Exploring the self-nucleation effect: Transforming crystalline morphology for improved mechanical performance of carbon fiber reinforced polyphenylene sulfide composites

Advanced thermoplastic composites have garnered significant attention due to the advantages such as secondary thermoforming. In the case of thermoplastic composites based on semicrystalline polymers, the self-nucleation (SN) effect induced by repeated thermal cycling can greatly influence the crystallization behavior and mechanical properties of both the matrix and the composites. This study investigated the SN effect of carbon fiber reinforced polyphenylene sulfide (CF/PPS) composites and its impact on non-isothermal crystallization behavior by differential scanning calorimetry, polar optical microscopes and atomic force microscopes. The results revealed that a lower secondary melting temperature led to a higher crystallization temperature. Furthermore, the SN effect significantly improved the fiber/matrix interfacial interaction and mechanical properties of CF/PPS composites. This improvement was evident in the enhanced compression properties, interlaminar shear properties, and in-plane shear properties at different test temperatures. The study also proposed mechanisms for the improved fiber/matrix interfacial interaction and matrix mechanical properties through the SN effect. This work not only enhances our understanding of the changes in mechanical properties of CF/PPS composites due to matrix crystalline morphology changes during secondary thermoforming but also provides insights into improving the manufacturing efficiency and mechanical properties by selecting a low melting temperature to achieve a high crystallization temperature in secondary thermoforming.