Increased interfacial adhesion between carbon fiber and poly(vinylidene fluoride) by an aqueous sizing agent

The adhesion behavior of poly(vinylidene fluoride) (PVDF) to carbon fiber (CF) has always been a huge challenge, on account of the inertness nature of PVDF and the lack of reactive functional groups. In this work, a novel maleic anhydride grafted PVDF (MPVDF) aqueous sizing agent was prepared to modify the interface between CF and PVDF matrix. The surface properties of desized, MPVDF‐sized, and PVDF‐sized carbon fibers were characterized by the scanning electron microscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, and dynamic contact angle analysis test. The results demonstrated that the surface roughness increased from 39 to 55 nm, and surface energy increased from 40 to 74 mN m^?1 after MPVDF sizing treatment. The content of activated carbon atoms increased from 31.0% to 48.4%. Subsequently, the interlaminar shear strength was examined, for which was a critical indicator of the interfacial adhesion between CF and matrix. Compared with the desized CF, the value of interlaminar shear strength increased from 14.8 MPa to 25.5 MPa improved by 72% because of the improved H‐bonding formation, surface roughness, and wettability for MPVDF‐sized CF. In addition, the flexural strength and modulus were also improved by 47% and 74%, respectively. Copyright © 2016 John Wiley & Sons, Ltd.