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

✍ Scribed by Kazuomi Agawa; Qui Wan; Tetsuya Tanigami; Shuji Matsuzawa; Kazuo Yamaura

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 236 KB
• Volume: 80
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/1097-4628(20010418)80:3<467::aid-app1120>3.0.co;2-e

✦ Synopsis

The structure and properties of syndiotacticity-rich poly(vinyl alcohol) (s-PVA) prepared through the saponification of drawn poly(vinyl trifluoroacetate) (PVT-FAc) 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 Ϫ1 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 Ϫ1 in the infrared spectra of the saponified samples was weak.