Sheet extrusion and thermoforming of discrete long glass fibre reinforced polypropylene

The present paper summarizes the main aspects and the developments in sheet extrusion and thermoforming of discrete long glass fibre (LGF) composites using the SAFIRE (Self Assembling Fibre Reinforcement) technology. During extrusion the long glass fibres are organized into coherent fibre mats which persist into the solid state, and are able to withstand the deformation process that takes place during thermoforming. A process analysis has been performed for extrusion and thermoforming indicating the main individual operations. Both processes have been studied with regard to their performance with the materials used in the studies, namely polypropylene homo- and copolymer, with and without LGF reinforcement. Significant improvements in mechanical properties relative to the unreinforced materials have been found for the extruded sheets and the thermoformed products. Major improvements in processability relative to unreinforced PP have been found for the LGF materials. These are discussed in terms of the coherent fibre mat concept.