Mechanical properties of semi-crystalline polymers and composites with a semi-crystalline thermoplastic matrix are highly dependent on the crystallinity and crystalline morphology. The cooling rate from the melt has the greatest effect on this along with other processing conditions. The objective of this study is to evaluate the effects of the cooling rate on the mode I and II fracture toughnesses of the composites with the semi-crystalline thermoplastic matrix. Carbon fiber/polyphenylene sulfide (CF/PPS) composites were fabricated using varying cooling rates. These rates ranged from 1 to 300ºC/min. The degree of crystallinity in the CF/PPS composites was determined using differential scanning calorimetry (DSC). Double cantilever beam (DCB) and end-notched flexure (ENF) tests were performed on the specimens to evaluate the fracture toughnesses of the CF/PPS composites with different cooling rates. Furthermore, the effect of the cooling rate on the mode I and II fracture morphologies of the CF/PPS composites is discussed.
