Characterization of a novel cellulosic fiber from Broussonetia papyrifera L. bark for green-epoxy composite: Effect of fiber treatment.

The energy, economic and environmental concerns had attracted the use of alternative eco-friendly cellulosic fibers in epoxy composites. The current work focused on the extraction and characterization of cellulosic fibers from biomass waste of Broussonetia papyrifera L. plant barks, exploring its application suitability for epoxy composite applications. The extracted Broussonetia papyrifera L. fiber (BPF) was subjected to alkali (NaOH) treatments, and then the influences of different alkali solution concentrations on physical, chemical, thermal, mechanical and morphological properties of the BPFs before and after alkali treatments were comprehensively characterized. The experimental results showed that the density of the BPFs was increased by 8.76 %-22.62 %, the moisture content, moisture regain and water contact angle were decreased by 4.71 %-18.66 %, 6.18 %-19.74 %, 7.61 %-60.64 %, respectively, after alkali treatments. SEM images showed that the rough surface and some microfibrils were presented on the surface of the treated BPF. FTIR analysis confirmed that alkali treatment effectively removed the amorphous components from the BPF surface. The crystallinity index (from 66.91 % to 76.16 %) and crystallite size (from 1.21 nm to 2.98 nm) were significantly increased, and the thermal stability temperature (from 296 °C to 323 °C), degradation temperature (from 341.76 °C to 372.20 °C), and Ea (from 77.50 kJ/mol to 92.69 kJ/mol) of the BPFs were also found to be improved. The mechanical property test revealed that the tensile strength was increased from 75.22 MPa to 125.79 MPa and Young's modulus was increased from 4.30 GPa to 7.48 GPa. The above-mentioned test results indicated that the alkali treated BPFs have desirable properties and suggested to be a potential novel resource of reinforcement to strengthen the green-epoxy composites in a sustainable way.