摘要
在50、60、70、80℃下,聚合醋酸乙烯酯(VAc)制得一系列聚醋酸乙烯酯(PVAc),并在氢氧化钠作用下醇解制得聚乙烯醇(PVA);通过黏度法测定聚乙烯醇被高碘酸钾降解前后的相对分子质量,从而计算出聚乙烯醇中"头碰头"的键合几率;然后聚乙烯醇与甲醛在酸催化作用下制备聚乙烯醇缩甲醛,并计算出聚乙烯醇缩甲醛的缩醛度;最后得出聚合温度对聚乙烯醇键合方式和聚乙烯醇缩甲醛缩醛度的影响。实验结果表明:聚合温度低,聚乙烯醇的聚合度大、相对分子质量大、黏度大,而且聚乙烯醇分子中"头碰头"键合几率小,最佳的聚合温度是60℃;聚乙烯醇缩甲醛的缩醛度则随着聚合温度的升高而降低。
Polyvinyl acetate （PVAc） with different molecular weight were prepared by solution polymerization at 50,60, 70,80 ℃. And polyvinyl alcohol （PVA） was prepared by methanolysis of the PVAc in sodium hydroxide. The molecular weight of the PVA was determined by the viscosity method. And the PVA was decomposed by potassium periodate. Then the molecular weight of the decomposed product was determined by using the same method. The frequency of the head-to- head linkages in PVA was calculated. Then, polyvinyl formal was prepared by the reaction of PVA and formaldehyde under the catalysis of acidity. The acetyl degree of polyvinyl formal were calculated. Finally, the frequency of the head-to- head linkages in PVA and the acetyl degree of polyvinyl formal which was influenced by the polymerization temperature were summarized. The experimental results showed that the bigger molecular weight and the lower frequency of head-to- head linkages in PVA with lower polymerization temperature was prepared; the best polymerization temperature was 60℃ ; the acetyl degree of polyvinyl formal decreased with increasing polymerization temperature.
出处
《实验室研究与探索》
CAS
北大核心
2011年第11期26-28,共3页
Research and Exploration In Laboratory
关键词
聚乙烯醇
键合方式
黏度法
缩醛度
polyvinyl alcohol
chain linkage
polymerization temperature
viscosity method
acetyl degree
