Studies on Mechanical Denaturation of High Polymer Solutions IV. Effects of Degree of Polymerization and Tacticity of Syndiotacticity-rich Poly (Vinyl Alcohols) on Dissolution Temperature and Yield of Coagulation by Shearing Stress

• Published in: Kobunshi Kagaku Vol. 25; no. 273; pp. 55 - 61
• Main Authors: Go, Yukichi, Matsuzawa, Shuzi, Kondo, Yoshiyuki, Nakamura, Kazuo, Sakamoto, Toshio
• Format: Journal Article
• Language: Japanese
• Published: The Society of Polymer Science, Japan 25.01.1968
• ISSN: 0023-2556; 1884-8079
• DOI: 10.1295/koron1944.25.55

The effects of degree of polymerization and tacticity of syndiotacticity-rich poly (vinyl alcohols) on dissolution temperatures and yield of coagulation by shearing stress were studied. The syndiotacticity-rich PVA (VF-PVA) derived from poly (vinyl formate) polymerized at low temperatures and that (VTFA-PVA) derived from poly (vinyl trifluoroacetate) were used. In the case of VF-PVA, the lower the polymerization temperature of poly (vinyl formate) was, the higher its syndiotactic (diad)% was. In the case of VTFAPVA, the higher the degree of polymerization was, the lower its syndiotactic (diad)% was. It was found that the dissolution temperature of rough powder of VF-PVA and VTFAPVA were considerably higher than that of VAc-PVA. In the case of the samples with the same syndiotactic (diad)%, the higher the degree of polymerization was, the higher the dissolution temperature was. In the case of the samples of the same degree of polymerization, the higher the syndiotactic (diad)% was, the higher the dissolution temperature was. The dissolution temperature of the coagulations by shear obtained from an aqueous PVA solution was ca. 10°C higher than that of raw PVA. In the case of coagulations of the polymers having the same syndiotactic (diad)%, the higher the degree of polymerization of raw PVA was, the higher the dissolution temperature was. In the case of coagulations obtained from the raw PVA having the same degree of polymerization, the higher the dissolution temperature was, the higher the syndiotactic (diad)% was. The yield of coagulation from an aqueous VAc-PVA solution by shearing stress was little, but the yield of coagulation of VF-PVA was 8.9-40.7% and that of VTFA-PVA was 53.0-92.7. Syndiotactic (diad)% of coagulations was slightly higher than that of raw PVA. Thus, it is recognized that the sequence length of syndiotactic part plays an important role in the mechanical denaturation.