纳米CaCO3/PVC增塑糊体系触变性能研究

研究了纳米CaCO3/PVC增塑糊体系的触变性能,并在分析纳米CaCO3/PVC增塑糊体系中作用力、增塑糊中物CaCO3粒子分布状态的基础上建立了纳米CaCO3/PVC增塑糊体系的微观结构模型,依据该模型提出了纳米物CaCO3/PVC增塑糊体系的触变性行为机理。结果表明,从触变性能出发,纳米CaCO3的填充量存在一个最佳范围;随着剪切力的增大,CaCO3粒子间拟网络结构的平衡状态逐渐被破坏,体系的微观结构形态发生变化,粒子间的距离被拉开,颗粒间的作用力由排斥转变为吸引。在外部剪切力消除后,布朗运动和团聚体颗粒间的吸引力使得体系又恢复到静止状态的拟网络结构,但恢复过程需要一定时间,从而使体系体现出触变性行为。

Study on Mechanism of Thixotropy of Polyvinyl Chloride Paste Resin Filled with Nano-sized Calcium Carbonate

The thixotropy of nano-CaCO3/PVC plastisol system was studied and a microstructure model of nano-CaCO3/PVC plastisol system was established on the base of analyzing the interactions in nano- CaCO3/PVC plastisol system and the distribution of CaCO3 particles in plastisol. Thixotropic mechanism of nano-CaCO3/PVC plastisol system was put forward in terms of the model. The results indicated that there is an optimum range for filling amounts of nano-CaCO3 considering thixotropic property. With the increase of shear strength, the equilibrium of quasi-net structure amoung CaCO3 particles is destroyed gradually, microstructure of the system is changed, and space among CaCO3 particles becomes larger and interaction between particles changes from repellence to attraction. After external shear force was removed, the system restores the quasi-net structure in a still state due to Brown movement and attraction in aggregated particles. The system thus exhibited thixotropic property since this restoring process needs a certain time.