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首页> 外文期刊>Macromolecular symposia >Quantitative NMR Spectroscopy and Determination of Polymer Microstructure of Ethylene-Styrene and Ethylene-Isobutylene Co-Polymers
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Quantitative NMR Spectroscopy and Determination of Polymer Microstructure of Ethylene-Styrene and Ethylene-Isobutylene Co-Polymers

机译：乙烯-苯乙烯和乙烯-异丁烯共聚聚合物的定量NMR光谱和聚合物微结构的测定

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摘要

Quantitative ~(13)C NMR spectroscopy is used to determine reactivity ratios and end group and branching frequency of ethylene-styrene and ethylene-isobutylene co-polymers synthesized at a temperature T=205 °C and pressure p=1650 bar at different levels of co-monomer fraction. In the forefront of the studies quantitative ~(13)C NMR conditions have to be investigated. Optimum conditions are achieved using a relaxation agent Chromium(III) acetylacetonate (Cr(acac)3) at measurement temperature T=100 °C and a delay time d_1=7 s with a 90° pulse and inverse-gated decoupling. The analysis of conversion dependence of co-monomer content shows an increase in conversion with increasing co-monomer content for the ethylenestyrene co-polymerization, whereas conversion decreases with rising isobutene fraction in the co-polymer. Reactivity ratios for ethylene-styrene as well as for ethylene-isobutylene co-polymerization system are determined with values r_(ES)=0.09±0.007 and r_(SE)=2.3±7.0 and r_(EIB)=3.3±0.6 and r_(IBE)=6.3±4.2. Frequency on methyl end groups, end-of-chain contributions caused by transfer to propionic aldehyde and butyl branches are gained. For the ethylene-styrene copolymer system a decrease in frequency is observed, whereas for the ethyleneisobutylene co-polymer system the opposite occurs. Influence of the co-monomers on the polymerization reaction steps as transfer to chain transfer agent and backbiting reaction is discussed.
机译：〜（13）C NMR定量光谱用于确定在T = 205°C和p = 1650 bar的压力下合成的乙烯-苯乙烯和乙烯-异丁烯共聚物的反应率，端基和支化频率。共聚单体分数。在研究的最前沿，必须研究定量〜（13）C NMR条件。使用松弛剂乙酰丙酮铬（III）（Cr（acac）3）在测量温度T = 100°C和延迟时间d_1 = 7 s（具有90°脉冲和反向选通的去耦）下可获得最佳条件。对共聚单体含量的转化率依赖性的分析显示，对于乙烯苯乙烯共聚，共聚单体含量的转化率增加，而随着共聚物中异丁烯含量的增加，转化率降低。乙烯-苯乙烯以及乙烯-异丁烯共聚体系的反应比确定为r_（ES）= 0.09±0.007和r_（SE）= 2.3±7.0以及r_（EIB）= 3.3±0.6和r_（ IBE）= 6.3±4.2。获得甲基端基的频率，由于转移至丙醛和丁基支链而引起的链端贡献。对于乙烯-苯乙烯共聚物体系，观察到频率降低，而对于乙烯-异丁烯共聚物体系，则相反。讨论了共聚单体对聚合反应步骤的影响，如转移至链转移剂和回位反应。

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