【作者】 赖礼汇；

【导师】 申开智；

【作者基本信息】 四川大学 ， 材料加工工程， 2006， 硕士

【摘要】 在聚合物成型过程中采用特殊的加工方法，改变聚合物的凝聚态结构，从而改善其性能可以达到优化材料使用和降低生产成本的目的，是高分子材料科学与工程的一个重要研究课题。本论文采用自行研制的振动注射成型装置，在注射和保压阶段对熔体施加低频高压的振动压力，使熔体受到一定的剪切作用，改变聚合物共混物中各组份的取向，结晶形态以及相形态，并且通过熔体冷却固化将应力对共混物微观形态结构的影响冻结下来，进而研究微观形态结构变化对共混物材料宏观力学性能的影响。采用上述方法制备了HDPE/LLDPE、PP/LLDPE和PP/HDPE等几种聚烯烃共混物，研究了振动注射成型聚烯烃及其共混物的取向结构和结晶形态，相形态的变化与力学性能之间的关系。主要研究结果如下： (1)与常规注射成型试样相比，振动注射成型试样的拉伸强度和冲击强度均获得了提高。拉伸强度提高的幅度跟分子链的结构有关，以高度线性分子链结构的HDPE为基体的共混物的拉伸强度提高幅度较大。而以PP和LLDPE为基体的共混物的拉伸强度提高较小。例如HDPE/LLDPE(80/20)振动注射试样的拉伸强度是常规注射试样的2倍左右，而HDPE/LLDPE(20/80)组份经振动注射成型后，拉伸强度仅提高了14.1％。对于PP/HDPE和PP/LLDPE共混体系，振动注射成型使试样的冲击强度得到了大幅度的提高。例如PP/HDPE(60/40)组份的冲击强度提高了294％，PP/LLDPE(80/20)组份冲击强度提高了221％。而且，试验结果表明共混物冲击强度提高的幅度比均聚物提高的幅度更大。更多还原

【Abstract】 A vibration injection molding machine was used to investigate structure and properties of polyolefin blends. The melt was subjected to a low-frequency and high-amplitude vibration pressure during the period of injecting and packing. The orientation, crystallization behavior and phase morphology of the melt can be changed under the shear stress field. All of these alterations would be kept when the melt cooled down. Conventional injection molding and vibration injection molding were used to mold samples of HDPE/LLDPE, PP/LLDPE and PP/HDPE blends. The relationship between mechanical properties and orientation, crystallization behavior and phase morphology was explored. Main results are as following:1) Compared to samples injection molded in conventional way, the tensile strength and notched impact strength of the vibration injection molded samples are improved. The percentage increase of tensile strength is depending on the macromolecular structure. More increase of tensile strength is obtained in blends with HDPE matrix than blends with PP and LLDPE matrix. The reason is that there is less chain branching in HDPE than in PP and LLDPE, it’s easier for HDPE to obtain more orientation under shear stress field. For example, when vibration injection molded, the HDPE/LLDPE (80/20) blend got a 100% increase in tensile strength while the HDPE/LLDPE (20/80) blend just got a 14.1% increase.2) The notched impact properties of PP/HDPE and PP/LLDPE blends are greatly更多还原