Novel co-bonded thermoplastic elastomer-epoxy/glass hybrid composites: The effect of cure temperature on the interphase morphology

High adhesion strength in hybrid composites is a decisive factor for their widespread use in lightweight structures. The bond strength of co-bonded thermoplastic-thermoset composites is largely influenced by the interphase thickness and morphology, which are controlled by the cure and diffusion kinetics. Hence, this study aims to characterize the interphase of a hybrid composite comprised of thermoplastic elastomer (TPE) co-bonded to glass fiber reinforced epoxy (epoxy/glass) by correlating the cure temperature with the interphase thickness and morphology. The interphase thickness is analyzed with light microscopy, while the morphology is studied with scanning electron microscopy (SEM) and atomic force microscopy (AFM) employing the PeakForce quantitative nanomechanical mapping mode (PF-QNM). The relationship between interphase thickness and cure temperature is investigated by assessing the diffusion and cure kinetics with a rheometer. It was observed that phase separation took place at the interphase, while the interphase thickness and morphology depended on cure temperature.