Improvements in mechanical properties of carbon fiber-reinforced epoxy composites: A microwave-assisted approach in functionalization of carbon fiber via diamines

•A microwave-assisted approach was introduced for functionalization of carbon fibers.•Carbon fibers were functionalized by aliphatic and aromatic diamines.•Compatibility of carbon fiber with epoxy resin was enhanced.•Considerable improvements were observed in mechanical properties of reinforced composites.

A microwave-assisted approach was introduced for functionalization of carbon fibers (CFs) via aliphatic and aromatic diamines in order to enhance the interactions between CF filaments and epoxy resin. CFs was successfully functionalized via one monoamine and three diamine functions. Qualitative (FT-IR) and quantitative (TGA) characterizations have been performed to study the effect of operational parameters, such as retention time and microwave output power, on functionalization degree of CFs. Single fiber tensile testing was employed to investigate possible disruption of CF structure during the functionalization. Moreover, wettability of functionalized CFs was characterized in order to assay the compatibility of functionalized CF with epoxy resin. Mechanical properties of CF-reinforced composites also evaluated for all functionalized CFs. Results revealed that the proposed functionalization procedure is able to highly functionalize the CFs without any discernable structural disruption. Moreover, functionalized CFs demonstrates better compatibility with epoxy resin which led to considerable improvements in mechanical properties of composites (60%). The reinforcing mechanism of different aliphatic and aromatic diamines was also compared in detail.