Enhancing the Interlaminar Shear Performance of Carbon Fiber‐Reinforced Thermoplastic Composites by Introducing Sulfonated Polyphenylene Sulfide Onto Activated Carbon Fibers

ABSTRACT In this study, sulfonated polyphenylene sulfide (SPPS) with varying sulfonation degrees was synthesized to enhance the interfacial properties of carbon fiber reinforced polyphenylene sulfide (CF/PPS) composites. The structure and chemical functionality of SPPS were thoroughly characterized. Thermogravimetric (TG) analysis and differential scanning calorimetry (DSC) tests demonstrated that the thermal stability of SPPS meets the requirements for its application as a sizing agent. SPPS was used to size CFs surface treated with Meldrum's acid, and the surface elemental composition of SPPS‐sized CF (SPPS‐CF) at various concentrations was analyzed using X‐ray photoelectron spectroscopy (XPS). The results revealed that, compared to the untreated carbon fiber/PPS (U‐CF/PPS) composites, the interlaminar shear strength (ILSS) of SPPS‐CF/PPS composites increased by 158%. This marked improvement can be ascribed to two primary factors: (i) the increase in surface energy of the CFs due to the incorporation of activated carbon fiber (A‐CF) and the polar groups in SPPS, which enhanced the wettability between the fiber and the resin—as evidenced by a rise in total surface energy from 28.5 mJ/m ² for D‐CF to 39.3 mJ/m ² for SPPS‐CF (0.4%) (an increase of 42%), accompanied by a decrease in the dynamic contact angle with deionized water from 79.3° to 61.8°; (ii) the establishment of excellent compatibility between the SPPS sizing agent and the PPS matrix due to their similar solubility.