核磁共振法测定EVA中的VA含量和序列结构

摘要

The vinyl acetate(VA)in ethylene-vinyl acetate(EVA)resin is determined by nuclear magnetic resonance(NMR)method. The samples of EVA resin were tested respectively by high temperature proton and carbon nuclear magnetic resonance(1H-NMR and13C-NMR)spectrometry to establish the analytical method for accurate determination of VA content in EVA via1H-NMR. This method is accurate, reliable, simple and easily operated. The diad and triad monomer sequence structure in EVA resin were calculated by13C-NMR. The results show that the probability of self propagation of free radical of VA and ethylene monomers in polymerization process is equal to that of cross propagation, which represents a typical system of ideal copolymerization.%采用核磁共振法测定了乙烯-乙酸乙烯酯共聚物(EVA)中乙酸乙烯酯(VA)含量,通过对EVA高温核磁共振氢谱和核磁共振碳谱的测试分析,建立了利用核磁共振氢谱法测定EVA中VA含量的方法,该方法准确、可靠、简单、易于操作.利用核磁共振碳谱法计算了EVA的二单元和三单元序列结构含量,结果表明:EVA中VA单体和乙烯单体在聚合过程中自由基的自增长和交叉增长的概率大致相同,该体系是典型的理想共聚体系.