氯丁胶乳乳液接枝甲基丙烯酸甲酯反应动力学

Kinetics of Grafting Polymerization of Chloroprene Latex with Methyl Methacrylate by Emulsion Polymerization

采用乳液聚合法将甲基丙烯酸甲酯(MMA)接枝到氯丁胶乳上,红外光谱和核磁共振氢谱证实了接枝产物的生成。研究了反应温度、乳化剂浓度、引发剂浓度和单体浓度对表观聚合速率的影响。结果表明,当反应温度为50℃,引发剂叔丁基过氧化氢-四乙烯五胺(t-BHP/TEPA)用量为氯丁胶乳干重的0.5%,单体/聚合物质量比m(M):m(P)=3:5,乳化剂十二烷基连苯醚二磺酸钠(DSB)用量为单体总质量1%时,单体转化率和接枝效率分别为99.1%和54.9%。聚合反应动力学关系式为:Rp=Kc(E)0.15c(I)0.30c(MMA)1.41,式中,K为常数,在40～55℃范围内,聚合反应的表观活化能Ea=60.2kJ/mol。接枝聚合基本符合自由基反应机理。

Grafting of methyl methacrylate （MMA） onto chloroprene latex was carried out by emulsion polymerization.FTIR and 1H NMR confirmed that the grafted polymer was formed.Effects of the reaction temperature,the emulsifier concentration,the initiator concentration and the monomer concentration on the apparent polymerization rates were investigated.The results showed that the monomer conversion and the grafting efficiency could reach 99.1%,54.9%,respectively,under the conditions where the reaction temperature was 50 ℃,the dosage of initiator tert-butyl hydroperoxide/tetraethylenepentamine（t-BHP/TEPA） was 0.5% （based on the mass of dry chlorene rubber latex（CRL））,mass ratio of monomer to polymer was 3：5,and the amount of emulsifier sodium dodecylbenzenesulfonate（DSB） was 1% （based on the mass of monomer）.The kinetics equation Rp=Kc（E） 0.15c（I） 0.30c（MMA） 1.41,where K is a constant,was obtained.The overall activation energy for the polymerization process was 60.2 kJ/mol within 40 ～ 55 ℃.The graftcopolymerization reaction follows the free radical mechanism generally.