Characterization of Chemically and Thermo-chemically Treated Water Reed and Mokolwane Palm Fibers

Water reed (Phragmites spp.) and mokolwane palm (Hyphaene spp.) natural fibers, building materials indigenous to Botswana are potential reinforcement materials in manufacturing composites due to their desirable light weight, mechanical properties, and recyclable nature. Nevertheless, the surface modification mechanism and its effects on the quality characteristics of these fibers have not been explored. This study compares the impact of chemical and thermo-chemical surface treatments on the properties of the fibers. Furthermore, a suitable treatment method and fiber to produce natural fiber-reinforced polymer composites (NFRPCs) were identified. Thermo-chemical treatment is more effective in improving the thermal resistance and mechanical properties of the fibers relative to chemical treatment. Water reed fiber treated by 1.5 wt.% NaOH solution for 15 days followed by thermal treatment at 80°C for 24 hours is best for suitable for building insulation applications considering its quality characteristics (namely: tensile strength (76.41 MPa), CI (59.2%), CS (21.44 nm) and degradation temperature range of 288–598°C). Surface modification mechanism of the fibers by chemical treatment occurred via dissolution of hemicellulose which increased the interfibrillar region while the incorporation of thermal treatment further promoted the rupture of bonds existing between the cellulose and hemicellulose.