Influence of consolidation process on voids and mechanical properties of powdered and commingled carbon/PPS laminates

Abstract : Relations between autoclave consolidation process, microstructure and mechanical properties of thermoplastic composite laminates were investigated. For this purpose, two different carbon fibers/PPS semi-pregs were used for laminate manufacturing: a powdered fabric and a commingled fabric with stretch broken fibers. Laminates with stacking sequence were consolidated in autoclave. Several consolidation levels were established by varying process parameters which are external pressure, vacuum level and consolidation duration. Microstructural characterization was performed by using matrix digestion and CT-scanning to identify void content and morphology. Laminate mechanical properties in tensile, bending, compressive and interlaminar shear were also assessed. External pressure increase by 0.5 MPa leads to void content reduction of 2.1% for powdered system and for commingled system. The rising consolidation duration contributes slightly to void content decrease. Bending and interlaminar failure stress are the most sensitive to void level with a dependency on void size and location. Results acquired allow to identify main settings for optimized consolidation cycles which could be used for thermoplastic composite part manufacturing with complex shape.