Eco-engineered prosopis juliflora biochar–reinforced recycled polypropylene biocomposites for enhanced mechanical and thermal performance

Escalating environmental concerns associated with plastic waste accumulation and the unchecked spread of invasive biomass species have intensified the pursuit of sustainable, high-performance materials. This study presents the fabrication and characterization of eco-engineered Prosopis juliflora biochar–reinforced recycled polypropylene (PP) biocomposites designed to enhance the mechanical and thermal functionalities of recycled polymers. Activated biochar derived from P. juliflora wood waste was incorporated into PP at 2, 4, and 6 wt.% using twin-screw extrusion followed by injection moulding. Mechanical evaluations revealed that biochar incorporation significantly improved tensile, flexural, and impact properties, with the 4 wt.% formulation exhibiting the optimum performance achieving tensile and flexural strengths of 26.23 MPa and 23.92 MPa, alongside superior elongation and toughness. Thermogravimetric analysis demonstrated delayed onset and peak degradation temperatures, indicating enhanced thermal stability attributed to the carbonaceous structure and barrier effect of the filler. SEM examination of fractured specimens confirmed strong interfacial adhesion and effective stress transfer between biochar and the PP matrix. Beyond performance enhancement, this work validates the sustainable valorisation of invasive P. juliflora biomass into functional biochar, offering an environmentally responsible pathway for upgrading recycled polypropylene. The developed biocomposites show promising potential for applications in automotive components, packaging, and construction materials, contributing to circular-economy practices and next-generation sustainable material innovation.