Study On Polyolefin Modified By Blending,nanometer Particle Compounding And Short Fiber Reinforcing

STUDY ON POLYOLEFIN MODIFIED BY BLENDING, NANOMETER PARTICLE COMPOUNDING AND SHORT FIBER REINFORCINGABSTRACTThis dissertation studies the modification of polyolefin by reactive blending, nanometer particle compounding and short fiber reinforcing .Maleic anhydride (MAH) and trially isocyanurate (TAIC) are employed to act as the reactive compatibilizers for PP/ABS, PP/PBT, PP/PA6 blends prepared by one-step reactive extrusion technology. The research work is concentrated on the grafting and crosslinking copolymerizations of MAH, TAIC with PP and ABS, and characterization of the products. Mechanical and processing property tests of PP/ABS, PP/PBT, PP/PA6 blends compatibilized by MAH and TAIC have also been carried out. Furthermore, Phase-contrast microscopy, SEM, Polarmicroscopy, and DSC analysis are used to indicate the morphology, fracture mechanism, crystallization behavior of the blends. The results show that the dicumyl peroxide (DCP) will result in the degradation of PP, hence, its content in the system should be controlled. TAIC could restrain the degradation of PP for PP/ABS, PP/PBT, PP/PA6 reactive blending, and avoid the weakening of the mechanical property. In PP/ABS blends, the dispersed ABS phase can make the PP crystallinity and melt point decrease via reducing the crystal dimension. Addition of MAH and TAIC will strengthen such a effect. Mechanical property characterization and theology analysis indicate that the one-step reactive extrusion is a quite good technology for the commercial use of PP/ABS blend. In PP/PBT blends, PBT can improve the mechanical property by fiber-reinforcing mechanism, and MAH will promote the PP crystallization. TAIC is much better than MAH for PP/PA6 reactive compatibilizing blending in mechanical and processing properties. In PP/PA6 blends, TAIC will make the PA6 crosslink, so the residues of TAIC and initiator should be excluded from the blends by two-screw extruder configuration designs.Elastomers of EPDM, POE, nanometer particles of CaCOs, ZnO, TiOi and superfine talc are quite good modifiers for PP. Among of above modifiers, POE is better than EPDM for PP toughening, superfine talc is more suitable for PP/EPDM reinforcing than for PP/POE system. Nano-TiO2 can make better effect of modification for PP/EPDM (POE) than nano-ZnO. Nano-ZnO and nano-TiO2 will disperse in the matrixes of copolymerized PP and homopolymerized PP in the scale of nanometer by one-step melt extrusion. The PP composites prepared by elastomer and nano-meter particle modification can be used as the water-supply pipes and joints according to the standards of the correspond products.TAIC can copolymerize with styrene initiated by DCP and BPO to prepare the copolymer of P(St-Co-TAIC) by suspension polymerization method. The product has been proved by IR, TG (DIG) and solubility analysis. P(St-Co-TAIC) can make a good compatibilizing role in incompatible blends of PS/PC, PS/PVC. All of these blends show good clarity.TAIC can also graft with PS initiated with DCP, its grafting ratio will be increased with increasing of the TAIC contents. MBS is more effective than TAIC for PS/PC reactive compatibilizing blends. Nano-SiOj can take better role of modification for PS/EVA/PC blend than PS/PC and PS/PS-g-TAIC/PC system.For the composites of short glass fiber reinforced injection-moulded Polypropylene (GF/PP) and short carbon fiber reinforced injection-moulded Polyetherether Ketone (CF/PEEK) , the results show that the fiber orientation exists in "skin and core layer" structures in the injection plate. The thickness of skin and core layers can be characterized by metallographic optical microscope. GF can improve the tensile strength of PP, but the impact strength, break elongation and melt flow rate (MFR) decreased with increasing of GF contents in GF/PP composites. Orientation degree of GF in skin and core layers is promoted with increasing of injection pressures. The crystallizing ability of PP in GF/PP composites goes down with increasing of GF contents by polarmicroscopy. Up to 40%...