淀粉接枝聚丙烯酰胺凝胶的流变性能

为了克服以聚丙烯酰胺作为主剂制备凝胶类调剖堵水剂时溶液黏度大不易泵入、易被剪切等缺陷，采用羟丙基淀粉(HPS)接枝的方法改善了聚丙烯酰胺强凝胶的性能，利用HAAKE流变仪及ESEM研究了凝胶的流变性能与微观结构，考察了主剂(丙烯酰胺(AM)+HPS)含量、AM/HPS质量比、交联剂浓度和纳米级SiO2浓度对凝胶流变性的影响。结果表明：随主剂含量与AM/HPS质量比增大，凝胶体系弹性模量和黏性模量增大，屈服应力也增大，柔量减小，形变幅度减小，回复率增大；随着交联剂浓度增大，凝胶强度先增强后减弱，屈服应力渐增；加入纳米级SiO2有利于增强凝胶的强度、弹性及屈服应力；ESEM测试结果表明，加入羟丙基淀粉与纳米级SiO2后的凝胶可观测到致密的三维网络结构，可能是凝胶强度增强的原因。

Rheological Properties of Starch Graft Polyacrylamide Gel

High solution viscosity of gel plugging agent prepared by polyacrylamide as the main agent usually results in problems such as difficulty in pumping and proneness of being sheared. To overcome these defects, this study improved the properties of acrylamide （AM） gel by hydroxypropyl starch （HPS） graft. Rheological properties and microstructure of the gels were studied by HAAKE rheometer and ESEM. The effects of the main agent mass fractions and AM/HPS mass ratio, crosslinking agent concentration and nanoscale SiO2 concentration on rheological properties of the gels were investigated. The results showed that, as both of the concentration and mass ratio of AM and HPS increase, the viscoelastic moduli and yield stress of the gel increase, whereas the compliance and deformable amplitude decrease, and the corresponding recovery rate rises instead.Moreover, with the increase of crosslinking agent concentration, the strength of the gel system first increases and then decreases, and the yield stress increases. The addition of nanoscale SiO2 enhances the strength, elasticity and yield stress of the gel. Test results from ESEM show that there is a denser three-dimensional network structure observed in the gel with hydroxypropyl starch and nanoscale SiO2, which could be the cause of increased strength of the gel.