最新刊期
      卷 ， 期 3 ， 1979

        Research Article

      • XU Zhen-miao,CHEN Shou-xi
        Issue 3, Pages: 129-134(1979)
        摘要：An instrument for determining the rate of crystallization of polymer from melt by depolarized light intensity method is described, and satisfactory results were obtained for isotactic polypropylene and nylon 6 samples. This method possesses following advantages: (1) only a small amount of sample is needed; (2) the crystallization rate of (t1/2) not less than about 40 sec. can be me asured. Reliable and reproducible results can be obtained by the use of an automatic control circuit to supply a constant light intensity through the sample cell.  
          
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      • SHEN De-yan,Zhu Li-Ian
        Issue 3, Pages: 135-140(1979)
        摘要：A series of copolymers of acrylonitrile and vinyl acetate with different composi-tion has been synthesized．Their IR etra have been compared with those of eorres．ponding mixtures of polyaerylonitrile and polyvinyl acetate．Quite distinct differences are found between the IR spectra of copolymers and corresponding mixtures．Such ldnd of differenee is explained in view of the interaction between the adjacent units within a copolymer molecule．Based on the previous observation，the sequence distribution of acrylonitrile units in aerylonitrile-vinyl acetate copolymers has been measured with the shift of nitrile stretching vibration band．The composition relation of copolymers has been measured with the absorbance ratio of carbo*nyl stretching vibration band and nitrile stretching vibration band．The error of these measurements in a quite wide range of copolymer composition is estimated to be less than 3％．  
          
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      • Pan Dao-cheng,Xia Gen-lin
        Issue 3, Pages: 141-148(1979)
        摘要：The thermal imidation of fluorine-containing poly(amide-acid)has been investiga-ted by Tarsional Braid Analysis(TBA)．The results are discussed in tems of the molecular motion of polymer segments above its glass transition temperature，which is favourable to the diffusion vf small molecules and，therefore，has effect on the imidation reaction．The glass transition temperature increased from 120℃ to about 310℃ with in-creasing rigidity of the polymer chain by imidation reaction．Hence a reason,able productiun process of step-up cure is suggested．The multiple transitions including solvent evaporation，glass transition，secondary transition in glassy state and imMation reaction of pre-polymer in the TBA Spectra have been analyzed．The effect of solvent and water on imidation reactivn has been observed and explained with the above viewpoint．  
          
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      • QIAN Bao-jun
        Issue 3, Pages: 149-159(1979)
        摘要：The meaning and aim of thermo-mechanical analysis are explained. The basic principle of the construction of the thermo-mechanical analyser developed in our laboratory is described briefly. With this instrument, we can, during a programmed temperature rise, measure the length changes of the fibre under a fixed tension, the stress changes in the fibre under fixed length or the stress-strain relationship when both quantities vary. Finally, the transition temperatures of acrylic fibres are estimated from characteristic curves,obtained by thermo-mechanical analysis, followed by a short discussion of the nature of these transitions.  
          
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      • Tan De-yue
        Issue 3, Pages: 160-172(1979)
        摘要：This paper deals with the molecular weight distribution of the living polymer generated by bi-functional initiator of which the initiation rate constants of both reactive groups are different in each other. The expressions of the molecular weight distribution function and the average degrees of polymerization have been derived, and four special cases were discussed.  
          
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      • Issue 3, Pages: 173-184(1979)
        摘要：The mechanism of solution polyeondensation of MDl with TMA was preliminarily studied with model compound．by means of Semi-quantitative analysis of infra-red spectroscopy and viscosity．It is found that the polycondensation is an irreversible reaction and its important charaeteristic is that amido and imido groups are formed at the flame time．The viscosity of the solution increases with the increasing of MDI in excess and eventually gel,ation takes place． All the solvents which contain actire hydrogen or unshared electrons are not suitable for this reaction due to the possibi-1ity of addition reaetion with MDI．When the water content of the solvent used is over 0.16％，the polycondensation reaction can not normally proceed．Because of the absence of labile polyamide-acid and only CO2 evolving during the polyeondensation，the storage stability of the condensation solution shows good．The high temperature treatment of the polycondensate induces the further com-pletion of imidezation and changing of the structure of molecular aggregation，and thus causes the molecular weight to increase continuously．The additiun of a certain amount of epoxide resin of low molecular weight into the polyconsation system not only reduces the fabrication temperature of the PAI about 80℃。but also improves both the property of film formed and its storage stability．  
          
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