Study On PC/PET Alloy

Polycarbonate(PC) and polyethylene terephthalate(PET) is very widely used two kinds of engineering plastics. PC/PET alloy can improve the PC processing illiquid, poor stress cracking resistance and poor solvent resistance, to improve PET impact strength and aging resistance, decrease the cost of the PC at the same time, mainly used in auto parts. Although PC and PET has a certain compatibility, the toughness of PET is too poor to influence the alloy the impact property. Therefore, selecting the best ratio of substrate, add the appropriate compatibilizer, flexibilizer, to improve the performance of PC/PET alloy become a problem to be solved.This paper studied the different ratio of substrate, compatibilizers and flexibilizers on the properties of PC/PET alloy respectively. The mechanical properties, thermal properties, rheological properties, crystallization properties, thermal stability and others was discussed and studied by electronic universal testing machine, differential scanning calorimetry (DSC), scanning electron microscope(SEM), melt flow rate instrument, capillary rheometer, microcomputer control thermal deformation vicat softening machine, plastic indentation hardness tester, polarizing microscope(POM), Fourier transform infrared spectrometer. The concrete research content is as follows:(1) The different ratio of substrate on the properties of PC/PET alloy materials was compared.Studies show that there was no ester exchange reaction between PC and PET in the manufacturing process in a short time, the reaction alloy is mechanical mixture; the crystallization of PET was damaged by the addition of PC,so the crystallization temperature of PET is reduced, the crystallization speed is slow down,and the spherulite particles become smaller; PC/PET alloy is a partial compatible system,and when the ratio of PC/PET is 60/40, the Tgs of the two components are most closed, so this two components alloy system has the best compatibility, at the same time, at this ratio of the alloy not only has a good processing liquidity, but also can maintaining high rigidity and toughness,and the heat distortion temperature, hardness and other comprehensive performances are better.(2) The compatibilizing effects of three kinds of compatibilizers--the styrene-maleic anhydride random copolymer(SMA), polystyrene-ethylene/butadiene-polystyrene grafted maleic anhydride copolymer (SEBS-g-MAH) and polyethylene grafted maleic anhydride (PE-g-MAH) were compared to the PC/PET(60/40) alloy system. The results show that the alloy system has excellent comprehensive echanical properties, processing fluidity,good hardness and high thermal deformation temperature when adding five portions of PE-g-MAH compatibilizer; The dispersion phase of this system is small and uniformly distributed, the two phases bond tightly and the phases interface is fuzzy under the scanning electron microscope.So we can say that the compatibilizers—PE-g-MAH has played a good compatibilizers to the PC/PET(60/40) alloy system.(3) The toughening effects of two kinds of organic rigid particles--PS and AS were compared to the PC/PET(60/40) alloy system. Studies show that the alloy system not only has a high notched impact strength but also has a good rigidity when PS as the flexibilizer, and the melt fluidity,thermal deformation temperature and the hardness of PS toughening system is better than AS toughening system.(4) The effects of PS organic rigid particles toughening PC/PET(60/40) allay compatibilized by PE-g-MAH befor and after were compared. The results show that the toughening PC/PET alloy which was compatibilized by PE-g-MAH has better comprehensive performances and higher impact toughness than the PS directly toughening system, so it is appropriate to increase the compatibility of PC/PET(60/40) alloy befoer toughening by rigid particlesr.