Sustainable eco–composites obtained from waste derived biochar: a consideration in performance properties, production costs, and environmental impact

Waste based activated biochar was used to manufacture wood/polypropylene biocomposites. The biochar used had no surface functional groups, however, possessed high surface area (335 m2/g). Therefore, it was hypothesised that less than usual amount (3–5 wt%) of compatibiliser (maleic anhydride) could be used, to reduce production costs, while maintaining similar mechanical and flammability properties of the biocomposite. The biocomposites were characterised mechanically through tension, flexural, impact, and micro–hardness tests. The flammability and thermal behaviours were determined using cone calorimetry and thermogravimetry, respectively. Infrared spectroscopy and X–ray diffraction were also employed to comprehend the chemical changes occurring in the biocomposites. It was found that the amount of compatibiliser could be reduced to 1 wt% (from 3 wt%) without compromising on the mechanical performance (especially, tensile strength/modulus, impact strength, and micro–hardness) and flammability properties of the biocomposites. Electron microscopy revealed that the lack of compatibiliser in the biocomposites was compensated by well–dispersed biochar particles whose pores were infiltrated by the polymer causing a mechanical interlocking. In general, addition of biochar improved the mechanical and fire performance of the biocomposites compared to the neat polymer. Reduction of compatibiliser to 1 wt% from 3 wt% in conjunction with biochar saves ∼18% of the biocomposite production costs. [Display omitted] •Waste based biochar was used to manufacture wood/polypropylene biocomposites.•Biochar lacked surface functional groups.•Compatibiliser amount was gradually reduced in the biocomposites from 3 to 0 wt%.•Compatibiliser can be lowered to 1 wt% without compromising performance properties.•Lowering of Compatibiliser to 1 wt% saves 18% of production costs.