Synthesis of High Molecular Weight PVA and Preparation of High Performance Materials.

点击翻译按钮获取中文摘要

Preparation of high molecular weight PVA and its film and fiber were successfully developed by help of the grant for last 2 years as following.PVA of Pn=13000 was obtained through photo-emulsion polymerization of vinyl acetate(VAc) in the absence of initiator at OﾟC. Pn=18000 was attained through polymerization of vinyl pivalate(VP) by the same manner. Saponification of poly(vinyl pivalate)(PVP) was very difficult, but we found a good method to saponify it. High molecular weight PVAs were obtained through co-polymerizations of VAc and VP by the same manner.The ratios of syndiotactic diad(SD) of PVAs from PVAc and PVP were 53% and 64%, respectively. The SD% of PVA from co-polymer increased from 53% to 64% with increasing feed VP concentration. The SD value(64%) is largest and the PVA is expected to have interesting reactivity and physical properties. Moreover, PVA of controlled tacticity obtained through copolymerization is expected to clear relationship between tacticity and reactivity or physical properties.Tm(crystal melting temp.) of a film prepared from PVA(SD=64%) was higher than that from PVA (SD=53%) by 20 degree. PVA(SD=53%) film showed high separation factor(alpha=3000) for pervaporation of isopropanol aq. solution. PVA(SD=53%) fiber spun from its gel showed high strength. From the results we believe that these PVAs are useful in many fields.