Ramie fibers and plant
Ramie (Boehmeria nivea) fiber is one of the superior strength lignocellulosic fibers, but the least investigated particularly as a reinforcement to obtain tougher polymeric composites. This paper, just published in Materials Research and entitled Reinforcement of Polyester with Renewable Ramie Fibers, presents mechanical properties for polyester reinforced with aligned ramie fibers in volume up to 30 %. In this collaborative project with the Institute of Military Engineering in Rio de Janeiro (Brazil), it was found that adding 30 vol.% of ramie fibers increases the flexural strength of polyester about three times (212 MPa vs. 65 MPa) and tensile strength nearly two times (85 MPa vs. 47 MPa). Polyester-ramie fiber composites also displayed a significant improvement in toughness. The impact energy value (~1 kJ/m) as measured by Charpy test and Izod impact energy value (~0.55 kJ/m) increased two orders of magnitude for 30 vol% ramie fiber composite as compared to neat polyester (~ 0.015 kJ/m).
Fractographic studies revealed good wetting of the fibers by polyester. Limited fiber-matrix adhesion was reflected in preferential longitudinal propagation of cracks along the fiber/polyester interfaces, indicating also that most of the fracture area is associated with the fiber surface.
