高密度聚乙烯材料的注塑自增强工艺研究

本工作研究了在注塑机上进行体型聚乙烯试样的自增强成型工艺,探讨了自增强效果与注塑工艺之间的关系。 试验材料的自增强效果强烈地依赖于熔体的流动条件。在一个低熔体温度的范围内,发现有一个对应最大自增强效果的注塑温度。自增强效果随注塑压力的升高而增强。注塑速度和模具温度对自增强效果的影响很小。在其他可以类比的工艺条件下,试样的力学性能依试样形状的不同,表现出极不同的结果。

SELF-REINFORCEMENT OF THE HIGH DENSITY POLYETHYLENESBY INJECTION MOLDING

In this paper the self-reinforcement of the semicristalline polyethylenes by injection molding is presented and discussed. The increasement of the stiffness and strength changes with the parameters of the injection molding, the most notable being the geometrical boundary conditions for melt flow, melt temperature and holding pressure, other parameters, such as the injection velocity and the mold temperature have a clearly less influence. By the correlation between the melt temperature and the tensile strength a pronounced peak is registed, the position of the peak depends upon the cross section of the samples. The mechanical properties as a function of the holding pressure indicate a linear dependence. The maximal tensile strength is achieved in the bars with the small cross section and ca-rity volume.