Mechanical, thermal and ballistic performance of epoxy composites reinforced with Cannabis sativa hemp fabric

Among the natural fibers, the hemp fiber extracted from the stem of Cannabis sativa is, after sisal, the second most applied as reinforcement of polymer composites and increasingly used from automotive to civil construction industries. Polypropylene (PP) is the most common hemp fiber-reinforced matrix. Despite numerous papers on the application of natural fibers reinforcing polymer composites for ballistic protection, only one was so far dedicated to hemp fibers/PP with this purpose. In the present work, the main objective is for the first time to investigate the ballistic performance of the epoxy matrix reinforced with up to 30 vol% of hemp fabric. Epoxy is recently emerging as another strong alternative for the hemp fiber/fabric matrix. Due to the great variability in properties, a preliminary investigation was conducted on the basic mechanical and thermal behavior of the composites. The 30 vol% reinforcement with hemp fabric increased by 7.5 times the Izod impact energy as well as by more than 60% the tensile strength and 80% of the elastic modulus as compared to the neat epoxy. For all composites, a decrease of 20% in thermal temperatures (Tonset and Tmax) occurred in comparison to neat epoxy. The absorbed ballistic energy from the impact of 0.22 ammunition was significantly higher (95–108.5 J) than that previously reported of 36 J for hemp fabric/PP composite and others natural fiber/epoxy composites.