Static and dynamic properties of single and multi-fiber/epoxy composites modified by sizings

A challenging issue in composite research is to relate microscopic interphase characteristics to macroscopic static and fatigue properties. Here, we systematically analyze fiber surface sizing effects on composites’ mechanical performance using the quasi static single fiber pull-out test and a cyclic loading (micro-fatigue) test, dynamic mechanical thermal analysis (DMA), fatigue and other mechanical tests. Our experiments show that the polymer sizing provides the glass fiber with significantly improved both static and fatigue properties. Together, these results demonstrate a correlation between the fatigue behavior and the interfacial adhesion, with the higher interfacial adhesion performing better in fatigue, where the interface should dominate in determining fatigue life. A cooperativity analysis of DMA data reflects constriction effects on molecular mobility of matrix and is consistent with the results of interfacial adhesion and the tendency of fatigue resistance.