Optimization of Carbon Fiber Surfaces for Reinforcement in Advanced Polymer Composites

摘要

This paper summarizes recent efforts within our research group to optimize theinterfacial adhesion of carbon fiber reinforced polymer composites (CFRPs). Thiseffort has been approached by several avenues including surface modification ofcarbon fibers, and the use of molecular dynamics to determine key interfacialinteractions determining optimal adhesion. Typically, surface manipulation of carbonfibers is carried out using reductive electrochemical techniques, employingirreversible single electron reduction of aryldiazonium salts. Though recent effortshave shown oxidative surface grafting of carbon fibers is possible using the Kolbedecarboxylation reaction. Both approaches create a fiber which possesses a covalentlybound surface modification, able to present a myriad of chemistries to the supportingresin. Determination of interfacial shear strength (IFSS), using single filamentfragmentation in epoxy resin, has shown IFSS gains of over 150%, relative to pristineunsized fiber. Interrogation of the fiber-matrix interface using molecular dynamicssimulation has shown that a large degree of the IFSS gains are derived from themolecular ‘drag’ effect of the surface bound molecules through the polymer phase.Further benefits of this approach can also be realized by combining the surfacemanipulation techniques with novel sizing agents, able to plasticize the localized resinaround the carbon fiber, giving a gradient interphase. When used in concert, thesynergistic effects of surface modification and interphase manipulation has realizedIFSS gains >250% relative to control fibers.