分散介质对纳米二氧化硅分散体系流变性能的影响研究

Research on effect of dispersion medium on rheological properties of nanometer SiO2’s dispersion system

测定了不同分散介质以及同一分散介质不同相对分子质量、不同温度下的纳米二氧化硅分散体系的流变性能并进行了比较,得出以下结论:随着分散介质相对分子质量的增加,分散体系的粘度增加,固液间氢键作用力减弱,分散体系所需临界剪切应力减小;当分散介质的相对分子质量提高到一定程度后,固液间氢键作用力更弱,加上分子链增长造成空间位阻效应,纳米二氧化硅难于以三维网状立体结构存在于分散介质中,不会出现先剪切变稀后剪切增稠的流变曲线。分散体系所处的温度越高,体系的粘度越低,剪切增稠所需临界剪切应力越大,剪切增稠效果越差,甚至不出现先剪切变稀再剪切增稠的流变曲线。因此选择合适的分散介质及分散温度对改善纳米二氧化硅分散体系的流变性能有积极作用。

The rheological properties of nanometer SiO2’s dispersion system under the conditions of different dispersion mediums,as well as the different relative molecular mass and temperature of one single dispersion medium were determined and compared.The results showed that with the increasing of the relative molecular mass,the dispersion system′s viscosity increased,the hydrogen bonding between solid and liquid weakened and the critical shear stress needed by dispersion system decreased.When the relative molecular mass of dispersion medium increased to some extent,the hydrogen bonding between solid and liquid was weaker and space steric effect was caused by the growth of molecular chain.Then the nanometer SiO2 was not existent with three-dimensional netted structure in dispersion medium,the rheological properties curves didn′t have shear thinning first and then shear thickening.With the increasing of the dispersion medium′s temperature,the dispersion system′s viscosity decreased,the critical shear stress for shear thickening increased,the effect of the shear thickening became worse,and even the rheological properties curves didn′t have shear thinning first and then shear thickening.So selecting suitable dispersion medium and dispersion medium′s temperature can improve the rheological properties of nanometer SiO2’s dispersion system.