改性纳米CaCO3水相分散体系流变行为及其流变参数拟合(Ⅰ)--铝锆偶联剂用量对分散体系流变行为的影响

Rheological Experiment and Parameter Fitting of Modified Nanosized CaCO_3 Dispersion in Water——Effect of Zircoaluminate Coupling Agent Amount on Dynamic Rheological Properties for the Dispertion

采用铝锆偶联剂对纳米CaCO3进行表面改性,对改性纳米CaCO3水相分散体系的流变数据进行测定,并借助非牛顿流体模型实现流变参数的拟合。结果表明,在低剪切速率下,改性纳米CaCO3水相分散体系的表观黏度随着剪切速率的增大而下降,即剪切变稀,呈现假塑性流体特性;在高剪切速率下,随着剪切速率的增大,分散体系的表观黏度变化很小,呈现近牛顿型流体特性。采用铝锆偶联剂对纳米CaCO3进行表面改性,可明显改善纳米CaCO3在水相体系中的流动性,使屈服应力、零剪切黏度及极限黏度都明显减小。根据Herschel-Bu lk ley模型拟合结果,未经表面改性的纳米CaCO3水相分散体系的流动特性指数和屈服应力分别为1.489和2.767 Pa,呈现剪切变稠流动趋势,表明分散体系的不稳定性,部分粒子发生团聚;而经2.0%铝锆偶联剂改性的纳米CaCO3水相分散体系的流动特性指数和屈服应力分别为0.880和1.250 Pa,呈现明显的假塑性流体特性,分散体系流动性较好。

Rheological experiment of aqueous dispersion of nanonized CaCO3 modified with zircoaluminate coupling agent was carried out,and the rheological parameters of the dispersion samples were also studied.The results showed that,at low shear rate,the dispersion containing modified nanosized CaCO3 exhibited the behavior of pseudoplastic fluid,characterized as obvious shear thinning.At high shear rate,the rheological behavior of the dispersion was similar to Newtonian liquid.It was inferred that surface modification process had profound effect on the flow behavior of nanosized CaCO3 in water.According to Herschel-Bulkley model fitting result,it was found that the flow behavior index and yield stress of modified nanosized CaCO3 dispersion was 0.880 and 1.250 Pa,showing the flow behavior of shear thinning,which was attributed to the good dispersion stability.However,in the fixed detection range,the flow behavior index and yield stress of unmodified nanosized CaCO3 dispersion was 1.489,2.767 Pa respectively,exhibiting the rheological behavior of shear thickening,which was ascribed to the intense dispersion agglomeration.