Improving carbon fibre reinforced polyphenylene sulfide using amine and phenolic interphase modifications

In this study, a straightforward in-situ surface modification procedure was used to enhance the interfacial adhesion of carbon fibre (CF)-reinforced polyphenylene sulfide (PPS). To do this, 4-nitroaniline and 4-aminophenol were grafted to the surface of carbon fibres. The goal was to capitalise on the hydrogen bonding capability of the grafted molecules with the exposed sulphur groups present in the polymer backbone of PPS. This modification has resulted in a notable enhancement in both the tensile and flexural strength of the PPS/CF composite, with an increase of 12.3% and 19.3%, respectively. Moreover, tensile, and flexural modulus has been increased by 15% and 16%, respectively. Scanning electron microscopy (SEM) examinations confirm that the treated CF contributes to the facilitation of a more homogeneous stress distribution throughout the matrix. This serves to alleviate stress concentrations that may arise at certain spots, reducing the probability of premature failure or crack formation. Counterintuitively, the amino grafted fibres outperformed the phenolic enriched fibres, despite the amine having a lower potential for hydrogen bonding. We propose that the sulphur atom within the PPS polymer presents an opportunity for hydrogen bonding but also a currently underutilised interaction, sigma*-bonding, that could be capitalised on to enhance thermoplastic composite performance. Furthermore, the achievement of effectively preparing a modified CF surface offers valuable insights into the development of highperformance thermoplastic composites using easily accessible materials via a straightforward method.