Abstract
Commingled yarns and powder/sheath fibre bundles are two flexible thermoplastic composite preforms, consisting of a blended combination of reinforcing fibre yarn (e.g. carbon fibres) and a yarn spun from a thermoplastic resin or a polymer resin powder respectively. These preforms can be used as basic filament yarns that can be interwoven, braided or knitted for making two- or three-dimensional composite parts. Commingled yarns and powder/sheath fibre bundles retain the flexibility of a tow such that when a fabric is woven from these materials, the fabric can be designed to be highly conformable and drapeable. When heat and pressure are then applied, the thermoplastic yarn or powder/sheath melts, thus wetting the reinforcing fibres and forming a thermoplastic resin binder. In the subsequent cooling step, the system is transformed into a rigid composite material. In this paper, major achievements in the study of the fundamental mechanisms which govern the impregnation process, the consolidation quality and the resulting mechanical properties of CF/PEEK commingled yarn and powder/sheath fibre bundle composites are highlighted.