Foamed polypropylene for industrial applications

Abstract

There is a great deal of industrial interest in the development of increasingly lighter materials based on polymer foams with improved specific properties for the most varied purposes, from flexible foams for packaging to rigid ones for structural applications. Due to its good combination of properties and reduced cost, foamed polypropylene (PP) could come as a good option. Depending on the base material, foam density and developed cellular structure and microstructure, PP foams may cover a wide range of characteristics and properties wich, combined with the incorporation of functional fillers, could ultimately result in the development of multifunctional lightweight materials. This chapter presents a review of the most recent developments in polypropylene foams, starting out by the commercially available PP grades thought out for foaming applications, the different types of PP-based foams depending on their characteristics and final uses, from low-density flexible foams for cushioning and packaging to medium-high density foams for structural purposes, and the main industrial foaming processes, going from melt-like foaming to solid state chemical and physical foaming. Recent developments in the field of PP foams are also considered, focusing on the combination of cellular structure control via foaming and the incorporation of micro and nanosized functional fillers, with the ultimate objective of developing PP-based foams with a wide range of properties and unique characteristics, from electrically conductive foams through the incorporation of conductive carbon-based nanofillers to foams with direction-dependent transport properties.