Improving mechanical properties of high-temperature resistant carbon fiber/phthalonitrile composites via surface modification: a comparative study on modification methods

ABSTRACTThe interfacial bonding is of essential importance for the mechanical properties of high-temperature resistant carbon fiber/phthalonitrile composite materials. To promote the interfacial adhesion of carbon fiber/phthalonitrile composites, three surface modification methods, namely HP302 sizing, diazotization modification, and oxidation-diazotization modification, were applied and compared. The results showed that the de-sizing treatment barely affected the mechanical properties of the composites. Both re-sizing with HP302 agent and diazotization modification improved the mechanical properties, while the mechanical properties were drastically decreased via the oxidation-diazotization modification. Among these surface modification methods, the diazotization treatment derived the best mechanical properties of carbon fiber/phthalonitrile composites both at room and high temperature. Specifically, the flexural strengths were 345 MPa (RT), 525 MPa (300°C), and 442 MPa (400°C), which were 47%, 302%, and 281% higher than those of the pristine composites. The interlaminar shear strengths were 33 MPa (RT), 26 MPa (300°C), and 27 MPa (400°C), which were all over twofold than those of the original counterparts.KEYWORDS: Carbon fiberphthalonitrile resincomposite materialssurface modificationmechanical properties Disclosure statementNo potential conflict of interest was reported by the author(s).Supplemental dataSupplemental data for this article can be accessed online at https://doi.org/10.1080/09276440.2023.2262253Additional informationFundingThis work was supported by the Key Research and Development Program of Hunan Province, China (Great numbers 2018GK2062). Jun Tang would like to acknowledge the financial support from National Natural Science Foundation of China with grant No. 52003295.