Extruded Open-Cell Foams Using Two Semicrystalline Polymers with Different Crystallization Temperatures

This paper presents an extrusion-based open-cell foaming process with polypropylene (PP)/polyethylene (PE) blends. The basic strategy for achieving a high open-cell content is to induce a hard/soft melt structure using two semicrystalline polymers with distinctively different crystallization temperatures (Tc) and to foam this inhomogeneous melt structure with supercritical CO2. The effects of polymer blending, die geometry, and temperature on cell opening were investigated in this study. Two blends of high-melt-strength (HMS) PP/metallocene PE (mPE) and linear PP/low-density PE (LDPE) were used as case examples.