Compared with traditional injection foaming, co-injection foaming serves as a method to prepare products with high-quality surfaces and enhanced mechanical properties, demonstrating excellent technical advantages and economic benefits. The effects of high-density polyethylene (HDPE) content, foaming agent content, melting temperature of core material, and nano-organic montmorillonite (OMMT) content on the cell structure, mechanical properties, and crystallization behavior of isotactic polypropylene (iPP)/HDPE composite foam prepared by co-injection foaming were systematically studied. At a foaming agent content of 2 wt.%, HDPE content of 30 wt.%, OMMT content of 3 wt.%, and the melting temperature of core material of 190 °C, the composite foam exhibited a cell size measuring 85 μm, a cell density of 2.5 × 10 cells/cm, a tensile strength of 25.8 MPa, and an impact strength of 12.5 kJ/m. The addition of HDPE reduced the crystallinity of iPP matrix, while enhancing the solubility of carbon dioxide within the matrix. The non-miscible interface between HDPE and iPP helped reduce the energy barrier for cell nucleation. Furthermore, the introduction of OMMT as a nucleating agent in iPP/HDPE composite material dramatically decreased the energy barrier for cell nucleation. These synergistic effects result in foam with the smaller cell size and the higher cell density, exhibiting excellent comprehensive mechanical properties. This work provides a feasible method for preparing composite foam with excellent comprehensive performance.

中文翻译：

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工艺条件和纳米填料对共注塑聚丙烯-聚乙烯复合材料泡孔结构和力学性能的影响

与传统注射发泡相比，共注射发泡可以制备出具有高质量表面和增强机械性能的产品，表现出优异的技术优势和经济效益。高密度聚乙烯(HDPE)含量、发泡剂含量、芯材熔融温度、纳米有机蒙脱石(OMMT)含量对等规聚丙烯(iPP)/HDPE泡孔结构、力学性能和结晶行为的影响对共注射发泡制备复合泡沫材料进行了系统研究。当发泡剂含量为2wt.%、HDPE含量为30wt.%、OMMT含量为3wt.%、芯材熔融温度为190℃时，复合泡沫的泡孔尺寸为85μm，泡孔密度为2.5×10个泡孔/cm，拉伸强度为25.8MPa，冲击强度为12.5kJ/m。 HDPE 的添加降低了 iPP 基质的结晶度，同时增强了基质内二氧化碳的溶解度。 HDPE 和 iPP 之间的非混溶界面有助于降低细胞成核的能垒。此外，在 iPP/HDPE 复合材料中引入 OMMT 作为成核剂，大大降低了泡孔成核的能垒。这些协同效应使得泡沫具有更小的泡孔尺寸和更高的泡孔密度，表现出优异的综合机械性能。该工作为制备综合性能优良的复合泡沫提供了一种可行的方法。