Thermal Analysis on Carbon Fiber Polyphenylene Sulfide Composite Under Thermoforming Process

The aerospace sector is transitioning from thermoset to thermoplastic composites to reduce weight, improve fuel efficiency, and accelerate manufacturing output. Carbon Fiber Reinforced Polyphenylene Sulfide (CF/PPS) composites offer advantageous properties, including improved weldability, enhanced storage stability, and compliance with firesmoke toxicity (FST) standards. This study systematically evaluates the thermal behavior of 6-ply and 8-ply CF/ PPS laminates thermoformed at 150, 160, 170, 180, and 195°C. Differential Scanning Calorimetry (DSC) analyses indicated a positive correlation between tooling temperature and both the crystallization temperature (Tcc) and degree of crystallinity, reflecting enhanced polymer chain mobility and molecular orientation during thermoforming. The 8-ply laminates exhibited earlier crystallization onset and higher crystallinity (~21.18%) due to reduced cooling rates and improved thermal retention, compared to the 6-ply laminates, which showed delayed crystallization kinetics. Thermogravimetric Analysis (TGA) results demonstrated significant improvement in thermal stability post-thermoforming, with char residue increasing from approximately 44-47% in unpressed states to 70-75% in pressed specimens, accompanied by elevated degradation onset and offset temperatures. These enhancements underscore the critical role of optimized tooling temperatures and ply thickness in modulating crystallization dynamics and thermal degradation resistance. The findings substantiate the suitability of CF/PPS composites for aerospace applications requiring stringent thermal durability and structural integrity, including interior panels and load-bearing components subjected to elevated in service temperatures.