St/MMA共聚物的热性能

THERMAL BEHAVIORS OF St/MMA COPOLYMER

通过乳液聚合法合成了苯乙烯 (St)、甲基丙烯酸甲酯 (MMA)二元共聚物 (PMS) ,并分别利用 α-甲基苯乙烯 (α- MSt)、丙烯酸乙酯 (EA)作为改性单体代替部分苯乙烯 (或 MMA)合成了三元共聚物。用凝胶渗透色谱 (GPC)测定了聚合物的分子量及其分布 ,利用热分析仪测定了聚合物的玻璃化温度及分解温度。结果表明 ,二元共聚物的玻璃化温度随 St质量分数的增加成曲线变化 ,在 St占 5 0 %时玻璃化温度达到最高值。α- MSt的加入 ,使玻璃化温度升高 ,EA的加入使玻璃化温度降低。二元共聚物的热分解起始温度和半衰期温度随 St质量分数的增加先增加后降低 ,在 St占 5 0 %时二者均达到最高值 ;三元共聚物中 ,加入 α- MSt后 ,热分解起始温度升高 ,半衰期温度降低 ,EA的加入降低了起始分解温度和分解半衰期温度。

The bipolymer(PSM) and terpolymer(PSMEA,PSMMS) was synthesized by emulsion polymerization. The glass transition temperature (T g ) of copolymers and relationship between T g with components were studied by DSC. The results show that T g of bipolymer have a peak value at about the content of 50% MMA (in mass). When the α-MSt was added. T g of terpolymer raised with the increasing content of α-MSt, while T g of tercopolymer decreased with the increasing content of EA. The thermostability was determined by TGA. The thermal decomposition temperature of bipolymer have a peak value at about the content of 50% MMA (in mass). When the α-MSt was added, the thermal decomposition temperature increased, but the temperature of mass loss in 50%(T d50 ) decreased. EA made the thermal decomposition temperature and temperature of mass loss in 50%(T d50 ) decrease. This shows that EA can decrease the temperature of mechanical for MCS resin.