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首页> 外文期刊>Journal of Materials Science >Morphological comparison of isotactic polypropylene molded by water-assisted and conventional injection molding
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Morphological comparison of isotactic polypropylene molded by water-assisted and conventional injection molding

机译：水辅助成型与常规注塑成型等规聚丙烯的形态比较

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It is well known that water-assisted injection molding (WAIM) process can be fulfilled based on the melt filling stage of conventional injection molding (CIM) process. However, due to the different physical fields involved during WAIM and CIM processes, WAIM part should exhibit unique morphological features compared with the CIM one. In this study, isotactic polypropylene (iPP) parts were prepared by WAIM and CIM, respectively, and their comparative study on morphology were therefore carried out by means of polarized optical microscopy (POM) and two-dimensional (2D) wide-angle X-ray diffraction (WAXD). POM observations illustrated that the WAIM part exhibits a "skin-core-water channel" structure, while the CIM part shows a typical "skin- core" structure. 2D-WAXD results showed obvious arclike reflections in each position along thickness direction of the WAIM part, indicating a pronounced molecular orientation. Furthermore, a parent-daughter model (or branched shish-kebab structure) appears at 0 and 100 μm for both the parts, and the fraction of daughter lamellae for WAIM part is lower than that of CIM part. As for the 1D-WAXD curves, it is noticed that there is a very tiny (300) reflection of β-form in the CIM part, while it is invisible in all positions of the WAIM part. In addition, the crystallinity and crystalline size L of CIM part are found to be higher than that of WAIM part. Those results demonstrate that water penetration and rapid cooling rate have a significant effect on the morphological features of WAIM part.
机译：众所周知，可以基于常规注射成型（CIM）工艺的熔融填充阶段来实现水辅助注射成型（WAIM）工艺。但是，由于WAIM和CIM过程涉及不同的物理场，因此WAIM零件与CIM零件相比应表现出独特的形态特征。在这项研究中，分别由WAIM和CIM制备了全同立构聚丙烯（iPP）零件，因此，通过偏光显微镜（POM）和二维（2D）广角X-射线进行了形态比较研究。射线衍射（WAXD）。 POM观察表明，WAIM部分显示出“皮芯-水通道”结构，而CIM部分显示出典型的“皮芯-水通道”结构。 2D-WAXD结果显示沿WAIM零件厚度方向在每个位置都有明显的弧形反射，表明分子取向明显。此外，两个部分的母女模型（或分支的烤肉串结构）均出现在0和100μm处，WAIM部分的子代薄片比例低于CIM部分。对于1D-WAXD曲线，注意到在CIM部分中有非常微小的β反射（300），而在WAIM部分的所有位置都看不到。另外，发现CIM部分的结晶度和晶体尺寸L高于WAIM部分的结晶度和晶体尺寸L。这些结果表明，水的渗透和快速的冷却速度对WAIM零件的形态特征具有重大影响。

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