Effect Of Reactive Compatibilizers On The Structure And Properties Of PBT/ABS、PBT/PP Blends

Although poly(butylene terephthalate)(PBT) developed at the lasted among the top5engineering thermoplastics, as a a semicrystalline thermoplastic, it grows in the fastest. Now PBT has been widely used in auto, electronics and electrical industries due to its excellent tensile properties, high abrasion and chemical resistance. However, low notched impact strength and poor dimensional stability of a pure PBT limits its extansive application. Modification of PBT by blending is found to be an effective way to obtain a high performance material. Unfortranutly, most of stydies focused on improving compatibility, optimizing processing and upgrading equipment, but the blending systems compatiblized with compatiblizer all are obtained by controlling the morphology of dispersed phase, moreover, the aggregation structure of the blends is strongly dependent on its rheology behavior. So it is necessary to investigate the relationship of the rheological behavior and morphology of polymer blend.In this study, the morphology and rheological behavior of PBT/ABS blending system were studied, the influence of compatiblizer on the morphology of the dispersed phase and the rheological behavior of PBT/ABS and PBT/PP blending systems were investigated.On a RM-200B torque rheometer, the amorphous tri-block copolymer ABS and semicrystalline PBT were employed to prepare PBT/ABS blending system via melt banburying process. The morphology and rheological properties of the blend were investigated using SEM and rotation rheological analyzer respectively. The morphology of the blending systems changes from "sea-island" into co-continuous with increasing ABS mass. The phase inversion occurs at ABS content of40-60wt%. The result is in agreement with those predicted by the viscous model. The melt complex viscosity values of the systems were also evaluated by various theoretical models. The experimental values show a negative deviation from the additivity rule. Cole-Cole and Han plots illuminate that PBT/ABS blends are partially miscible. The storage and loss modulus of ABS-enriched blends show a better correspondence with the Palierne model than PBT-enriched blends.In order to increase the miscibility of PBT/ABS blend, grafted polymer ABS-g-(GMA-co-St) was prepared by melt-grafting method using glycidyl methacrylate(GMA) as grafting monomer and styrene(St) as comonomer, The grafted polymer is characterized by infra-red spectroscopy and the percent grafting is obtained by chemical titration. The prepared ABS-g-(GMA-co-St) was used as compatibilizer to obtain PBT/ABS/ABS-g-(GMA-co-St) by melt compounding of PBT and ABS. The results show that the grafting degree(GD) reachs a maximum value of4.06%at0.5%DCP,8%GMA and8%St. The size of ABS droplets is in minimum value in the PBT/ABS(70/30) blend with3wt%ABS-g-(GMA-co-St) compatibilizer. The interfacial tension of the PBT/ABS(70/30) blend was calculated to be of28.08and1196mN/m respectively using the Palierne emulsion and Choi-Schowalter models. And the corresponding mechanical properties and tensile strength of the blend were improved with73%and8%, respectively.PP-g-MAH, POE-g-MAH and POE-g-GMA compatibilized PBT/PP blends were prepared by melt blending respectively. The effect of various compatibilizers on the dispersion morphology and rheology behavior of PBT/PP blends with different PP concentrations was also investigated. The results illuminate that all compatibilizers used can improve miscibility between PBT and PP, and POE-g-GMA shows a better effect. It is also clear that the presence of compatibilizer can decrease the size of the dispersed particles. However, for a PBT-enriched component, the influence is not so obvious. The storage modulus is found to increase with raising compatiblizer dosage, suggesting decrease in interfacial tension and prolonging relaxation time of the reactive blend.