Structural Analysis of Poly(p-phenylene terephthalamide) Films from Liquid Crystalline Solutions.

MIYASHITA Norikazu, NAKAO Tatsuya, FUJITA Tadahiro, FUJIWARA Takashi, AMANO Toshihiko

doi:10.1295/koron.51.745

Poly (p-phenylene terephthalamide) (PPTA) films were formed from a liquid crystalline sulphuric acid solution using water as a coagulant. The polymer dope with optical anisotropy was cast on a flat plate. The phase transition from the optical anisotropy to isotropy was accomplished by means of controlling temperature and humidity, and then the cast dope was immersed in a coagulation bath. When the film was dried at room temperature after the coagulation without any dimensinal restrictions, crytallites in the film were randomly oriented. The (010) reflection of the type II modification of the PPTA crystal was hardly found in the X-ray diagram of the film. When the drying at room temperature was carried out with constant dimensions, the film showed the (0k0) planar orientation of the type II crystal. If the film was annealed at higher temperatures, the II crystal was transformed to the type I crystal and the film orientation changed at the same time towards the (h00) planar orientation. A never-dried film exhibited very low crystallinity and random orientation. The drying process with dimensional restrictions proves to be an important factor in both generating the type II crystal and forming the planar orientation.

Structural Analysis of Poly(p-phenylene terephthalamide) Films from Liquid Crystalline Solutions.

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