Comparative Study of Chemical Modification of Natural Fibers for Improved Mechanical Properties in Composite Materials

Abstract

Natural fibers are increasingly investigated as low-density and renewable reinforcements for polymer composites, but their hydrophilic surfaces, waxes, lignin and hemicellulose reduce compatibility with hydrophobic matrices and restrict mechanical performance. This methodology paper proposes a controlled comparative study of chemical surface modification routes for improving the tensile, flexural and impact properties of natural-fiber composites. Jute fiber and epoxy resin are selected as a representative industrial composite system. Five fiber conditions are compared: untreated fiber, sodium-hydroxide (alkali) treatment, silane treatment, sodium-bicarbonate treatment and sequential alkali-silane treatment. The experimental design maintains constant fiber loading, fiber length, resin system, curing schedule and fabrication method so that differences can be attributed primarily to surface treatment. Modified fibers are characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, water absorption and single-fiber tensile testing, while composites are evaluated for tensile, flexural, impact and interfacial performance. Literature through 2021 indicates that alkali treatment removes non-cellulosic constituents and increases roughness, whereas silanes can form chemical bridges between cellulose and polymer matrices; combined treatment can therefore provide stronger interfacial load transfer. An illustrative result set is included only to demonstrate the proposed analysis and ranking procedure. The methodology is intended to support material selection for automotive panels, construction components, furniture, packaging and other lightweight industrial products.