the thermomechanical stability of a number of organosilane surface treatments for glass fibers were evaluated for use in a fiber reinforced epoxy resin. all of the silane coatings were found to improve the tensile strength of e-glass filaments, particularly at large gauge lengths. a phenylamino silane and an amino silane were particularly effective in this regard. the fiber/matrix interface was evaluated as a function of temperature and after exposure to boiling water using a single-fiber composite test. all silane coatings transmitted a higher interfacial shear stress than obtained in composites with no coatings, and in all cases the shear stress transmission was considerably higher than would be expected from the yield properties of the resin. measurements of the glass transition temperature of the epoxy resin, as well as fourier-transform infra-red analysis, indicated modification of resin properties in a zone around the glass fibers. unidirectional e-glass fiber reinforced laminae were fabricated and the measured values of longitudinal strength were compared favorably to theoretical predictions. (edited author abstract) 43 refs