摘要
用负载偏钒酸根的强碱性阴离子交换树脂(PV)与硫脲(TU)组成氧化还原体系在硝酸溶液中引发丙烯腈(AN)聚合,表观聚合速度是: R=1.92×10~4e^(-6860)/RT[AN]^(1.2)[RV]^(0.44)[TU]^(1.8)[HNO_ 3]^(1.0)聚合动力学参数与V^(6+)—TU体系所得者不同,表明初级自由基的产生受扩散控制因素的重要影响,并且载体树脂在聚合过程中存在着强烈的大分子场效应。聚合诱导期(ι)与引发速度成反比。聚合物分子量与聚合速度成正比,与终止速度和聚合温度成反比。加料方式实验再一次表明了引发种是由五价钒和硫脲络合和/或缔合所产生而不是和异硫脲结合的结果。本文讨论了引发聚合机理。
The polymerization of acrylonitrile (AN) is initiated by pentavalent vanadium containing anion exchanger (PV)-thiourea (TU) redox system. The overall rate of polymerization (R) is obtained: R_p =1.92×10~4e^-6860' [AN]~1.2[pv]~0.44[TU]~1.0 [HNO_3]~1.0 The kinetic parameters of polymerization differ from those of V^(5+)-TU system. It suggests that the generation of the primary radicals is mainly a diffusion controlled reaction, the effect of macromolecular field arisen from the polymer supporter is present and exerts a great influence on the polymerization. too. the length of the induction period of polymerization (τ) is inversely proportional to the rate of initiation. The molecular weights of polymer are directly proportional to the rate of polymerization and inversely proportional to the rate of termination and the temperature of polymerization. The rate of polymerization has become more slow when the isothiourea is used instead of the thiourea as an initiator. It indicates that the active complexes are generated from the pentavalent vanadium coordinated and/or associated with thiourea rather than isothiourea. The polymerization mechanism was discussed on the basis of the experimental results obtained.
出处
《广州化学》
CAS
1990年第1期19-30,共12页
Guangzhou Chemistry
