Physical, mechanical and thermal properties of Spanish broom (Spartium junceum L.) fibre reinforced unidirectional polyester composites

This research analyses Spanish broom fibres (Spartium junceum L.) as possible reinforcement in polymer composites. It includes fibre extraction, characterisation, and composite construction. We extracted the Spanish broom fibres by water retting for 30 days, followed by hand washing and air drying. The fibres were spun into skeins using circular spinning. The fibres exhibited a density of 1.27 ± 0.03 g/cm ³ and an average diameter of 170 ± 1.80 μm. The SEM investigation revealed a rough, uneven surface with microfibrils and spaces, that are typical of lignocellulosic fibres. Cellulose, hemicellulose, and lignin were detected using FTIR analysis. TGA revealed three weight-reduction phases, with the most significant cellulose degradation temperature around 319°C. XRD analysis revealed a 48.09% crystallinity index and 15.7 nm crystallite size. Single fibre tensile testing showed an elastic modulus of 20.51 ± 5.30 GPa, a fracture stress of 486.17 ± 129.16 MPa, and a fracture strain of 1.57 ± 0.43%. Spanish broom yarn and polyester resin were used to create unidirectional composites. Results indicate that both unreinforced polyester and SJL fibre-reinforced composites have enhanced mechanical characteristics, with maximum stress of 29.79 ± 0.79 MPa and Young’s modulus of 3.10 ± 0.25 GPa. This work highlights the significance of employing Spanish broom fibres as a green reinforcing material for polymer composites and suggests future research options.