最新刊期
卷 ， 期 4 ， 1986
- 摘要：The stress-strain behavior of mainly β-form of isotactic polypropylene was measured at various temperatures and compared with those of α-form of the same grade sample. The results show that β-form sample has a lower yield strength and a higher impact strength than that of the α-form. The change of crystalline structure during stretching was studied by X-ray differaction technique. The difference in mechanical behavior of α- and β-forms was explained qualitatively with molecular model of deformation and structure transformation during strecting.
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发布时间：2021-03-19 - 摘要：Structural change in an unoriented, amorphous PET film annealed at temperatures below T, and the effect of ezcess enthalpy relaxation on oermeation rates of CO2 gas and toluene liquid in treated samples have been studied. The results suggest that the amount of excess enthalpy relaxation as determined from the endothermic peak in T, interval, the Tg and density all increase with annealing time, but the trans-conformation component of samples decreases. No change of structure in the amorphous phase was found other than the normal densification of the molecular chain packing or a reduc-tion in free volume had occurred during the annealing. Therefore,the permeation rte of CO2 gas in treated samples reduced. While the apparent permation rate of toluene liquid increased with annealing time because ofacreation of extensive cracks at film surface arising from both the increase in embrittlement of polymer and the swelling action of toluene liquid on treated samples.
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发布时间：2021-03-19 - 摘要：Cis-1, 4-polybutadiene synthesized by lanthanide catalyst (Ln-PB) was fractionated by precipitation method (toluene/methanol) into 5 fractions. Crystallization of each fraction was carried out at -30℃ and its morphological structure was investigated by transmisson electron microscopy. The structure parameters of entanglement network were obtanied from experimental relaxation spectrum. It has been found that the morphology and rate of crystallization depend not only on the stereoregularity, but also on the molecular weight and molecular weight fraction crystallized primarily with predetermined nuclei,and its lamellae are not entangled,while the high molecular weight fraction crystallized primarily from sporadic nuclei,and accompanied by lamellae entanglement. The nu-claetion and growth of crystallization depend on the average molecular weight of entang-lement segment Me.
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发布时间：2021-03-19 - 摘要：Flowable polysilane polymers have been synthesized by sodium coupling of diorgano-dichlorosilanes with diphenylmethylchlorosilane in toluene. These polysilanes can be formed into desired shape by potting, casting or coating and crosslinked by ultraviolet irradiation in the presence of multifunctional vinylsilanes. The molecular weight distributions, infra-red, ultraviolet and nuclear magnetic resonance spectra for the polysilane polymers have been described.
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发布时间：2021-03-19 - 摘要：The charge-accumulating process of polymeric photoconductive coating film for use in electrophotography, as well as factors controlling the charging rate, have been studied, and the characterization method of charging process and kinetic equations have been established.
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发布时间：2021-03-19 - 摘要：In this paper, we reported that peroxy fluorine containing radicals were slowly decayed, and existed for a long time at room temper ture. The effective period of preir-radiation was over 6 years. Influences of temperature, inorganic additives and organic-solvents on styrene graft reaction has been investigation. The percentage of grafting increased with the lowering of he reaction temperature, and the homoplymerization of styrene can be effectively inhilited by adding ferric chloride in styrene during the graft reaction. The structural characteristics of polychlorotrifluoroethylene-styrene copolymer were also studied.
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发布时间：2021-03-19 - 摘要：Drawn commercial yarns of poly ethylene terephthalate (PET) multifilament were heat treated (secondary setting) by infra red heat source on a three-factor heat-treat equipment made by our laboratory. By means of wide-angle X-ray Diffraction (WAXS), Small-Angle X-ray Scattering (SAXS) and IB Specfcroscopy, heat shrinkage, crystallinity, crystallite orientation and size, non-crystalline orientation, long period and regular folded conformation band intensity of the treated yarns were measured. The change of these structural parameters showed that the tension was not able to preventmolecular chain refolding above 200℃ . Under constant tension treatment a critical value of tension fcritical=0.066 g/dtex was found,above which the tension will prevent chain refolding.
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发布时间：2021-03-19 - 摘要：The present paper demonstrates that every pair of unreacted groups in the cross-linked network loss a canstant of 3 for the number of effective segment in the curing reaction which produces three branch cross-linking point. The cross-link density of ∑Aai-∑Bbi type curing reaction is a function of the functional density, the effective number average functionality, the ratio of number of curing agent groups to prepolymer reactive groups, the gel fraction of curing system, the extent of reaction of A (or B) groups in gel phase and the gel fraction of Aai (or Bbi)segment The last two parame-ters can not be determined directly,but can be calculated by determining the sol fra-ction and the extent of reaction of A groups and Bgroupsin sol phase.
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发布时间：2021-03-19 - 摘要：In this paper the experimental results measured continuously on the gaseous products of high temperature pyrolysis (300℃ to 960℃) of acrylonitrile polymers were described under given nitrogen atmosphere by on-line Fourier Transform Infrared Spec-troscopic method (FTIR). From the variations of intensity of characteristic peaks it was found that the nitrogen, of macromolecules evolved were mainly in the form of hydrogen cyanide and ammonia. During the pyrolysis amorphous carbonaceous element was formed, and crosslinked to form a network structure. Three samples were used for comparison. The experimental results show that the gaseous products of volatile small molecules were HCN,NH3,CH4,C2H6and cyanide,CO and CO2 were formed when co-polymer of PAN were thermally pyrolyzed.
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发布时间：2021-03-19
Research Article
- 摘要：High performance GPC is a powerful technique for polymer characterization, but the mechanical degradation is expected to be serious in this case. We have to consider the degradation of the high-molecular-weight portion of the sample after passing through high performance GPC column. From the result obtained we can conclude that six P2VP samples, after passage through GPC columns, showed serious degradation (64%), therefore high performance GPC can not be used as a method of determining molecular weight and molecular weight distribution of high-molecular-weight P2VP(M>2.66×10-6).
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发布时间：2021-03-19 - 摘要：The gaseous condensates in the process of plasma polymerization of hexafluoropro-pylene were analysed by means of ESR and GC-MS, ESR signal with a hyperfine structure of 20 splitted lines was observed at room temperature. The variation of the ESR with temperature from - 160℃ to 150℃ was also studied. The existance of very stable free radicals in the gaseous condensate is indicated by the fact that the ESR signal still persist even after the condensates has been exposed to the air at ambient temperature for three months. From the results of the GC-MS and ESR data,free radical reaction mechanism was deduced for the plasma polymerization of hexafluoropropylene.
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发布时间：2021-03-19 - 摘要：Rheological measurements for PP melts with different M & MWD have been made in a capillary rheometer with length/diameter ratio 0, 6.4, 40, 100 as well as in cone/ plate and falling sphere viscometers. Melt transition in entrance converging flow was observed under about 208℃ which causes the increase of flow drag. The successive capillary could eliminate this structuring effect. This phenomenon was not observed in pure shear flow which should be distinguished from the stress induced crystallization of melt.A mechanism was suggested b assuming the existence of week mesomorphic state under 208℃ which can be strengthened in converging flow.
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发布时间：2021-03-19 - 摘要：The gas condensates from polymerization of TFE in glow discharge have been investigated by means of ESR and GC-MS, and the mechanism of plasma polymerization is proposed herefrom. ESR signal with a hyperfine structure of about 160 splitted lines was observed for the gas condensates. It has also been found that the gas condensates contain some linear chain and low molecular weight perfluoroalkanes and perfluo-rocyeloalkanes.
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发布时间：2021-03-19 - 摘要：The catalytic behaviour of tetravalent molybdenum catalyst system in the polymerization of dutadiene has been studied. The ca.talyst system is highly active when anions that combined with molybdenum are carboxylic acid group (BCOO-) or alkoxy (-OR) group. Obviously, the variety of substituent R in (i-Bu)2AlOR has great influence on the catalytic activity. The system is inactive, if the R group is carboxylic acid or alkoxy, while the activity of catalyst system increases if the R group is phenyl or tolyl. The content of 1,2-unit and the molecular weight of polymer decreases while the destri-bution index increases as polymerization temperature rises.
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发布时间：2021-03-19 - 摘要：In this paper, studies on the kinetic of polymerization of triethyltin methacrylate (TETM) in benzene solution at 60-80℃ in the presence of azobisisobutyronitrile (AIBM) were reported. It was shown that the rate equation of polymerization could be expressed as follows:Bp = Kp [TBTM]1.5 [AIBN]0.5,where [AIBN] and [TBTM] were the concentrations of the initiator and the monomer, respectively. The action energy of polymerization was found to be 16.6 kcal/mol.
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发布时间：2021-03-19
Research Bulletin
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