Effect of Biochar on the Thermal and Dimensional Stability of Poly(Vinyl Chloride) (PVC) Composites

This study investigated the employment of biomass-derived biochar as performance-enhancing filler of PVC. Mechanical, thermal, rheological, and morphological properties were examined, with calcium carbonate (CaCO₃) used for comparison. Composites were prepared via melt processing followed by injection molding to generate test specimens. High filler concentrations caused significantly improved mechanical properties like tensile strength and modulus. At 23 wt.%, the biochar displayed similar tensile strength as the CaCO₃-filled composites, while providing weight reduction benefits, suggesting biochar could replace traditional fillers in construction materials. However, higher filler content beyond 23 wt.% led to a sharp decline in properties, indicating a limit to filler usage. Biochar addition also increased the composite's glass transition (T_g) and thermal stability. Due to their mechanical property performance, thermal permanence, and low carbon footprint, biochar can be a suitable and sustainable alternative reinforcing filler of PVC. Challenges, such as aggregation and poor interfacial adhesion, can be addressed by optimizing processing parameters, incorporation of compatibilizers, and tuning filler levels.