Physico-mechanical evaluation of benzoyl peroxide-treated water hyacinth reinforced polyvinyl alcohol composites and DFT studies of the reaction of the monomer of cellulose

The growing interest in natural fiber-reinforced polymer composites is driven by their sustainability and enhanced mechanical properties. In Bangladesh, the unchecked proliferation of water hyacinth has become a significant environmental issue, altering the pH and salinity of aquatic ecosystems. This study explores the potential of untreated and chemically treated water hyacinth fibers as reinforcement in polyvinyl alcohol (PVA) composites. The untreated water hyacinth (UWH) was subjected to alkali treatment to produce mercerized water hyacinth (MWH), then oxidation to produce oxidized water hyacinth (OWH). The structural modifications of UWH, MWH, and OWH were confirmed through ATR-FTIR spectroscopy. Composites were fabricated by embedding UWH and OWH fibers into PVA at varying concentrations (0.50, 1.00, 2.5, and 5.0 wt%) via compression molding. Composites with 1 % OWH exhibited the best performance, showing a 127 % increase in tensile strength, 162 % increase in elongation, and 28 % reduction in water absorption compared to UWH-PVA and pure PVA. The improved performance of OWH-PVA composites is attributed to enhanced fiber–matrix adhesion. Thermogravimetric analysis confirmed thermal stability, and Density Functional Theory (DFT) calculations supported the chemical modifications observed experimentally. These results highlight the potential of water hyacinth fibers as a sustainable reinforcement material for PVA-based composites. • Water hyacinth fibers are utilized as a sustainable and eco-friendly reinforcement for polyvinyl alcohol (PVA) composites. • Alkali and oxidation treatments enhanced the oxidized water hyacinth (OWH) fiber–matrix (PVA) adhesion. • OWH–PVA composites showed superior mechanical performance. • The structural changes in cellulose of OWH were validated by DFT and NBO studies.