Continuous Consolidation of Polypropylene/Glass Fibre Commingled Fabric

Abstract

Continuous consolidation of a polypropylene/glass fibre commingled fabric has been investigated using the roll forming process. For this manufacturing process, unconsolidated heated plies are progressively consolidated by passing through a series of rollers. First, compaction trials (performed to determine the most suitable processing parameters) have shown that the repeated application and release of pressure can significantly improve the level of consolidation by allowing trapped air to escape from the molten resin. The influence of the roller gaps, laminate temperature and processing speed has then been determined for the roll forming process. Quality of consolidation was assessed by observing polished micrographs of cross-sections and by determining the void content and flexural properties. Results showed that a roll gap sequence starting at 50% of the unconsolidated laminate thickness is satisfactory. For smaller roller gaps, results have shown that the fabric structure is altered by the squeezing flow of the resin. Results also showed that materials with high inlet temperatures and low process speeds have better levels of consolidation due to lower matrix viscosity and longer contact time with the rollers. Using optimum process parameters, continuous consolidation of 4 plies of 1485 g/m2 fabric at a rate of 0.5 m/min led to a satisfying quality of composite, with less than 4% void content.