聚α-甲基苯乙烯空心微球的开裂机理

Formation Mechanisms of Crack on Surface of Poly-Alpha-Methylstyrene Shells

干燥过程是制备高表面质量聚α-甲基苯乙烯(PAMS)空心微球的关键过程之一。文中通过实验研究了不同热处理温度(55℃、75℃、95℃)和不同干燥温度(室温、45℃、65℃、85℃、100℃)对PAMS空心微球干燥过程的影响。实验结果表明,采用不同温度对PAMS空心微球进行热处理后,具有严重初始微缺陷的空心微球所占百分比没有显著差异。因为最高热处理温度(95℃)远远低于PAMS的玻璃化转变温度(≈180℃)而不能使PAMS分子链段运动以消除残余内应力。随着干燥温度的升高,干燥后的空心微球表面出现裂纹的比例相应增加。干燥温度的升高将会导致空心微球球壳所受应力不断增大。而球壳所受应力是其产生裂纹的主要原因之一。

Drying is one of the most important processes to prepare hollow poly-alpha-methylstyrene (PAMS) shells. Effects of the heating treatment temperature and the drying temperature on the PAMS drying process were investigated. Effect of the heating treatment temperature on the percentage of PAMS shells with initial defects can be neglected, because the highest heating treatment temperature (95 ℃) is far below the glass transition temperature of PAMS (180 ℃) so that the polymer chains cannot move for rearrangement to release a great deal of residual stress. With the increase of drying temperature, the percentage of PAMS shells with cracks onto the surface increases, because the stress inside PAMS shells increases correspondingly.