溢流槽对HDPE微制品结构和力学性能的影响

Effect of Over-flow Cavity on the Structure and Mechanical Properties of High Density Polyethylene Microparts

通过在微注塑模具型腔末端增设溢流槽,提高了高密度聚乙烯(HDPE)熔体在充填过程中的剪切速率。利用Moldflow软件对熔体在两种不同构造模具中的充填行为进行模拟,验证了增设溢流槽对于提高剪切速率的可行性;采用差示扫描量热仪(DSC)、显微偏振红外和拉伸试验对制品的微观结构和力学性能进行了表征。结果表明:溢流槽有助于提高制品的结晶度和制品剪切层分子链的取向度,从而使其具有更高的拉伸强度。

The shear rate of high density polyethylene （HDPE） melt has been improved in the filling process by introducing an over-flow cavity into the end of the microinjection mold. Moldflow simulation of the filling process of the melt in the two molds with different structures verifies that the shear rate can be improved by introducing over-flow cavity. The microstructure and mechanical properties of HDPE parts were characterized by differential scanning calorimetry （DSC）,microscopic polarized infrared and tensile test. The results showed that the over-flow cavity contributed to improving the crystallinity and orientation degree of the molecular chain in shear region of the parts, thereby leading to the increase of tensile strength.