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Factors That Affect Adhesion at the Fiber-Matrix Interface in Composites



Gale A. Holmes, E Feresenbet, E Pohl, Walter G. McDonough, D T. Raghavan, D Thompson


The development of methods to assess adhesion at the fiber-matrix interface in composite materials has been driven primarily by the recognition that the interface or interphase in many composite materials has a profound affect on the onset of failure in composites. Although several methods have been developed to assess adhesion at the fiber-matrix interface, the single fiber fragmentation test (SFFT) is preferred among researchers because the loading of the fiber is consistent with the fiber loading in full-scale composites. In the SFFT technique, a single fiber is aligned along the axis of a dog bone cavity and embedded in a resin having an extension-to-failure that is typically 3 to 5 times higher than the fiber. The matrix is strained until the resulting fiber fragments are too short for a sufficient load to be transmitted into them to cause additional failure. This point is termed saturation. The lengths of the fragments at this point reflect the adhesive character of the fiber-matrix interface. Research results by Holmes et al. on uncoated E-glass fibers embedded in resin matrices have shown that the adhesive strength of the fiber-matrix interface as assessed by the SFFT can be rate sensitive. Since adhesion at the fiber-matrix interface in glass composites is often optimized by the addition of silane coupling agents to the glass surface, our research has been extended to include E-glass fibers coated under laboratory and industrial conditions. Preliminary results from E-glass fibers coated with the -aminopropyl triethoxysilane coupling agent indicates that the concentration of the precipitating solution has a profound affect on the sensitivity of the fiber-matrix interface to testing rate. The inference of these results to full-scale composite performance will be discussed.
Adhesion Society


adhesion, debonding, glass fiber, interface/interphase, interfacial shear strength, matrix cracks, silane coupling agent, single fiber fragmentation test, stress concentration


Holmes, G. , Feresenbet, E. , Pohl, E. , McDonough, W. , Raghavan, D. and Thompson, D. (2000), Factors That Affect Adhesion at the Fiber-Matrix Interface in Composites, Adhesion Society, [online], (Accessed July 13, 2024)


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Created December 31, 1999, Updated October 12, 2021