Novel Spherulitic Structures of Polyorganophosphazenes in Relation to Their Polymorphism

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Crystallizable polyorganophosphazenes (POP) have so-called T (1) transitions at which the polymer changes from its 3-D crystalline state to the 3-D mesomorphic structre (the delta phase). The transition generally locates between the glass transition temperature and the melting point. In this research, isothermal crystallization kinetics of two types of polyphosphazenes from their delta phase have been invesigated, and resultant spherulitic structures of POP's are examined in terms of their polymorphism mainly by optical microscopy, high temperature x-ray diffraction and thermal analysis. The results obtained are summarized as follows :(1)When the poly [bis (3,4-dimethylphenoxy) phosphazene] (PB (dM) PP)films heated at 140ﾟC were cooled down to various isothermal temperatures, T_c, A-type spherulites (more than 100mum in diameter) and B-type spherulites sppeared independently. According to relative amount of the two types of spherulites in the sample, the T_c range can be divided into three regions.The relationship between the types of PB (dM) PP spherulite and its crystal forms was examined in detail using x-ray diffraction. The A-type spherulite is composed of the alpha-form crystal (Pbcn) and the B-type spherulites of the beta-form (also orthorhombic).(3) We tried to identify the direction of the c axis located in the B-type spherulite using polarized infrared spectra of the sample, but failed to determine the exact direction, since the polarlzed infrared spectra indicated were the same characteristics between the direction paralell to the spherulite radius and that vertival to it. These findings require more x-ray diffraction data by microbeam experiments. The works along this linewill be continued in future.(4) Morpholigocal features of poly [bis (4-ethylphenoxy) phosphazene] were also investigated in a similar manner as those for PB (dM) PP,and the results showed considerably diffrent crystallization mechanism from that of PB (dM) PP.