結晶性高分子のレオロジー
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概要
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The rheological properties of crystalline high polymers are discussed in contrast with those of amorphous polymers. The mixture of hard particles and amorphous polymer gives the simplest model of crystalline polymers. Some considerations in changes of structure of mixing state, gives a good interpretation for the change of Young's modulus with increasing crystallinity by this simple mixture model. Although this approach can not give the interpretations of time-dependent phenomena, the author believes that this simple model has still some possibility of progresses. The time dependent mechanical properties of high polymers must be expressed as a function of time and temperature. The most elabolate method, which measures the dynamical properties as a function of both time and temperature is developed by Fitzgerald. Very recently, it is revealed by Fitzgerald's transducer, that the crystalline polymers show some resonance-type dispersions at audio frequencies. This phenomenon has an important meaning which connects the polymer rheology with dislocation theory of crystal plasticity. Relations between mechanical loss factor and temperature under nearly constant frequency for various crystalline polymers are obtained by Schmieder and many other researchers. On the contrary, the measurement under constant temperature and variable frequencies need a high technique. Fujino and Kawai, and Tokita have measured the mechanical responses of several crystalline polymers covering six decade of frequencies by the use of several different apparatus. The time-temperature reduction method, which has played an important role in the progress of rheology of amorphous polymers, is found to be also applicable for crystalline polymers. By the application of reduction method and of its modification by Takemura, the author and his coworkers have succeeded to determine the relaxation time spectra of Nylon-6, Teflon, Kel-F and Polyethylene over a wide range of relaxation time. As is seen in Fig. 3, these spectra for crystalline polymers seem to have some common features. And it is found that these spectra give successful interpretation for many of rheological properties of crystalline polymers. The investigations of non-linear behavior, and mechanical properties of anisotropic polymers, which are most interesting for crystalline polymer, will need more accumulations of systematic experimental works not only by rheological methods but also by colaboration of structure analysis, dielectric and NMR measurements.
- 社団法人日本材料学会の論文
- 1959-04-15