高强超韧高密度聚乙烯/聚丙烯共混物性能与微相分离结构的研究  

THE HIGH MECHANICAL PROPERTIES AND MICRO-PHASE SEPARATION OF HIGH DENSITY POLYETHYLENE AND POLYPROPYLENE BLENDS

作　　者：张弓[1] 傅强[1] 申开智[1] 蒋龙[1] 

机构地区：[1]四川大学高分子材料科学与工程系,成都610065

出　　处：《高分子学报》2000年第3期306-310,共5页Acta Polymerica Sinica

基　　金：国家自然科学基金!(基金号 5 9773 0 2 5 );香港蒋氏工业慈善基金!(基金号RC9610 5 )

摘　　要：在常规注射过程中 ,难以获得超高性能的共混体系注射制件 ,已有的研究表明 ,采用高剪切注射 ,可以抬高共混体系的最低临界相容温度曲线 (LCST)的位置 ,增加相容性 .当熔体进入模具后 ,冷却的同时相容性下降 ,开始相分离 ,相分离程度发展到某一程度即可获得高性能的制件 .对于高密度聚乙烯 (HDPE)、聚丙烯 (PP)两组分均为结晶型聚合物的共混体系 ,由于其相形态与结晶形态相互制约、竞争 ,微相分离程度难以控制 ,因此对其液 液相形态与结晶过程的控制是获得共混物最终形态与性能的关键 .采用振动保压注射成型技术不仅对HDPE、PP各自力学性能有明显的自增强作用 ,而且对HDPE/PP共混体系的力学性能也有十分明显的改善 .DSC、WAXD、SEM结果表明共混体系拉伸强度的提高主要取决于试样中串晶数量和大分子链的定向程度 ,而冲击强度则主要取决于两组分微观的相分离程度 .研究结果表明 ,HDPE/PP含量为 92 / 8的试样拉伸强度为 97 1MPa,80 / 2 0试样的缺口冲击强度为 4 5 5kJ/m2 ,较静态试样分别提高 4 3倍和 9 5倍 .采用振动填充注射技术针对某一组分可以获得高强度、高韧性的共混制件 .The improvement of mechanical properties of high\|density polyethylene (HDPE) and polypropylene (PP) blends was studied by controlling the phase compatibility versus phase separation.In the original injection molding processes,super mechanical properties of blend specimens have not been got easily.Researches have been carried out in injection molding with high shear injection conditions.It has been pointed out that the compatibility of blends will increase under the strong shear in injection processes due to the raise of LCST curve.After the melt is injected into the cold mold,its temperature and compatibility decrease simultaneously,phase separation takes place and becomes frozen in the specimen.High mechanical properties will be got when the phase separation develope to some extent,but it is difficult to control the phase compatibility and separation.The special method of oscillating packing injection molding under low pressure provides a condition to control the phase separation degree.Because the phase morphology and crystal morphology of HDPE/PP blends compete with each other,it is difficult to control the micro\|phase separation.In this paper, the fine struture combined with the micro\|phase separation and orientation were controlled by using that special injection method and high strength and high toughness blends were obtained.DSC and WAXD results indicate that the improvement of tensile strength is dependent on the number of shish\|kebab crystals and the degree of macromolecule orientation caused by the oscillating packing injection molding.SEM results indicate that the impact strength is dependent on the degree of macro\| and micro\|phase separation.The high tensile strength 97 1MPa and high toughness 45 5kJ/m\+2 of HDPE/PP blends were achieved when the PP content in the blends was 8% and 20%,respectively.Which are 4 3 times and 9 5 times as high as the corresponding values of their static specimens respectively.The future work will be carried out to investigate the phase morphology and crystal morp

关 键 词：振动填充注射 聚乙烯 聚丙烯 共混物 性能 结构 

分 类 号：O632[理学—高分子化学]