Effect of chemical modification on the mechanical and electrical properties of banana fiber polyester composites

Banana fiber obtained from the sheath of the banana plant, Musa sapientum, has been used in the preparation of composites with polyester matrix. The effect of fiber loading on the dielectric constant, volume resistivity, and dielectric loss factor of the composites were determined with special reference to the effect of frequency. The fibers were modified chemically in order to have better compatibility with the matrix. The surfaces of the modified fibers were characterized using techniques like solvatochromism, zeta potential measurements, X-ray Photo electron spectroscopy (XPS), and Scanning Electron Microscopy (SEM). The effect of fiber surface modification on the mechanical as well as electrical properties of the composites was evaluated. Fiber surface modification was found to influence both mechanical as well as electrical properties of the composite. The mechanical properties were found to be improved based on the improved interaction between the fiber and the matrix which in turn was found to be dependent on the surface polarity of the chemically modified fibers. The value of the dielectric constant was found to be influenced when the fiber loading reaches an optimum value. The dielectric constant values of the treated fiber composites were found to be lower than the untreated composites. The electrical conductivity of the composites was found to be dependent on the chemical modification as well as the fiber loading employed. Maximum conductivity was observed for composites with an optimum fiber loading of 40% as well as for those treated with methacryloxy silane. In addition to the other techniques, conductivity measurements can be used as an effective tool to evaluate interfacial adhesion in composites.