微悬浮法CaCO_3表面接枝PMMA及其在PVC中的应用

Surface Modification of CaCO_3 by Grafting PMMA and the Application in PVC

在水介质中,超声作用下用油酸对纳米碳酸钙进行表面修饰,再以微悬浮原位聚合法用PMM A进行接枝包覆,成功制备了PMM A/C aCO3复合粒子。借助透射电镜(TEM)、红外光谱(FT-IR)、热失重(TG)等分析手段对复合粒子的形态结构进行了表征。实验结果表明,油酸可通过羧酸盐的形式吸附于碳酸钙粒子表面,一定量PMM A通过油酸分子的不饱和双键接枝于碳酸钙粒子表面。将所得PMM A/C aCO3复合粒子与PVC共混制得PVC/PMM A/C aCO3复合材料。复合材料的TEM照片表明,C aCO3粒子非常均匀地分散在PVC基体中,两相界面模糊。随着PMM A/C aCO3纳米复合粒子用量的增加,复合材料的强度和韧性同时提高。当复合粒子用量高于12%时,复合材料的冲击强度可提高3倍,而拉伸强度下降很少。

PMMA/CaCO3 composite particles were synthesized by micro-suspension polymerization. The CaCO3 was firstly treated with oleic acid （OA） which has unsaturated bond, followed by MMA radical grafting through micro suspension polymerization. The morphology of the composite particles were characterized by means of TEM, FT-IR and TG. The experimental results show that the OA molecules bond to and align on the particle surface, which led to the formation of carboxylate salts. Some PMMA chains were grafted onto the surface of CaCO3 particles through the unsaturated bond of OA molecules. PVC/PMMA/CaCO3 composite material was prepared by blended PMMA/CaCO3 composite particles with PVC matrix. TEM shows that the CaCO3 particles are uniformly dispersed in PVC matrix, the interface between the two phases is indistinct. With increasing content of the fillers, the notched impact strength and the tensile strength of PVC/PMMA/CaCO3 composite material improve simultaneously. When the filler loads are higher than 12% （wt）, the impact strength of composites increases above 3 times that of PVC, while its tensile strength becomes little lower.