Affiliation: | 1. National Engineering Research Center for Advanced Polymer Processing Technology, The Key Laboratory of Advanced Materials Processing & Mold of Ministry of Education, Zhengzhou University, Zhengzhou, China
Contribution: Conceptualization (lead), Data curation (lead), Formal analysis (lead), ?Investigation (lead), Writing - original draft (lead);2. National Engineering Research Center for Advanced Polymer Processing Technology, The Key Laboratory of Advanced Materials Processing & Mold of Ministry of Education, Zhengzhou University, Zhengzhou, China
Contribution: Data curation (supporting), ?Investigation (equal);3. National Engineering Research Center for Advanced Polymer Processing Technology, The Key Laboratory of Advanced Materials Processing & Mold of Ministry of Education, Zhengzhou University, Zhengzhou, China;4. Ningbo Shuanglin Auto Parts Co., Ltd, Ningbo, China
Contribution: Supervision (equal);5. Ningbo Shuanglin Auto Parts Co., Ltd, Ningbo, China
Contribution: Supervision (lead);6. National Engineering Research Center for Advanced Polymer Processing Technology, The Key Laboratory of Advanced Materials Processing & Mold of Ministry of Education, Zhengzhou University, Zhengzhou, China
Contribution: Methodology (lead), Resources (lead);7. National Engineering Research Center for Advanced Polymer Processing Technology, The Key Laboratory of Advanced Materials Processing & Mold of Ministry of Education, Zhengzhou University, Zhengzhou, China
Contribution: Methodology (equal), Resources (lead) |
Abstract: | Injection molding products made of aluminum flakes and polymer blends exhibit a distinctive esthetic effect. However, during the filling process, the melt flows in different directions converge and collide, resulting in the flop effect of the aluminum flake and consequent weld line formation. Herein, microcellular injection molding (MIM) was employed to fabricate polypropylene/aluminum flakes (PP/Al) composite foamed parts with distinct weld lines using supercritical nitrogen (scN2) as the physical blowing agent. The scN2 content has a significant effect on cell diameter and cell density. When the scN2 content was 0.6%, the weld line width of the foamed part was 13.03 μm, while it was 30.41 μm for the solid counterpart due to the expansion and rupture of cells in the flow front during filling. Moreover, the orientation of Al flakes was mostly along the flow direction for the foamed parts, while it was generally aligned perpendicular to the flow direction for solid parts in the weld line region. In addition, the flexural modulus of foamed parts was increased by 29% compared with the solid parts, although the tensile strength was reduced by 18% due to the alignment of Al flakes and the stress concentration on the cell walls. Therefore, this work provides insight into the improvement of flexural property and the mitigation of weld lines for injection molded composite parts using MIM. |