熔体温度对注塑成型iPP制品结晶形态的影响

注塑成型聚丙烯制品的内部结晶形态对制品的最终性能起着至关重要的作用,而结晶形态的形成对成型条件(尤其是熔体温度)有一定依赖性。文中利用偏光显微镜、小角X射线散射和广角X射线衍射等实验方法,详细研究了熔体温度对注塑成型iPP制品结晶形态的影响。研究结果表明,在实验温度范围内,制品厚度方向形态呈现五层皮芯结构,即冷冻层、过渡层、剪切层、β晶层、α球晶层。随着熔体温度提高,皮层厚度减小;结晶度提高,取向度极大值并无明显变化。

Influence of Melt Temperature on the Morphology Evolution of Injection Molded Isotactic Polypropylene Parts

For injection molding of isotactic polypropylene(iPP) products,the internal crystalline morphology plays a major role in the final properties,and the formation of the crystalline morphology depends on the molding conditions,especially on melt temperature.In this work,the effects of melt temperature on the morphology evolution of iPP parts are analyzed using different experimental techniques (optical,small angle X-ray scattering and wide angle X-ray diffraction analysis).The results show that the thickness of the parts consist of five-layer skin-core morphology,e.g.frozen layer,transition layer,shear layer,β-phase crystallites layer andα-phase crystallites layer.The skin thickness(including frozen layer,transition layer and shear layer) decreases as the melt temperature increases from 210 ℃ to 250 ℃.The maximum degree of orientation does not change obviously.The crystallinity increases slightly with the melt temperature increasing.