Improving the thermo-oxidative stability of low-density polyethylene composites reinforced with Luffa cylindrica fibers

Natural fibres are promising reinforcements for polymer composites due to their affordability, eco-friendliness, and favorable mechanical properties. This study investigates the enhancement of thermo-oxidative stability in low-density polyethylene (LDPE) composites by incorporating 10 wt% Luffa cylindrica fibres, both untreated and chemically modified via alkaline and acetylation treatments. Fourier-transform infrared spectroscopy (FTIR) revealed that alkali treatment increased the lateral order index (LOI) by 188.3 %, cellulose ratio (CR) by 60 %, and the total crystallinity index (TCI) by 9.2 %, indicating improved structural order. Thermogravimetric analysis (TGA) showed higher initial degradation temperatures for ALF (241 °C) and CLF (262 °C) composites compared to untreated fibres (201 °C). After 120 h thermo-oxidative aging at 100 °C, weight loss was lowest for LDPE/ALF (0.65 ± 0.14 %) and highest for LDPE/CLF (0.79 ± 0.2 %). Mechanical tests demonstrated that CLF composites exhibited the highest tensile strength (8.98 ± 0.58 MPa) and elongation at break (13.6 ± 2.3 %). These results confirm that fibre treatments enhance interfacial adhesion, crystallinity, and thermal resistance, making treated luffa fibre/LDPE composites suitable for packaging, automotive, and construction applications requiring improved durability. • Chemical treatments improve luffa fiber-LDPE composite thermal stability. • Alkali and acetylation enhance fibre-matrix adhesion and mechanical properties. • Acetylated fibres yield composites with superior thermo-oxidative resistance. • Treated fibres increase crystallinity, boosting composite durability and performance.