Effects of Kevlar volume fraction and fabric structures on the mechanical properties of 3D orthogonal woven ramie/Kevlar reinforced poly (lactic acid) composites

The proposed 3D orthogonal woven ramie/Kevlar reinforced poly (lactic acid) composite in this paper is a new type composite in which the 3D orthogonal structure has great advantages of high impact and delamination resistance due to the Z yarns and the hybridization of natural and manmade fibers provides not only partial environment friendly benefit but also efficient compensation for the relatively low mechanical properties from pure natural fibers. Eight types of the aforementioned composites were designed and fabricated. The results showed that as the volume fraction of Kevlar was increased, the tensile properties showed increasing trends, while the flexural properties were predominantly dependent on the fabric structures, especially, the weft yarns properties in the first and second layers from the upper and bottom surfaces. Furthermore, the impact strength was enhanced as the volume fraction of Kevlar increased to 5.5% and leveled off when Kevlar yarns continuously increased.