科研之友
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摘要
Multi-scales relaxation processes of short fiber of a nematic liquid crystalline copolymer (LCP) in polycarbonate matrix were investigated. First, the structure relaxation of LCP was studied by rheology. The relaxation spectrum of the nematic liquid crystalline copolymer at 295 C was calculated from the combined dynamic modulus. There are three kinds of relaxation mechanisms for nematic liquid crystalline copolymer: the relaxation of chain orientation, the relaxation of deformed polydomains and the coalescence of polydomains (or the relaxation of textures). As the relaxation of chain orientation is very fast, we have not obtained the accurate relaxation time by rheological measurements. The relaxation of deformed polydomains takes about 50 s. Domain coalescence occurs after a much longer relaxation time (> 2400 s). Secondly, the shape relaxation of LCP short fiber in matrix was studied. During shape relaxation of short fiber in matrix, changes of inner structure in short fiber take place, which is characterized by the application of power spectrum of discrete Fourier transform (DFT). The aspect ratio b/a increases during shape relaxation of short fiber in matrix.
