ACR-g-PVC复合粒子结构与对PVC的增韧效率

STRUCTURE OF ACR-g-PVC COMPOSITE PARTICLES AND THEIR EFFICIENCY IN PVC TOUGHENING

采用丙烯酸丁酯 (BA)和丙烯酸 2 乙基己酯 (EHA)交联共聚物为核 ,BA与EHA或甲基丙烯酸甲酯(MMA)与苯乙烯 (St)或MMA与丙烯酸乙酯 (EA)交联共聚物为壳 ,合成了 3种聚丙烯酸酯 (ACR) [P(BA EHA)、ACRⅠ、ACRⅡ ]胶乳 .以 3种ACR胶乳为种子 ,分别与氯乙烯 (VC)进行乳液接枝共聚 ,制备了相应 3种复合粒子 (ACR g PVC) .借助动态光散射法和透射电镜考察了ACR与复合乳胶粒的粒径与结构 ,表征了所研制材料的形态和冲击韧性 .研究结果表明 ,3种ACR g PVC材料的常温缺口冲击强度随ACR含量增加而显著提高 ,其突跃点的发生具有等橡胶量效应 ,其临界橡胶含量约为 4 % ,并采用脆 韧转变的临界粒子间距模型对其进行了解释 ;P(BA EHA)比核 壳ACRⅠ或ACRⅡ具有更高的增韧效率 ,依据复合粒子的两种理想结构模型对其增韧效率进行了分析 .

Three kinds of core-shell polyacrylate latices (abbreviated to P(BA-EHA), ACR I and ACR R) were synthesized by multi-stage emulsion polymerization. Butyl aerylate, 2-ethylhexylacrylate and 1,4-butanediol diacrylate were used as components of the ACR core,while butyl acrylate/2-ethylhexylacrylate or methyl methacrylate/ styrene or methyl methacrylate/ ethyl acrylate were employed as components of the ACR shell, respectively. Using ACR latices as seeds, three kinds of ACR-g-PVC resin were prepared by seeded emulsion co- polymerization with vinyl chloride. The structure and sizes of ACR and composite latex particles were investigated through transmission electron microscopy and dynamic laser scattering method. The morphology and impact toughness of the obtained materials were charaeterized. It was found that the notched impact strength of the three kinds of ACR-g-PVC materials at room temperature was enhanced with an increasing ACR content. The abrupt increment of the notched impact strength for the ACR-g-PVC materials happened at the same rubbery content of about 4 % This was explained by the change of interparticle distance. The toughening efficiency of P ( BA-EHA) was higher than that of ACR I or ACR U The toughening efficiency of ACR in the materials was discussed according to two ideal-structure models of the ACR-g-PVC composite particles.