Pp / Inorganic Nano-particle / Tata / Poe Composites Of The Preparation, Structure And Performance

The effects of nano-CaCO₃ (or nano-SiO2), (3-nucleating agents (N,N,N',N'-tetraalkyl terephthalamide, TATA), and elastomer (POE) on the structure and mechanical properties of PP were studied in this thesis. A PP composite with high strength and toughness was obtained.Oleic acid (OA) modified SiO₂ or CaCO₃ nanoparticles was prepared using surface modification method. IR results showed that oleic acid has attached to nano-CaCO₃ surface by ionic bond and the optimum content of OA was 7.5%. OA modified SiO₂ or CaCO₃ nanoparticles dispersed in heptane more stably than unmodified ones, and nanoparticles modified by OA also dispersed well in PP. The crystallization behavior of PP was studied by means of DSC. It was found that nano-CaCO₃ or nano-SiO₂ significantly increased the crystallization temperature, crystallization degree and crystallization rate of PP, and the addition of modified SiO₂ or CaCO₃ nanoparticles could effectively lead to the formation of β-crystal PP due to the heterogeneous nucleation. Effect of the OA modified SiO₂ or CaCO₃ content on mechanical properties of PP nanocomposites was also studied. The results showed that the modified SiO₂ or CaCO₃ could effectively improve the mechanical properties of PP.The effect of N,N,N',N'-tetraalkyl terephthalamide (TATA) on the melting behavior of PP was studied by means of DSC. With the increase of TATA content the degree of crystallinity for β-crystal PP increased, and that for a-crystal PP decreased abruptly, which showed that TATA effectively induced the formation of the β crystal PP. When the content of TATA was 0.3% the content of β-PP was up to 96.1%. WXRD also revealed the formation of the p crystal PP after the introduction of TATA into PP and with the increase of TATA content the intensity of the diffraction peak for β-crystal PP increased, indicating that TATA effectively induced the formation of the p crystal PP.The effect of TATA on nonisothermal crystallization kinetics of PP was studied by DSC. It was found that TATA remarkablely increased the crystallization temperature and decreased the half-crystallization time (t/_1/2) and Avrami exponent (n) of PP at the same cooling rate, indicating that TATA influenced the crystallization rate and crystallization growth mode of PP. TATA increased the crystallization rateconstant of PP (Zc), which further indicated that the crystallization growth rate of PP was accelerated by the addition of TATA. The activation energies of PP have been evaluated by Kissinger method. The unit cell constant of PP was studied by WXRD and the results were a=b=19.08A and c=6.49A, indicating the existence of hexagonal crystal after the introduction of TATA into PP.The crystalline morphology of PP was studied by polarized optical micrographs (POM). It was found that the addition of TATA led to a substantial decrease in the size of spherulites of PP and the boundaries of spherulites were hardly distinguished. TATA could significantly improve the impact strength, flexural strength and modulus of PP, while the tensile strength of PP did not change greatly with TATA content.Nano-CaCO3 (or nano-SiO2), N.N.N'.N'-tetraa&kyl terephthalamide (TATA), and POE elastomer were used to modify the mechanical properties of PP, and a PP composite with high strength and toughness was obtained. The results showed that Nano-CaCC>3 (or nano-SiO2), TATA, and POE elastomer could significantly improve the toughness of PP. When the POE content was 3%, Nano-CaCO3 (or nano-SiO2) and POE had the synergetic effect in strengthening and toughening PP.