核壳比对聚丙烯酸酯塑溶胶流变-凝胶行为的影响

The effects of core/shell ratio on rheological properties and gelation of polyacrylate plastisol

采用半连续种子乳液聚合法制备了5种不同核壳比(核层和壳层的质量比分别为10/0、8/2、7/3、6/4、5/5)的聚丙烯酸酯乳液。用旋转流变仪研究了核壳比对聚丙烯酸酯塑溶胶流变-凝胶化转变行为的影响,并用动态光散射(DLS)和扫描电镜(SEM)对乳胶粒子的大小、形貌和塑溶胶胶膜表面进行表征。流变测试结果表明增塑后体系粘度随着剪切速率的增大而减小,呈非牛顿流体行为;乳胶粒子核壳比越大,增塑后体系的粘度越大,凝胶点温度越低,塑溶胶的储存期越短;频率扫描显示随着扫描频率的增加凝胶体系的粘弹性模量近似线性缓慢增加,说明此凝胶体系的稳定性较好。

Different polyacrylate latexes with core-shell structure were prepared by semi-continuous seed emul- sion copolymerization using various core/shell ratios （the ratio to monomer is 10/0, 8/2, 7/3, 6/4, 5/5 respec- tively）. The effects of core/shell ratio on the rheological behavior and gelationconversion of polyacrylate plasti- sol were investigated by rotary rheometer. The size and morphology of latex particle and plastisol surface mem- brane were characterized by dynamic light scattering （DLS） and scanning electron microscopy （SEM）. The re- sults of the rheological test demonstrated that plasticized system presented a bigger viscosity and lower gel tem- peratureas well as shorter storage period with the core/shell ratio increasing; plasticized system viscosity de- creased with shear rate increased, which shows the non Newton fluid behavior~ frequency scan result displayed the gel system for viscoelastic modulus linearly increased slowly as the scanning frequency increased, suggesting that the present system has a better stability.