乙烯醇
醋酸乙烯酯
战术性
高分子化学
聚合
结晶度
乙烯基聚合物
聚合物
溶解
材料科学
溶剂
化学工程
化学
有机化学
共聚物
复合材料
工程类
作者
H. N. Friedlander,Henry E. Harris,Jane Pritchard
出处
期刊:Journal of polymer science
[Wiley]
日期:1966-03-01
卷期号:4 (3): 649-664
被引量:42
标识
DOI:10.1002/pol.1966.150040319
摘要
The solubility properties of poly(vinyl alcohol) (PVA) vary with the method of preparation of the poly(vinyl acetate) (PVAc) from which it is derived. PVAc was prepared with free-radical catalysts over a range of temperatures from −78 to 90°C. with solvents of varying chain-transfer ability. The corresponding PVA samples varied in their resistance to dissolution in water. Their high-resolution proton nuclear magnetic resonance spectra showed on differences in tacticity. Data on 1,2-diol content showed only minor differences. Hence, the increase in resistance of PVA to dissolution in water arising from changes in chain-transfer activity of the solvent used in vinyl acetate polymerization is largely attributable to a decrease in molecular weight, and the increase in resistance of PVA to dissolution in water arising from a decrease in the temperature of the vinyl acetate polymerization is largely attributable to a decrease in both long and short branches. Evidently, with polar polymers having small side groups, tacticity is not the only factor influencing property variation; that is, variations in stereoregularity influence more the crystallinity of the sample as measured by density or x-ray methods than the ultimate crystallizability under conditions of mechanical and thermal treatment. In this regard polar polymers having small side groups differ from nonpolar polymers.
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