Effect of nanofiller concentration on the density and void content of natural fiber-reinforced epoxy composites

In natural fiber polymer composites (NFPCs), void formation is a typical issue that degrades the composite physical and mechanical properties and limits their uses in aerospace, automobiles, construction, and marine applications. This study uses 50-nm-sized alumina (Al2O3) and magnesia (MgO) nanofillers with epoxy resin to manufacture flax/PLA and jute composites by vacuum bagging technique. The Al2O3 and MgO nanofiller loading in epoxy composites ranged from 0 to 4 wt.% with a 1 wt.% gap. SEM was utilized to examine the morphology and interfacial bonding of the fiber matrix in composites. As the nanofiller loading in the composites grew, the fiber volume fraction decreased with the increase in the density and void content %. MgO filled laminates have shown higher void content than Al2O3 filled laminates due to their low theoretical density, which is inversely proportional to the voids content percentage. Jute-reinforced laminates have shown less fiber volume fraction and higher void content than flax/PLA-reinforced laminates due to the jute fiber's high density. The SEM images of the generated laminates show voids, cracks, fiber breakage, bending, and pull-out moieties.