Mechanical properties of carbon fiber/PPS laminates processed by hot compression molding under different consolidation cycles

High-performance thermoplastic composites based on semipregs of poly(phenylene sulfide) (PPS) reinforced with carbon fiber (CF) have been widely used in the aerospace industry due to their excellent mechanical properties and thermal stability. In this work, CF/PPS laminates were processed by hot compression molding. The processing parameters (pressure and temperature of processing) were investigated as well as the effect of the number of semipreg layers. The neat PPS matrix and CF/PPS semipreg were evaluated by rheological and thermal properties, respectively, to verify the best processing temperature for the CF/PPS composite laminates. The CF/PPS laminates obtained were inspected by ultrasound and differential scanning calorimetry analyses, and then the standardized specimens were prepared. The mechanical properties were evaluated by tensile test and interlaminar shear strength (ILSS) tests. Morphological characteristics of fracture surfaces also were analyzed by scanning electron microscopy. The ultrasound inspections showed differences among the processed laminates with the presence of defects mainly around the edges of samples. Based on ultrasound maps, the worst regions of laminates were discharged and not used to cut the specimens utilized in the mechanical characterization. Thermal, mechanical, and morphological analyses of the six laminates processed with different consolidation cycles did not show significant differences, showing good CF-PPS matrix interface and similar results of crystallization (similar to 23%), tensile strength (776-858 MPa), and ILSS (59-68 MPa).