非均相混合溶剂法制备高缩醛度PVAc的影响因素

针对目前非均相水溶剂法合成聚乙烯醇缩乙醛(PVAc)缩醛度低的问题,在水相法基础上,采用非均相混合溶剂法合成了高缩醛度PVAc,研究了乙醛加入量、盐酸加入量、析出温度、溶剂加入量对缩醛度及产品收率的影响。结果表明:采用非均相混合溶剂法合成的PVAc缩醛度较传统非均相水溶剂法有明显提升。采用响应面法对缩醛度和产品收率进行了综合优化,当析出温度为11.8℃,乙醛与聚乙烯醇摩尔比为0.46,乙醇质量分数为12.2%时,缩醛度最佳,达86.3%。

Influential factors of preparation of high acetal degree PVAc via heterogeneous mixed solvent method

High acetal degree poly(vinyl acetate)(PVAc)was prepared via heterogeneous mixed solvent method based on aqueous phase method to resolve the issue of low acetal degree PVAc from traditional methods.The effects of precipitation temperature,the amount of acetaldehyde,hydrochloric acid,and the solvent on the acetal degree and the yield of the product were observed.The results show that the acetal degree in PVAc synthesized by water-organic mixed solvent method is significantly higher than that of the traditional aqueous phase method.The degree of acetaldehyde and the product yield are comprehensively optimized by response surface method.The acetal degree reaches the highest of 86.3%when the precipitation temperature is 11.8℃.The molar ratio of acetaldehyde and polyvinyl alcohol is 0.46,and the mass fraction of ethanol is 12.2%.