| In recent years, many new methods such as blending, copolymer, filling, reinforce, have been adapted to prepare new materials, instead of synthesizing new polymer. The study of nylon/polyolefin composite is flourishing. Nylon/polyolefin barrier material has been one of important objects, because of its applications widely, low cost, great needs in packaging industry and automobile industry.Barrier property depends on the morphology of disperse phase in blends strongly. When disperse phase becomes the morphology of slices parallelling, this make the molecule permeated to travel longer path length, so barrier property is improved. Nylon and polyolefin are immiscible polymers. In processing it is difficult to form layers because of high interfacial tension, low adhesive strength at interface. In addition, the viscosity of nylon must be higher than that of matrix in order to get layer structure. The high viscosity ratio between nylon and polyolefin is in favor of not only forming large phase dimensions, but also getting layers.In the study of compatibilizer, it was studied that the maleic anhydride was grafted onto POE and PE by reactive extrusion. The effect of maleic anhydride and DCP added on graft efficiency and melt index .mutual effect of MAH and DCP, the effect of inhibitor added on graft efficiency and melt index were investigated. Moreover, the microcosmic mechanism was discussed. With DCP added, melt index decreases and graft efficiency increases contrarily, then increase gently. The optimal amount of DCP is 0.20wt%. With maleic anhydride added, graft efficiency and melt index increases rapidly to some extent, then decreases. The study of mutual effect of maleic anhydride and DCP shows that mutual effect is not obvious at low content of MAH and DCP, and that it is important at high content of MAH and DCP. Graft efficiencyof POE was improved greatly by introduce propylene, and that HDPE didn' t.In the study of nylon extended, two chain extenders, diisocyanate and bisoxzoline, were used to extend polyamide. The effect of the chain extender added, temperature, the screw speed on the intrinsic viscosity, end groups content, crystalline were studied. The modified nylon was characterized by differential scanning calorimetry and polarizing microscope. Intrinsic viscosity of modified nylon raised from 0. 92 × 100ml/g to 1. 36 × 100ml/g by extender of MDI and from 0. 92 × 100ml/g to 1. 23 × 100ml/g by the extender of BOZ respectively. They are all effective extenders. The best outcome can reach when the amount of the extenders is between one time and two times of ideal amount. The optimal processing condition of MDI are 240℃ and 30rpm and those of BOZ are 240℃ 110rpm. After modified, melt point and supercooling degree of the nylon decrease, otherwise crystalline temperature and crystallinity increase. At the same time, nylon modified possesses better crystalline morphology by polarizing microscope.In the study of barrier material, the compatibilizer of polyolefin grafted with maleic anhydride and high viscosity nylon above-mentioned were adapted to prepare nylon barrier material by two screw extruder. The morphology of HDPE/PA blends was observed by SEM. The barrier property was characterized by method of loosing weight. The effect of composite, compatibilizer, processing conditions on morphology and barrier property of nylon barrier material were studied. The result show that the layer structure come into being in the blend of HDPE/PA, specially when the weight amount of nylon is between 25% and 40% high ratio of length and thickness was obtain, at the same time barrier property of the blends was improved greatly. If processing temperature is 240℃ and screw speed is 100rpm, the best layer structure and barrier property of blend can be received.In this paper, the barrier material of HDPE/PA was investigated from modifying polymer and optimizing process conditions. The study provides the basis for improving properties of blend and designing process conditions to obtain expected morphology and properties of pol... |
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