Dyeability and mechanical properties of banana fiber reinforced polypropylene composite

Abstract Banana fibers being highly strong and biodegradable, have always been an interesting aspect of polymer science. The research examines the pretreatment process to enhance the dyeability of banana fibers with synthetic dyes, followed by the preparation of polypropylene (PP) composites with dyed fibers to explore their mechanical properties. Raw banana fibers were extracted from the pseudo stems of banana plants for pretreating with sodium hydroxide and hydrogen peroxide and further dyed in the exhaust method using direct, basic, reactive, and vat dyes. Despite a decrease in fiber strength, the scoured‐bleached fibers appeared whiter and lustrous compared to untreated fibers. Direct dye exhibited a higher color strength (K/S) value of 20.7 and better wash fastness on average of 4‐3 rating compared to basic dye. Later polypropylene sheets were prepared using a Hot Plate Molding Machine, and composite specimens were fabricated by sandwiching the fibers between PP sheets and hot pressing. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed minor bond formations between the dyed fibers and polypropylene matrix in composites showing significant bonding at NH, CH, and OH regions. The composites containing dyed fibers showed slight improvements in tensile strength and modulus which is at best 2% than that of untreated fiber. Highlights Direct and basic dyes were determined as the most suitable synthetic dyes. FTIR analysis revealed minimal bond formation between the fiber and PP matrix. Composites having dyed banana fiber showed little better mechanical features.