Extraction and characterization of a novel tropical fibre Megaphrynium macrostachyum as a biosourced reinforcement for gypsum-based biocomposites

Abstract

Identifying the potential of new bast fibres is a solution for diversifying biobased reinforcements and replacing environmentally harmful synthetic fibres. In this study, fibres were extracted from Megaphrynium macrostachyum stems by biological and chemical retting. The chemical fibres were bleached with a 2.5wt% sodium hypochlorite (NaClO) solution. The biological, chemical and bleached fibres were analysed from a chemical, morphological, physical, mechanical and thermal point of view. The possibility of using these fibres as reinforcement in gypsum-based biocomposites for construction was analysed by three-point bending tests. Chemical analysis revealed a cellulose content of more than 56 wt% within the usual range (50-85 wt%) for reinforcing fibres. SEM images showed that bleaching cleans the surface of the fibres. Physical analysis by gravimetric analysis showed that the bleached fibre had the lowest density (1.01 g.cm−3), fineness (5.2tex) and water absorption (64wt%). In addition, the highest thermal stability (237°C) was obtained for the chemical fibre. Young’s modulus and tensile strength, evaluated according to ASTM D3822-07, were dispersed and depended on the fibre diameter, and the highest values were obtained for the chemical fibre (6.4 GPa and 251 MPa). In contrast, gypsum composites with a volume fraction of 1.5% bleached chemical fibre had the highest stiffness (258 MPa) and flexural strength (5 MPa). The results obtained for each fibre type are relatively close to those of other fibres in the literature, indicating that all three fibre types studied can be used as alternative raw materials for the manufacture of gypsum-based biocomposites.