纳米二氧化硅对卡波姆凝胶流变行为的影响

Effect of Nanosilicas on the Rheological Behaviors of Carbopol Gel

摘要:

采用红外光谱（FT-IR）和扫描电子显微镜（SEM）分析了气相法二氧化硅（FS）和沉淀法二氧化硅（PS）的表面性质，结果表明FS表面比PS含有更多的羟基，在水中分散性更好。利用流变仪对比研究了FS和PS对卡波姆956凝胶流变行为的影响规律，结果表明，FS和PS的加入均能明显提高卡波姆凝胶的弹性模量、屈服应力、触变性等流变学性质；在纳米二氧化硅浓度小于等于4%时，FS在卡波姆凝胶中分散粒径较小且更均匀，其对上述流变学性质的增强作用大于PS; 纳米二氧化硅浓度从4%增大到8%时，PS形成大团聚体，能更好地提高上述流变学性质。结合SEM的测试结果阐明了FS与PS同卡波姆之间不同的相互作用方式。

Abstract:

This paper investigates the effects of fumed silica (FS) and precipitated silica (PS) on rheological behaviors of Carbopol gel. The elasticity modulus, yield stress, and thixotropy of Carbopol gel can be improved efficiently with the addition of either FS or PS. When the nanosilica concentration was less than 4%, the particle size is smaller and more uniform for FS-modified gel than PS-modified gel, leading to a more dramatically enforced rheological properties for the former; when the nanosilica concentration was increased from 4% to 8%, PS forms large agglomerates and therefore improves rheological properties. Results of fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) show that FS has more hydroxyls on its surface than PS as well as better dispersion in water. Different interaction ways of FS and PS with Carbopol were related to various surface properties.