Understanding Melt Rheology and Foamability of Polypropylene-based TPO Blends

Rubber-toughened polypropylene (PP) is an important resin for many engineering applications. Through the structural foaming of materials, material cost-saving and lightweight structures can be achieved. In this study, physical blends of PP and poly(ethylene/octene) at various compositions were characterized for their melt strength and shear viscosity. The high pressure MuCell ® foaming process was used to obtain structural foams with average cell diameters of <50 μm and cell densities of approximately 8 million cells/cm 3 . This study presents key understandings between material rheology and its suitability for structural foaming that are in turn linked to blend composition and melt temperature.