Mechanical properties investigation of green composite from ramie (Boehmeria nivea (L.) Gaud) and epoxy

Abstract

In the last decade, the requirement of friendly environment materials has increased significantly. Green composite material, such as natural fiber reinforced epoxy composite, has been developed to provide an environmentally friendly product. Ramie (Boehmeria nivea (L.) Gaud) fiber and bio-epoxy are potential materials to produce an excellent environmentally friendly composite. The physical and mechanical properties of the composite were evaluated. Each composite material has three different layers of ramie fiber orientation, i.e., 0, 45, and 90°. Ramie fiber contents were varied by 5, 7.5, and 10% w/w of composite weight. The content variations of epoxy matrix hardener were 25 and 50% w/w of matrix weight. The replication of each sample was three times. The making of the ramie fiber-epoxy lamina composite was started with mixing the epoxy with a hardener, followed by pouring the matrix on the mold and coating the layers of fibers layer by layer until a composite was obtained according to the specified layer variations. The sample was poured into mold-press for 24 hours. Then, samples were removed from the mold and put in the oven at 60°C for 24 hours. For conditioning, the samples were placed in an open space at room temperature (27°C) for seven days. The dimension of the samples was 150 mm × 100 mm × 3 mm. For the composite materials, tensile testing and flexural testing standard were ASTM D 638 and ASTM D 790, respectively. The research results showed that the composite with 25 % of hardener (w/w matrix weight) and 5 % of ramie fiber (w/w composite weight) had the lowest thickness swelling (0.17%). However, the highest tensile strength (45.8 MPa) was obtained by the composite with 25 % of hardener (w/w matrix weight) and 10 % of ramie fiber (w/w composite weight). Meanwhile, the flexural strength of the composites with 50 % of hardener, either with 5 or 7.5 % of ramie fiber, was higher than the other composites. Composite materials, which contain 10% of ramie fiber (w/w composite weight) and 25% of hardener (w/w matrix weight), had the best mechanical properties.