Research On Physical Modification And Extruding Process Of PC/ABS Alloy

PC/ABS alloy is a kind of high performance engineering plastics. Because of its good processability, excellent resistance to impact, high distortion temperature and low cost, it has been widely used in industrial production and daily life. With the diversity of application needs and the specialization of application fields, the higher demand for the performance of PC/ABS alloy has been put forward, so high performance and functionalization of PC/ABS alloy become the focus of research. It’s necessary to study material preparing and performance improvement methods of PC/ABS composites. The study offers the theory basis to the application in the engineering and modifying methods for PC/ABS.The effect of composition in the mixture, compatilizers, short glass fiber, tougheners, flame retardants and processing parameters on mechanical property, flowing property, thermal properties and morphology of PC/ABS was analyzed. And valuable theoretical achievements, which applied to development and preparation of new PC/ABS composites, were acquired. Based on modification mechanism and technology, halogen-free flame retardant short glass fibers reinforced PC/ABS was developed, which was used for the front shell of large screen color TV.With the method of blending modification, PC/ABS alloy was analyzed from composition and compatibility. Through the adjustment of PC/ABS ratios, the effect of ABS content on mechanical property, flowing property, thermal property and morphology of PC/ABS blends was studied, and the best comprehensive performance was obtained at the ratio of80:20; The basis and the principle of the design and selection of compatilizers for PC/ABS blends was obtained by studying the compatibilizing effect and mechanism of MBS, MAH-ABS and SMA. The analysis on monorphology and performance of the three compatible system showed that the compatibility between PC and ABS could be greatly improved using a small amount of proper compatilizer, and the impact toughness of PC/ABS alloy also significantly improved.With features of high strength, large stiffness and lower shrinkage, short glass fiber reinforced PC/ABS can reduce the thickness of workpiece and achieve an ultrathin effect for outer casing of electrical appliance. Besides, the forming process is simple and with less wear to equipment. Research on short glass fiber reinforced PC/ABS mixture was conducted based on the current PC/ABS alloys in this thesis. Firstly, the law of influence of the content of short glass fiber on the performance of reinforced PC/ABS was discussed. The result indicated that the strength and elasticity modulus improved as the content of short fiber glass increased, while the impact strength declined significantly. Simultaneously, the viscosity and resistance to heat of reinforced PC/ABS increased. ABSHR and EMA were selected to strengthen the toughness of short glass fiber reinforced PC/ABS as the glass fiber reinforced material was poor in toughness. And the mechanism and effectiveness of two kind of tougheners were systematically studied in macro-performance and microstructure. The result showed that the EMA could improve the impact strength much more and it had better effect on strengthening toughness of short glass fiber reinforced PC/ABS.Phosphate ester compounds, as a type of halogen-free flame retardant, were widely used in PC/ABS and they, without the shortcoming of halogenated flame retardant, released less smoke and poison gas when they burned. In this thesis, three kinds of phosphate ester(TPP, RDP, PX-200) and TPP/RDP compound were adopted to improve the flame retardation of short glass fiber reinforced PC/ABS. The performance change law of short glass fiber reinforced PC/ABS after mixed with phosphate ester flame retardant was studied and the flame retardant mechanism of phosphate ester flame retardant was analyzed. Phosphate ester flame retardant can work in condensed phase and gas phase. The rank of flame retardation can be up to UL94V-0if the addition of TPP and RDP reaches12phr, and the addition of PX-200and TPP/RDP compound reaches1Ophr. The process of extruding and prilling has an important effect on short glass fiber reinforce composites, and thus short glass fiber reinforced PC/ABS with excellent properties can be fabricated by adopting optimized process. Based on plenty of experiments, the law of influence of screw-combining modes, blending temperature, screw speed and feeding modes on performance of short glass fiber reinforced PC/ABS was obtained and according to the law, the optical parameter of processing was determined. In this way, we work out the forming process of short glass fiber reinforced PC/ABS.Modification mechanism and technology of PC/ABS composites was mastered through the research on the performance and extruding process of PC/ABS alloys. On this basis, formulation of blends were repeatedly studied and optimized over and over, and a kind of halogen-free flame retardant short glass fiber reinforced PC/ABS was developed, which had passed the mechanical performance test, drop test of complete machine and freezing test of complete machine taken by Hisense Mould and Plastic Products Co. Ltd. Its performance meets the market demand and it is available for industrial production.