| The different proportion of PET/PBT blends were prepared with solution blending, hot-pressing blending, single and twin-screw extruder, and the reactive extruder melt extrusion blending. Intrinsic viscosity, crystallization behavior, transesterification, mechanical properties and PMDA chain extender of the blends were characterized with Ubbelohde viscosity meter, NMR, DSC etc. Besides, the appropriate processing temperatures, screw speed, water content were also studied.The results show that the intrinsic viscosity of blends extruded with reactive extruder increases approximately10%when the content of PBT increases10%. The vacuum system of reactive extruder could exclude water effectively and timely, significantly reducing material degradation. The intrinsic viscosity of blends was reduced by more than20%when using the low viscosity of PET compared to the high. The intrinsic of blends produced with twin-extruder is the lowest in all, on the contrary, with reactive extruder is the highest in all.The DSC spectra showed that of preparation products with solution blending and with single-extruder are the same. Peak temperature of melting tiny improved with increasing of PBT. The peak temperature of PET basically unchanged which were produced with twin-extruder.The PET/PBT blends extruded by different type extruders haven’t occur ester exchange reactions characterized by13C-NMR. or maybe the generated amount of the copolymer is too small, so that the13C-NMR can’t detect. There isn’t ester exchange reaction occur apparently after heating at260℃within30minutes.The impact properties of blends increased with increasing of PBT. But the Phase separation of the blends may be serious when the PBT content at high point, reducing the impact performance. The toughness of the blends will be improved by the PBT and have the maximum value at the proportion of50:50.The intrinsic viscosity of PET/PBT blends extruder by reactive extruder have significant effect when add PMDA. The temperature of polycondensation segment at260℃and the value of vacuum degree at0.1MPa are the suitable reactive process conditions. The blends doesn’t have new group generated after chain extender by PMDA.Extruder type and processing conditions on the intrinsic viscosity with high viscosity PET were studied, the results show that the intrinsic viscosity of the product extruded by single-extruder was reduced the lowest in all. The intrinsic viscosity of PET reduces by an average of23.5%at different screw speed with twin-extruder. Single-screw extruder is most appropriate for drying PET processing with the conditions of low temperature, high screw speed. |
