Compressive behavior of notched and unnotched carbon woven-ply PPS thermoplastic laminates at different temperatures

The temperature dependence of compressive behavior for notched and unnotched specimens is essential for structural design and applications of woven carbon fabric/polyphenylene sulfide (CF/PPS) laminates. Thermal properties of CF/PPS composite were studied by DMA and DSC analysis. Compressive experiments of notched and unnotched specimens at different temperatures (25 °C, 95 °C, and 125 °C) were conducted. Compressive tests for notched specimens at 200 °C were also taken into account. Failure modes were examined by scanning electron microscope (SEM) and stereomicroscope. It was found for unnotched specimens that with the increase of temperature the compressive strength exhibited an obvious decline due to the softening of matrix, while the modulus decreased initially and then increased because of the cold crystallization. For the notched specimens, the strength decreased slightly compared with that of unnotched specimens, which could be attributed to the stress concertation accommodation mechanism. There was a transition failure mode from brooming to kink band for the unnotched specimens with the increase of temperature, which were closely associated with the matrix state and weave architecture characteristics. But the notched specimens appeared more complex failure modes, especially at 95 °C. Two different failure modes were detected, which could be recognized as a critical transition state.