Covalent functionalization of carbon fiber with poly(acrylamide) by reversible addition-fragmentation chain transfer polymerization for improving carbon fiber/epoxy interface

A novel method was developed for grafting poly(acrylamide) (PAAM) on to the carbon fiber (CF) surface via reversible addition–fragmentation chain transfer (RAFT) polymerization to improve the interaction between carbon fibers and epoxy matrix in the composites system. The carbon fibers were first treated with nitric acid and γ-methacryloxypropyltrimethoxy silane (KH570). Then, the PAAM was grafting onto the carbon fiber surface via RAFT polymerization. The resulted carbon fibers functionalized with PAAM (CF-PAAM) were characterized by FTIR, XPS, and TGA, and the results revealed that CF-PAAM were synthesized successfully. The introduction of PAAM chains could make the fiber surface rougher and introduce a large numbers of –NH2 groups, which can improve the interfacial adhesion in the composites. The microbond test results showed that the interfacial shear strength (IFSS) of the composites reinforced by CF-PAAM has been enhanced about 107%. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers