Influence of sizing formulations on glass/epoxy interphase properties

A series of fiber sizing formulations have been chosen to compare the effect of silane coupling agent and film former on the properties of glass fiber/epoxy interphase. The microdroplet debond test was chosen to measure the strength and energy absorption of the interphases. Results indicate that chemical reactivity and wettability of polymeric film former influence the strength and energy absorption for glass fiber/epoxy interphases. Comparison of amino silane sizings with different film formers show that the azamide-based film former provided a 47% increase in interfacial shear strength over other sizings studied. The results demonstrate that the relative reactivity and wettability of film former can enhance both chemical bond formation and fiber surface roughness. Changes in fiber surface morphology due to application of sizing were observed by Atomic Force Microscopy (AFM). Analysis of failed surfaces indicate that both silane and film former components affect the mode of failure at the interface.