NEAR ZERO-WASTE MANUFACTURING OF CARBON FIBER-REINFORCED THERMOPLASTIC COMPOSITES

Organosheet composite scrap made from polyphenylene sulfide reinforced with long recycled carbon fibers was reprocessed to produce compression molding compounds. No additional polymer was added to the process, making this a demonstration of closed-loop recyclability in composites manufacturing. The recyclate, produced by hammer-milling organosheet trimmings, was sieved and the resulting particulate geometry was measured to predict the fiber length in the molded composites. Tensile testing of the composites revealed that high stiffness parts (tensile modulus greater than 13 GPa) can be achieved using particulate molding compounds, but that tensile strength was significantly degraded. Still, the isotropic molded composites exhibited a greater than 18.8% increase in tensile strength over the neat polymer. Evaluation of the composite microstructure via optical microscopy revealed that fiber packing played a significant role in the tensile strength of the particulate composites, indicating that microstructural heterogeneity should be avoided to maximize the properties of composites made of recycled organosheet waste.