Preparation of mold temperature‐insensitive PP/LDPE foaming blends with lightweight and stable foaming performance

Abstract Earlier research has demonstrated that the performance of foamed materials is heavily dependent on their foaming quality. In the process of injection molding foaming, changes in mold temperature frequently exert a significant influence on foaming quality. Consequently, it is essential to develop foaming materials that exhibit insensitivity to mold temperature. In this paper, mold temperature‐insensitive polypropylene/low density polyethylene (PP/LDPE) blends were prepared and chemically foamed at different mold temperatures. The study investigated cell morphology, rheological properties, crystallization characteristics, and mechanical performance of these blends. The findings revealed that PP30LDPE70(f) exhibited superior foaming quality compared to other blends across all tested mold temperatures. Specifically, PP30LDPE70(f)‐T60 showed a better foaming quality and mechanical properties. The cell density was 1.64 × 10 7 cells/m 3 , and the mean cell size was 17.69 μm. The foaming quality deteriorated as mold temperature increased. However, due to its diminished sensitivity to changes in mold temperature, PP30LDPE70(f) displayed a smaller variation in foaming quality. The molecular chain entanglement of PP30LDPE70 was particularly pronounced, resulting in a viscosity that remained relatively constant across varying cooling rates, demonstrating the insensitivity between foaming behavior and mold temperature. Highlights A PP/LDPE blend with viscosity independent of cooling rate was prepared. PP/LDPE foam was prepared by chemical foaming at different mold temperatures. Materials with similar viscosity had better foaming quality. The molecular chain entanglement in PP/LDPE blends was evaluated.