Manipulating Interfacial Strength of Polyphosphazene Functionalized Carbon Fiber Composites

To gain a better understand the correlation between the amount of polar functional groups and interfacial properties, we propose to functionalize carbon fiber (CF) with amine‐capped cross‐linked polyphosphazene (ACP) and tailor the polycondensation time, aiming to control the amount of amine groups on CF surface. The chemical composition and surface morphology of modified CF were systematically investigated. The results show that the ACP was uniformly distributed on CF surfaces. X‐ray photoelectron spectroscopy results confirmed that the quantity of amine groups is proportional to that of grafted ACP as the reaction time prolong, and it reaches the plateau when the reaction time exceed 35 h. The microbond testing results reveal a positive correlation of the amount of amine groups and interfacial shear strength, and the ACP‐grafted CF with 35 h reinforced composites possess best IFSS (92.1 MPa), with an increase of about 33.5% compared with that of oxidized CF‐reinforced composites. POLYM. COMPOS., 40:E1831–E1839, 2019. © 2019 Society of Plastics Engineers