Manufacturing technology and dynamic mechanical investigation of moisture-resistant Luffa cylindrica-reinforced epoxy composites

Abstract

Natural fiber (NF)-reinforced thermosetting composites exhibit excellent properties but, due to the usually hygroscopic nature of the fibers, these composites may suffer from the effects of moisture absorption. Luffa cylindrica is a NF, potentially useful in the manufacture of composite materials, but it is highly hygroscopic. A technology is developed for the fabrication of moisture-resistant L. cylindrica-reinforced epoxy composites and the various parameters that affect the process are investigated using long-term moisture absorption experiments and dynamic mechanical analysis of dry and moist specimens. The technology concludes to a L. cylindrica-reinforced bilayer matrix made of a first linseed oil-modified precured epoxy and a final unmodified epoxy layer. This composite offers a reduced water absorbance by 33% and an almost identical Tg compared to the non-modified epoxy reinforced with L. cylindrica. The same technology is used to manufacture water-resistant L. cylindrica-reinforced composites from both, environmentally friendly, matrix and reinforcement. © 2021 Wiley Periodicals LLC.