丙烯腈与丙烯酸乙酯乳液共聚合及其表征

用氧化还原引发体系在低温下研究了丙烯腈与丙烯酸乙酯的乳液共聚合。考察了聚合温度、乳化剂浓度和分子量调节剂浓度对聚合的影响 ,结果表明 ,随温度升高 ,乳化剂浓度增大 ,单体转化率和分子量增大 ,乳液更稳定 ;链转移剂十二烷基硫醇浓度增加 ,分子量显著降低 ,转化率有所降低 ,表明十二烷基硫醇在调节分子量的同时也起着缓聚剂的作用。用激光粒径分析仪考察了 2 0℃时聚合过程中乳胶粒子大小的变化 ,发现聚合过程的成核和增长均在胶束中进行的。用凝胶渗透色谱法研究了十二烷基硫醇对聚合物分子量的影响 ,发现聚合时加入分子量调节剂 ,活性链寿命较短并呈单峰分布 :聚合时不加入分子量调节剂 ,活性链寿命较长并呈双峰分布。 DSC结果表明 ,随聚合体系中软单体含量增加 ,共聚物的玻璃化温度降低。

Emulsion Copolymerization on Acrylonitrile and Ethylacrylate and Characterization

The emulsion copolymerization of acrylonitrile and ethylacrylate with a redox initiator system potassium persulfate/sodium bisulfite at low temperature was researched. The effects of temperature, emulsifier concentration and chain transfer agent concentration on polymerization results were investigated. The results shows that, with increasing emulsifier concentration and elevating temperature, the monomer conversion and molecular weight increased, and the latex was more stable.With increasing the concentration of n-dedocyl mercaptan, the molecular weight sharply reduced and monomer conversion lowered. The results indicated that n-dedocyl mercaptan played twofold roles, one was the chain transfer agent, the other was themoderator for polymerization. The change of latex particle size in the course of polymerization at 20℃ was investigated with laser particle size analysis. It inferred that the nucleation and propagation all carried out inside micelle. The effects of n-dedocyl mercaptan on molecular weight were investigated with geipenetration chromospectrum. The results shown that the average life-time of active chain was shorter and the distribution of molecular weight was in one-peak mold when n-dedocyl mercaptan was added into polymerization system, and the life-time of active chain varied more seriously and the distribution of molecular weight was in two-peak mold when not adding n-dedocyl mercaptan into polymerization system. The results of analysis to copolymers with differential scanning calorimeter indicated that, with increasing the content of soft monomer, the glass temperature of copolymer lowered.