Interest of a Rheokinetic Study for the Development of Thermoplastic Composites by T-RTM

Abstract

Until today, thermosetting polymer based composites were predominant, but are faced with environmental rules more stringent (COV, recyclability...). Thermoplastic composites are a good answer to the evolution of environmental rules, and have an increased need due to their improved properties compared to thermosets. One thermoplastic process route offered is the injection of monomers with a low viscosity (around 10mPa.s): Thermoplastic-Resin Transfer Molding (T-RTM). Currently, reactive thermoplastics are not technically matured for industrial applications. Indeed, their chemistry and rheology especially in the presence of fibers are not well studied and understood. The reaction time is the most crucial parameter for a well-controlled injection and the viscosity should stay low until full impregnation is achieved. The other point is the reaction kinetics. The faster the reaction, the more reaction heat is released in less time which results in overheating in the center of very thick parts. In a first approach the pure polymer is investigated. To better understand the reaction time during an injection process, rheological measurements were achieved at different shear rates and temperatures. In parallel, the reaction kinetics through the exothermic reaction during polymerization are modelled and experimentally verified.