Experimental investigation of compression molding of glass/PP-PP foam core sandwich components

Compression molding of sandwich components made from a novel material combination, glass/polypropylene faces and expanded polypropylene foam core, has been experimentally investigated. The aim of the study was to determine the processing window for this material concept in terms of shear, transverse tensile and flexural properties of compression molded components and to evaluate the concept's processability. To enable evaluation of the influence of a large number of process parameters, the components were manufactured according to a two-level Taguchi experimental design. It is found in the study that the compatibility between faces and core results in a face-core bond strength that is always higher than that of the core, provided that the faces remain melted when placed onto the core. All the mechanical properties studied are generally improved by reduced molding pressure and time, while excessive heating of the faces significantly increases their void content and thereby reduces their strength.