PROCESSING OF CF PEEK THERMOPLASTIC COMPOSITES FROM FLEXIBLE PREFORMS/

Commingled yarns and powder/sheath fibre bundles are two flexible ther moplastic composite preforms, consisting of a blended combination of r einforcing fibre yarn (e.g. carbon fibres) and a yarn spun from a ther moplastic resin or a polymer resin powder respectively. These preforms can be used as basic filament yarns that can be interwoven, braided o r knitted for making two- or three-dimensional composite parts. Commin gled 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 me lts, thus wetting the reinforcing fibres and forming a thermoplastic r esin 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 prope rties of CF/PEEK commingled yarn and powder/sheath fibre bundle compos ites are highlighted.