Structure and properties of syndiotacticity-rich poly(vinyl alcohol) prepared through saponification of drawn poly(vinyl trifluoroacetate) with gaseous ammonia

Abstract

The structure and properties of syndiotacticity-rich poly(vinyl alcohol) (s-PVA) prepared through the saponification of drawn poly(vinyl trifluoroacetate) (PVTFAc) with gaseous ammonia were studied. The PVTFAc samples with s-diad % of 59 and 64 were used. The s-PVAs had low densities and showed X-ray diagrams similar to the fiber diagram of PVA with indistinct 100, 101, 101, and 200 plane reflections and without the plane reflections seen at the equator of a typical fiber diagram, such as 001, 201, and 002. The s-PVAs had melting points comparable to those of saponified and heat-drawn samples, indicating a PVA with the typical fiber structure as seen in the X-ray diagram of a sample. The intensity of the 916 cm 1 band in the infrared spectrum related to syndiotactic diads decreased with drawing, suggesting an increase in the crystallinity. Crystals with more defects are thought to be produced in saponification. The s-PVA films drawn 16 times and saponified had a Young's modulus and strength at break of 22 and 1.5 GPa for the sample from S-59 and 14 and 1.2 GPa for the sample from S-64, respectively. The crystallization-sensitive band of 1145 cm 1 in the infrared spectra of the saponified samples was weak.