Engineering the interfacial adhesion in basalt/epoxy composites by plasma polymerization

In an attempt to improve mechanical properties of basalt fibre/epoxy composites, the present work provides a comparison between the effects of a commercial coupling agent, a thermal de-sizing treatment and a plasma polymerization process on the fibre/matrix interfacial strength. The different basalt fibres were characterized in terms of surface morphology, by FE-SEM observations, and chemical composition, performing FT-IR analysis. The interfacial adhesion has been investigated by single fibre fragmentation test on single filament composite samples. The plasma polymerization process was able to produce a homogeneous tetravinylsilane (pp-TVS) coating on the surface of basalt fibres, which resulted in a significant increase in the fibre/matrix adhesion. The surface roughness of the untreated and treated basalt fibres has been measured by AFM and a relationship between the surface roughness and the fibre/matrix adhesion quality was found. High-resolution microtomography (µ-CT) has been used to support the analysis of the damage modes during fragmentation tests.