Effect of Nominal Laminate Thickness on Consolidation Quality and Tensile Properties of Compression‐Molded Polyetherketoneketone/Carbon Fiber Composites

ABSTRACT

Carbon‐fiber‐reinforced thermoplastic composites have attracted growing attention as high‐performance structural materials due to their superior toughness, shorter processing cycles, and recyclability. However, manufacturer‐specified consolidated ply thickness defined under autoclave conditions cannot be translated directly into compression molding, where localized pressure gradients and lateral material flows govern the consolidation. To address this issue, 16‐ply quasi‐isotropic carbon fiber/polyetherketoneketone laminates ([45°/0°/−45°/90°] _2s ) were fabricated via picture‐frame‐assisted compression molding (380°C, 1 MPa) in this study, and three cavity thickness conditions (under‐designed, 2.00 mm; nominal, 2.24 mm; and over‐designed, 2.50 mm) were evaluated using a confocal laser thickness gauge, ultrasonic C‐scan, optical microscopy, and tensile testing (ASTM D3039). The cavity thickness governed the consolidation quality across all conditions. No voids were observed within the examined micrographs for the 2.00 mm condition, which also yielded the highest tensile strength, while the 2.50 mm condition produced macrovoids, interlaminar delamination, and an 8.6% strength reduction. These findings demonstrate that autoclave‐derived CPT values cannot be directly applied to compression mold design, where local pressure gradients, lateral material flow, and cavity constraint govern consolidation outcomes differently from autoclave processing, and identify 2.00–2.24 mm as a preliminary consolidation window under the present material, tooling, and processing conditions.