The Study On Nucleating Agent For Crystallization Behavior And Crystallization Kinetics Of PBT

The poly (butylene terephthalate) (PBT) was used as the matrix resin, while mica and SiO2-coated mica, the Recycled Polytetrafluoroethylene, and NAV101 were used as nucleating agent to modify the nucleated crystallization of PBT by melt blending method in this article.Firstly, mica and SiO2-coated mica were used as inorganic nucleating agents, and PBT/mica and PBT/SiO2-coated mica composites were prepared by melt blending.The crystallization behavior was investigated by differential scanning calorimeter (DSC) and X-ray diffraction (WAXD). The DSC results showed that the addition of mica and SiO2-coated mica both increased the crystallization peak temperature of PBT. Compared to PBT, the crystallization peak temperatures of PBT/mica blend and PBT/SiO2-coated mica blend increased by 3.6℃ and 5.0℃, respectively.Furthemore.the modified Jeziorny equation, Ozawa equation and Liu-Mo equation were used to investigate the non-isothermal crystallization of PBT/mica and PBT/SiO2-coated composites. It was found that, the nucleation index of the PBT/mica blends was around 3.0. The composites showed three-dimensional nucleation growth pattern. Besides, from the WAXD results, we found that the addition of mica compound did not change the mechanism of nucleation and crystal growth mode of PBT. Kissinger model showed that the crystallization activation energy of the PBT/mica blends were lower than that of pure PBT. The mica compound accelerated the crystallization process of PBT.Secondly, The Recycled Polytetrafluoroethylene (before and after grinding) were used as nucleating agent to modify Poly(butylene terephthalate) (PBT). The phase morphology, rheological behavior of the PBT/r-PTFE blends were investigated by rotation rheological, DSC, POM and WAXD. The results showed that the addition of r-PTFE increased the values of processing torque. The crystallization peak temperatures of the PBT were increased by 4.84℃ and 6.36℃ after adding the r-PTFE before and after grinding. The results of rheological indicated that the PBT/r-PTFE blends displayed a "shear thinning" feature. Besides, the dispersion was more uniform in the matrix with the r-PTFE after griding.Finally, the nucleating agent NAV101 was used to prepare PBT/NAV101 blends.The results showed that the NAV101 could act as the heterogeneous nucleating agent to improve the crystaline properities of PBT resin. The crystallization peak temperature was 14.43℃ higher than the pure PBT blends, and the crystallization activation energy decreased about 65.9 kJ-mol-. Comparing the Jeziorny equation, Ozawa equation and Liu-Mo equation, it was found that the Liu-Mo equation can describe the non-isothermal crystallization process for PBT, but the Mo model provided a good fitting.