolysis or corrosion of metals.
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发布时间：2021-03-19 - 摘要：A relationship between the glass transition temperature of a polymer and the cross-sectional area of a single molecular chain is established by taking the intermolecular action into account. It was considered that cross-sectional area of a single chain determines the flexibility of macromolecular chain and this was confirmed from the energy of rotational iso-merization of 1,2-polybltadiene.
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发布时间：2021-03-19 - 摘要：The morphological structure and crystallization kinetics of some oil-extended polybu-tadiene rubber polymerized with lanthanide catalyst were studied with EM, WAXD, TGA and dynamic mechanical measurement. It has been found that No. 9 oil has higher molecular weight than the rest; its compatibility with rubber is much lower; some kind of chemical linkages may exist between oil and rubber when vulcanized; and the No. 9 oil-extended rubber shows stress induced crystallization. These all contribute to the higher tearing stre-ngth possessed by the No.9 oil-extenede polybutadiene rubber.
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发布时间：2021-03-19 - 摘要：Several polybutadiene samples prepared with different catalysts Were studied by 13C-NMR. It is shown by analyzing the molecular chain of polybutadiene that there are three sequences (cis 1,4-sequence, trans 1,4-sequence and 1,2-sequence) and seventeen aliphatic carbon nuclei in it. These nuclei contribute to the sixteen peaks on the 13C-NMR spectrum of polybutadiene. A group of empirical parameters is obtained by analyzing the chemical shift data of the peaks. When using them in our case, the calculated values of chemical shift of the peaks agree quite well with the experimental ones. A T4peak,the fouth peak oftrans 1,4sequence,was first discovered by the present work.Quantitative treatment of the se-quence structure ofpolybutadiene was preliminaryly studied.
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发布时间：2021-03-19 - 摘要：A low molecular weight polyether with B15-C-5 in the side chain was synthesized by the reaction of hydroxymethyl benzo(15-crown-5) with a copolymer of β-iodoethyl glycidyl ether and THF. This polymeric crown ether possess good coordination ability with K+, Na+ and is an effective phase-transfer catalyst for some organic reactions. In addition, this polye-ther is a brown viscous oil, having reactive hydroxyl groups, and can be vulcanized with toluene diisocyanate to form a elastic film or immobilized on silica gel.
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发布时间：2021-03-19 - 摘要：The transition in the malt of FEP copolymer was detected by differential scanning calorimeter and torsional braid analysis techniques．In order to darify the nltture of the transition．the changes of malt viscosity with temperature and shear rate were investigated by capillary rheometer and micro．paraUel type rheometer．The result obtained shows that，theplot of ln n vs．1／T of FEP copolymer at constant shear rateor sheading stress does not show a linear relationship as usually observed in the conventional polymer melt but an ano-malous increase of n，when the temperature incneases above the transition temperature．This rheological behavior is similar to that of low molecular liquid crystal．But no birefrin-gence in the meh can be perceived under crossed polarizing microscope．Based on these ex-perimental facts，a model was presented to explain this transition．
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发布时间：2021-03-19 - 摘要：9-Amino-pelargonic acid was polycondensed in boiling inert paraffin hydrocarbon medi-um．The water formed during the reaction was immediately carried away by the vapor of the medium．By using this method．the polycondensation，ran very rapidly，and the extent of reaction p reached more than 95％，within 15 min，and after three hours heating，psurpassed 99％．The average molecular weight became over 40,000．These results have never been achieved by other authors reported in literatures．Because p can be pushed to over 99％，it is possible to study the complete course of this polycondensation reaction It was found that the reaction followed a second order kine-tics from the begining up tO p=9996，beyond which the system became SO viscous that a viscosity factor should be considered．Since the increase of viscosity will decrease the reac-tion rate，and the increase of molecular weight，i.e．a decrease of the concentration of the end group．will increase the viscosity．it follows that the decrease of the concentration of the end group will decrease the reaction rate, such that the reaction changes into a third order kinetics as the extent of reaction goes over 99％．
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发布时间：2021-03-19
Research Article
- 摘要：The sodium salt of poly-6-sulfohexyl methacrylate (PSSHMA) has been synthesized. In 0.15M NaCl, refractionation and triangle fractionation by precipitation from a solvent-nonsolvent mixture was carried out by adding alcohol to a dilute aqueous solution of the PSSHMA. Mw and [η] were measured by means of KMX-6 small angle laser light scattering spectroscopy and viscometry. Empirical correlation between intrinsic viscosity and molecular weight was obtained as follows [η] - 1.80×10-2 M0.68 The selection of fraction-ation condition for aqueous solution of PSSHMA polyelectrolyte and reasonable condition of measurement of light scattering and viscometry were also discussed.
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发布时间：2021-03-19 - 摘要：In this paper, the photodegradation of polyisoprene (PIP) with 9,10-dicyanoanthrace ne (DCA) as a photosensitizer has been studied. In the photodegradation process, it was found that the reaction proceeds according to the singlet oxygen mechanism. The DABCO-singlet oxygen quencher was used to quench 1O2. It was found that in the quenching process, the electron transfer between DABCO and DCA occured and the photostabilization of DABCO in the DCA-PIP system was promoted.
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发布时间：2021-03-19 - 摘要：The isothermal crystallization curves of polypropylene over a wide range of temperatures were obtained by the inverse gas chromatography. The calculated velocity constants are in accord with those derived by other methods. The experimental data have been treated with Avrami's equation the crystalline index n equals to 2.1. The crystallinity and the melting point of this polymer were studied. The crystallinity are influenced by experimental conditions and the thermal history of the sample. The melting points of both a-and β-form have been found by this method. In case there are two crystalline forms coexisted in one sample,a higher value of crystallinity is obtained as compared with that by other methods.
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发布时间：2021-03-19 - 摘要：A new molecular weight distribution is obtained when two samples of PET with different original molecular weight distribution are mixed and the polycondensation reaction occurs further under higher temperature. The values of mass fraction for n-mer have been calculated and plotted as a function of the degree of polymerization for several typical cases. The results have been discussed.
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发布时间：2021-03-19
Research Bulletin
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