Non-isothermal crystallization kinetics and mechanical properties of polybutylene terephthalate/polycarbonate blends modified by toughening agent

The polybutylene terephthalate(PBT)/ polycarbonate(PC)blends modified by toughening agent(S-2001)consisting of methyl methacrylate,styrene and silicone were prepared via melt blending.The non-isothermal crystallization kinetics of the blends were investigated by scanning calorimetry(DSC)at different cooling rate of 5℃·min-1,10℃·min-1,15℃·min-1,and the data were analyzed by using modified Avrami theories of the Jeziorny method.The influence of toughening agent(S-2001)on crystallization and mechanical properties of PBT/PC blends was discussed.The microstructure of toughened PBT/PC blend was observed by scanning electron microscopy(SEM).The results showed that the crystallization rates of the toughened PBT/PC blends increased as the cooling rate increased;the non-isothermal crystallization rate constant Zc decreased,the crystallization half time t1/2 increased,crystallinity of PBT decreased with increasing amount of toughening agent(S-2001)at the same cooling rate,which indicated that the addition of toughening agent(S-2001)had a negative effect on the crystallization of PBT.Toughening agent(S-2001)provided good compatibility with PBT and PC.As the amount of toughening agent(S-2001)increased,the toughness and elongation at break of PBT/PC blends significantly increased,the SEM of Izod impact section for toughened PBT/PC blend indicated the change of its Izod impact section from fragility break into toughness break.When the content of toughening agent(S-2001)was 15 parts per hundreds of PBT/PC,the Izod impact strength of PBT/PC blends reached 67 kJ·m-2.But the rigidity of PBT/PC blends decreased a little.