Nanoindentation assisted analysis of biochar added biocomposites

Biochar produced from the pyrolysis of waste pine wood was employed to manufacture wood/polypropylene biocomposites. Mechanical properties of micron-sized biochar particles were investigated and compared with those of waste pine wood and neat polypropylene particles by nanoindentation technique. An attempt was made for nanoindentation-assisted prediction of comprehensive mechanical properties of the resulting biocomposites. Theoretical models (i.e. rule of mixtures, Halpin-Tsai-Nielsen, and Verbeek) were applied using the nanoindentation properties of individual constituent particles to calculate the bulk properties of biocomposites. Good agreement was observed between the predicted and experimental moduli values. The hardness prediction through rule of mixtures correlated well with the Vicker's hardness test values. The nanoindentation hardness values of individual components follow an order: biochar (0.43 GPa) > wood (0.3 GPa)> polypropylene (0.1 GPa), whereas the moduli values are 1.5, 5.6, and 4.9 GPa for polypropylene, wood, and biochar, respectively.