Effect of Fiber Volume Fraction and Material Homogeneity on the Mechanical Performance of Recycled Woven Thermoplastic Composites

This study investigates the effect of fiber volume fraction (FVF) and material homogeneity on the mechanical performance of recycled woven thermoplastic composites. Recycling thermoplastic composites (TPCs) offers advantages over thermoset composites by enabling complete material recycling through melting and reshaping. The research utilized shredded 8-ply Toray Cetex 1100 C/PPS
5 harness satin woven composite mixed with neat PPS polymer at various ratios to achieve target FVFs of 16%, 20%, 25%, and 50%.

Processing was conducted using an internal mixer followed by compression molding into plates. Microstructural characterization was performed using optical microscopy and image analysis to quantify fiber volume fraction distribution and fiber bundle size. Samples were mechanically tested under tensile loading conditions.

Results demonstrate that dilution and mixing significantly improve fiber dispersion compared to unmixed material. The 50% FVF unmixed sample exhibited high stiffness but poor strength and ductility due to large undispersed fiber bundles. Lower FVF samples (16-25%) showed improved dispersion and
mechanical performance, though with varying degrees of scatter. The 20% FVF sample demonstrated optimal balance of properties with good dispersion and reduced bundle sizes.

Image analysis successfully correlated microstructural features with mechanical performance, revealing that bundle size distribution and local FVF variations are critical factors affecting material strength. The study provides insights for optimizing recycling processes of aerospace-grade thermoplastic composites.