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本文由异成二烯-甲基丙烯酸甲酯共聚物的250兆赫氢-1核磁共振谱,定量地研究了共聚物中微结构单元及其组成。应用镨、铕两种位移试剂,通过观察1,4-异戊二烯双键质子峰的分离,测定了以1,4-戊戊二烯为中心的三元组分布,甚至五元组分布。确定了该体系的自由基共聚存在末前位效应,二级马尔克夫链模型的相应的竞聚率常数分别为:r_(II)=0.48,r_(MI)=0.86,r_(MM)=0.15,r_(IM)=0.43。以1,4-异戊二烯为中心的五元组分布和以甲基丙烯酸甲酯为中心的三元组分布的实验测定值与上述结果是一致的。
In this paper, the 250-mega hydrogen-1 nuclear magnetic resonance spectrum of isoprene-methyl methacrylate copolymer was used to quantitatively study the microstructure units and their compositions in the copolymer. The praseodymium and europium two shift reagents were used to determine the triplet distribution centering on 1,4-pentadiene by observing the proton peak separation of 1,4-isoprene double bond, and even the quintuple distribution . The results showed that there existed pre-penis effect in free radical copolymerization. The corresponding reactivity constant of second-order Markov chain model were: r_ (II) = 0.48, r_ (MI) = 0.86, r_ (MM) = 0.15 , r_ (IM) = 0.43. The experimental determinations of the 1,4-isoprene-centered pentad distribution and the methyl methacrylate-centered ternary distribution are consistent with the above results.