苯乙烯本体聚合动力学研究

在苯乙烯单体聚合转化率不超过50%情况下,得到本体热聚合引发反应速度与单体浓度三次方呈线性关系,如果添加引发剂偶氮二异丁腈则其聚合速度与引发剂的0.5次方呈正比。根据Arrhenius 方程式求得的苯乙烯热聚合活化能 E_α=110.5kJ/mol,在引发剂 AIBN 存在下的活化能 E_α′=65.3kJ/mol。引发剂的存在促进游离基生成,加快聚合反应进程,使聚合物分子量分布较宽。添加十二碳烷硫醇作链转移剂,也有使聚合物分子量分布变宽和降低分子量的趋势,添加量超过0.2%则使聚合速度降低。另外,低温聚合的聚合物分子量大,分子量分布均匀。

A Study on Kinetics of Bulk Polymerization of Styrene

A study on kinetics of bulk polymerization of styrene for preparing plasticoptical fibers was performed.The rates and molecular weights of polymer havebeen measured in presence of initiator AIBN and chain transfer agent dodecylmercaptan over a wide range of temperature.The initial polymerization rate islinearly related to the concentration of styrene monomer raised to the third power,and to the square root of the initiator concentration under conversions of below50%.According to Arrhenius equation,the activation energy of bulk thermalpolymerization of styrene is E_α=110.5kJ/mol and,in the case of presence of initi-ator,E_α~′=65.3kJ/mol.The initiator in the system tends to promote free radicalformation,increase polymerization rate and broaden polymer molecular weightdistribution.Other factors including temperature,chain transfer agent etc.affe-cting molecular weight and its distribution are also discussed. These results areuseful for investigating transparency of plastic optical fibers and filament draw-ing as well as controlling molecular weight of polymer in polystyrene productionprocess.