Manufacturing of composite materials with high environmental efficiency using epoxy resin of renewable origin and permeable light cores for vacuum-assisted infusion molding

Abstract

This work focuses on the manufacturing and characterization of novel and lightweight hybrid sandwich-type structures, using different stacking sequences of flax and basalt fabrics as reinforcement fibers, both of them previously silanized. To reduce the overall weight and facilitate the manufacturing process, a polyester non-woven core, was used which, besides reducing the weight of the composite it also acts as a media to spread the resin. These composites were manufactured with a partially bio-based epoxy resin with a reactive diluent derived from epoxidized vegetable oils that contributes to a 31 % of biobased content. The hybrid composites were obtained by vacuum-assisted resin infusion moulding (VARIM), where the core was used as a media to spread the resin. The mechanical properties were evaluated in flexural and impact conditions. The interactions in the fiber-matrix interface were studied through field emission scanning electron microscopy (FESEM). The obtained data revealed that the silane (coupling agent) treatment works better on basalt fibers than on flax fibers, resulting in superior flexural properties on structures where these fibers are present. It is noteworthy to mention that the stacking sequence of plies directly influences the flexural properties, but it does not significantly affect the energy absorbed when these composites work on impact conditions.