Bio-Derived Hard Carbon from Bassia scoparia as a Multifunctional Reinforcement for Chlorinated Polypropylene: Structural, Thermal, and Bioactive Performance.

The development of sustainable multifunctional polymer composites with enhanced thermal, mechanical, surface, and bioactive properties is important for advanced coating and packaging applications because conventional polypropylene (PP)-based materials generally lack intrinsic antioxidant and antibacterial functionality. In this study, nitric acid-treated hard carbon derived from Bassia scoparia biomass (N-BSHC) was utilized as a sustainable multifunctional reinforcement for chlorinated polypropylene (PP-Cl) composite films. Composite films containing 1.0, 1.5, and 2.5 wt% N-BSHC were fabricated by solution casting and characterized using Fourier transform infrared, scanning electron microscope-energy-dispersive X-ray (SEM-EDX), water contact angle (WCA), thermogravimetric analysis, differential scanning calorimetry, mechanical testing, and antioxidant and antibacterial assays. SEM-EDX analysis confirmed homogeneous filler distribution and the presence of oxygen- and nitrogen-containing surface functionalities, which improved matrix compatibility and surface wettability. The WCA decreased from 105° for neat PP-Cl to 94° for the composite containing 2.5 wt% filler. Thermal degradation temperatures increased from 338°C/421°C to 346°C/428°C, while the elastic modulus increased from 48.56 to 73.61 MPa at 1.5 wt% filler loading. Furthermore, the composites exhibited antioxidant activity and strong antibacterial performance against Staphylococcus aureus and Escherichia coli. These findings demonstrate that biomass-derived N-BSHC is an effective sustainable filler for advanced PP-Cl composites.