Properties Study Of PTFE/nano-CaCO₃ Composite

Studies of common polymer materials with high performance and multiple functions have been the focus of much recent research. Compared with traditional modification methods, the incorporation of nano-particles into polymers provides a novel way for the modification of the polymer due to the particular properties of nano-particles. The surface modification method, surface nature and the content of nano-particles govern the structure and performance of the resulting polymer composites. Therefore, it's very important to systematically study the surface modification methods of nano-particles and the relationship between the properties and structure of the composites.In this paper, the dispersion-stabilization mechanism of the novel surface treatment of nano-CaCO₃ with both titanate coupling agent and dispersant were also studied. The results showed that the surface modified particles superficial coat had been blanketed with organic film and well dispersed in the bulk material. Nanophase materials modified PTFE (polytetrafluoroethylene) was made by process of mixing round, pressing and free-sintering. And the influence of CaCO₃ content and interfacial structure on the static mechanical properties of PTFE/nano-CaCO₃ was studied. The results showed that the elastic modulus of the composites increased with increasing nano-CaCO₃content. The impact strength and breaking elongation reached a maximum value at a content of 3 phr CaCO₃ which was unmodified. But the tensile almost remained decrease at lower CaCO₃ content not sharply.The isothermal crystallization of PTFE/nano-CaCO₃ and its kinetics were investigated by DSC. The results showed that the lower CaCO₃ content had no obvious influence on the crystallization temperature of the composites, indicating that the nucleating effect of CaCO₃ was not significant. The interfacial structure of the composites had an influence on the crystallization behavior of the composite melts, which was indicative of a nucleating effect of nano-CaCO₃. A study of the isothermal crystallization kinetics using the Avrami method showed that the half crystallization time t_1/2 of the composites changed little. The Avrami index n of the composites filled with compatibilizer and high content of CaCO₃ decreased which was anindication of the nucleating effect of the filler.In this paper, pore model was upbuilt and the mechanics of nucleation, growth, solution were also discussed.