Long coir and glass fiber reinforced polypropylene hybrid composites prepared via wet-laid technique

Natural fiber composites offer an advantage in terms of weight saving for many automotive applications; however, many natural fiber composites lack properties to justify substitution for synthetic composites. Hybridizing the natural fiber composites by adding a fraction of synthetic fibers is an innovative approach to provide a balance between composite's performance and weight savings. In this study, coir fiber (40 wt %)-reinforced polypropylene (PP) composites were hybridized by substituting a fraction of coir fiber with glass fiber (0-30 wt%). The composites were prepared using a novel wet-laid technique followed by compression molding, where the fiber length is preserved. The composites prepared by hybridizing PP/coir fibers with glass fibers were light in weight (6-20% lighter compared to 40 wt% glass fiber reinforced PP) with significantly enhanced tensile (strength - 49-182%, modulus - 54-130%), flexural (strength - 41-104%, modulus - 64-193%), and impact properties (157 - 474%) compared to 40 wt% coir fiber reinforced PP composites. Furthermore, the addition of glass fiber (10-30 wt%) to coir fiber reduced the water-absorbing tendency (by 18-74%) of PP/coir fiber composites. All in all, this work has potential applications in automotive, mass transit, and truck applications where natural fiber composites are being investigated as alternatives to metal and/or fully synthetic composites.