During the manufacturing and development of a proof-of-concept prototype of a continuous fiber polyphenylene sulfide (PPS) composite vehicle component, unexpected results were observed in thick laminates of an E-glass-fiber-reinforced PPS matrix, which utilized carbon black as a colorant (GF/PPS+CB). Extensive interlaminar macrocracking, transverse intralaminar microcracking, and micro-/macrovoids were observed in GF/PPS+CB laminates after compression forming. When processed under identical conditions, no micro-/macrocracking or voids were present in GF/PPS laminates and carbon fiber/PPS laminates without carbon black colorant. These observations prompted further investigation into the influence of processing conditions, presence of colorant, mold design (open and closed molds), and geometry (flat and curved) on the development of matrix defects in thick continuous fiber-reinforced PPS laminates.

The effects of ultraviolet (UV) light and moisture environments on the properties of continuous fiber-reinforced thermoplastic composites were investigated in this study. Materials included carbon fiber-reinforced polyphenylene sulfide (CF/PPS), glass fiber-reinforced polyphenylene sulfide (GF/PPS), glass fiber-reinforced polypropylene (GF/PP), and glass fiber-reinforced polyethylene terephthalate (GF/PET). Fiber orientation was noted to affect the response of the materials to UV and moisture environments. For CF/PPS, UV exposure led to enhanced unidirectional tensile and flexure properties, and quasi-isotropic compression strength, but reduced in-plane shear properties of cross-ply laminates and the short-beam shear strength of unidirectional laminates. Exposure to moisture had minimal effect on CF/PPS laminates. UV light caused a slight decrease in tensile strength and strain of unidirectional samples of GF/PPS and a slight increase in these properties with various degrees in quasi-isotropic samples. Exposure to moisture was noted to cause a reduction in most of the mechanical properties with various degrees in unidirectional and quasi-isotropic GF/PPS laminates. For GF/PP, exposure to UV and moisture decreased the tensile and compressive strengths of unidirectional and quasi-isotropic laminates. However, a notable increase in flexure strength was observed in both laminates after UV exposure. The GF/PET quasi-isotropic laminates showed reduced tension, compression, and flexure strengths but increased impact resistance and short-beam strength under UV exposure, while moisture decreased in-plane shear properties of cross-ply laminates and increased the glass transition temperature of unidirectional laminates. Vertical burn and surface flammability and smoke generation tests showed high flame resistance of CF/PPS and GF/PPS composites, and less so for GF/PP and GF/PET composites. The findings highlight the various responses of the materials to extreme environments.