Foaming of polypropylene by using both chemical and physical blowing agents. A comparative study of the structure and physical properties

Abstract

Microcellular foams have focused attention of researches due to improvement in some properties when compared to conventional foams. Several production routes for these materials have been developed although most of them are based in the use of physical blowing agents. In this paper a collection of polypropylene foams with relative densities in the range of 0.25-0.60 and cells sizes in the microcellular range are produced by using the improved compression moulding technique developed at CellMat laboratory. Moreover, several polypropilene foams with similar densities have been produced using CO2 as blowing agent by applying the pressure quench method in a autoclave. The effect of chemical composition type of foaming process and processing parameters on the cellular structure and mechanical properties in compression are analysed for these wide collection of foams.