Effect of fiber treatments on mechanical properties of Grewia serrulata bast fiber reinforced polyester composites

Natural fiber reinforced polymer composites were prepared using unsaturated polyester resin reinforced with bast fibers extracted from Grewia Serrulata trees. The extracted fibers were subjected to sodium hydroxide pretreatment followed by exclusive chemical treatments such as acetylation, permanganate treatment and Silane coupling treatment to modify the fiber surface. Hand lay-up technique was used for the fabrication of uni-directionally oriented untreated and treated fiber reinforced laminates. Mechanical characterization was carried out as per the ASTM- 3039 and ASTM D 790 standards for the tensile and flexural properties respectively. It was found that the tensile modulus of Silane treated Grewia Serrulata fiber reinforced composites was 27% higher and tensile strength of acetylated fiber reinforced composites was 53% higher than untreated fiber reinforced composites. The flexural modulus and strength of treated fiberreinforced composites were considerably higher than the untreated fiber reinforced composites. The fractographs of the samples revealed the improvement in bonding between the chemically treated fibers and the matrix.