Thermoplastic RTM – RTMPLAST

The proposal comes from the growing interest for thermoplastic composite materials including high performance ones in the aeronautic field. It is an anticipation of industry needs for this type of composite in the coming years compared to thermosetting matrix composites. It also has a strong economic potential in sectors where parts are widely produced as long as the manufacturing cost is reasonable and the pace is high.
This project aims to achieve a thermoplastic composite piece with continuous fibers in one step manufacturing (using RTM process) where polymer matrix and composite part are designed in the same self-working mold. This is an alternative to thermosetting matrix composites with an undeniable ecological interest and important in terms of assembly (welding) and recycling. It aims to develop a new process controlled by the thermo-mechanics to control the cycle times (varying from one application to another: from several minutes to an hour).
Several original early-stage work have to be done. The optimization of the process cycle requests an accurate knowledge of physical and chemical phenomena in both the filling phase of the mold and the consolidation phase to model them correctly. It also requires the development of physical and chemical characterization methods and devices of resins, reinforcements at all stages of in situ polymerization development.
The filling phase is a delicate issue. Numerically, we propose to locally describe the rheology of matter coupled to heat and mass transfers and its transformation with a numerical suitable scheme. The computation times should be reasonable and the developed code must ultimately describe the macroscopic behavior of the matrix. It will also include the thermal control of the consolidation phase during which the crystallization of the matrix and the shrinkage occurs and therefore the properties of the part.
From a thermal point of view, the challenge is to characterize experimentally the heat transfers in order to use them as a monitoring tool of the saturation of the reinforcement during the flow, with consideration of thermal dispersion phenomena. This characterization involves the determination of the thermal conductivity tensor. The monitoring of saturation via the thermal conductivity tensor is original and could lead to important advances in the field of modeling of the reinforcements permeability.
In terms of materials, we aim to develop a new oligomer which the in situ polymerization will lead to the synthesis of thermostable macromolecules of PEKK-type polymer. It represents a challenge in terms of chemistry considering the complexity of the usual synthesis conditions for such high performance polymers (in the case of PEKK, the Friedel / Kraft type chemistry is clearly not feasible for the RTM process).