Thermoplastic as carrier for delivering carbon nanotubes and layered clay in epoxy resin for composite applications

(eng) Thermoplastic and nanofiller additives have already shown their potential benefit on mechanical, thermal or electrical properties of composites. An original method to incorporate simultaneously a thermoplastic phase and nanoparticles in laminates processed by resin transfer molding is proposed in the present study. Introduction of nanocomposite prepared by melt blending in the dry composite preform intends to deliver both additives in the thermoset matrix during the process. This thesis investigates the concept to determine if a soluble thermoplastic can be exploited to disperse and distribute nanofillers in epoxy resin and understand the key parameters controlling the mechanism. First, this work focuses on solubility of poly(ether sulfone) and phenoxy in epoxide and diamine precursors and in reactive formulations like RTM6 resin qualified for aeronautics. Composition gradients and microstructures induced by these thermoplastics in epoxy resin are also detailed. Then, the second part of the study demonstrates that nanocomposite filaments prepared with unmodified multiwalled carbon nanotubes or organomodified layered clay allow to distribute both thermoplastic and nanofillers in epoxy resin. Interdiffusion occurring during thermal treatment leads to thermoplastic swelling by the resin precursors. Identical distribution profiles evidenced for thermoplastic and nanofillers in the resin shows that these amorphous polymers act as carriers for delivery of nanoparticles into epoxy resin. Once reaction induced phase separation takes place, a microstructure gradient is generated with, locally, thermoplastic nodules and nanofillers being dispersed in the epoxy resin continuous phase.