Fine Structures and Phase Transitions in Polyorganophosphazene

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We have investigated the following subjects at this International Scientific Research Program in two years.(1) Structural studies on annealing effects of poly[bis(p-fluorophenoxy)phosphazene] and poly[bis(p-chlorophenoxy)phosphazene] associated with polymorphism. These annealing effects are only observed in the temperature range higher than T(1) transition. In this study, we have determined the lattice constants of poly[bis(p-fluorophenoxy)phosphazene]. (2) Kinetic studies on transformations from the 2D meso state to the 3D crystalline state in various kinds of polyorganophosphazene ( sample thickness dependence or nucleation effects ). (3) Preparation of single crystals of poly[bis(p-methylphenoxy)phosphazene] and poly[bis(p-methylphenoxy)phosphazene and determination of their lattice constants by electron diffraction techniques. (4) Examinations of phase transitions in polyphosphazeness by an ultra sonic absorption method. Sonic velocity changes and absorption intensity changes have clearly been detected at 170 C in the T(1) range.Two subjects of these cooperative studies, (2) and (4), will be continued further in the next year. In this cooperation, wide varieties of mutual understandings between Japan and the United States have been experienced. We appreciate very much the Ministry of Education, who gave the chance to execute the International Research Program.