Effect of nano-biochar on mechanical, barrier and mulching properties of 3D printed thermoplastic polyurethane film

In this research work, the nano-biochar/thermoplastic polyurethane (TPU) nanocomposite mulching films were successfully prepared by fused deposition modelling (FDM) process. The biochar was prepared by pyrolysis of digitalis purpurea plant at 400 ℃ and the size of biochar was reduced to 80 nm by ball mill method. Various concentrations (0, 2, 4, 6, 8, 10 wt%) of nano-biochar was blended with TPU and the extrusion filament was prepared. The FDM printer was used for the preparation of single-layer mulching films with the thickness of 0.4 mm. The addition of various concentrations of nano-biochar increased the surface colour difference from 14.48 to 63.07 and decreased the light transmittance from 82 to 21%. The hydrophobic properties of nanocomposite mulching films were increased by the incorporation of nano-biochar and the highest value of 116° was achieved for 10 wt% of nano-biochar. The porosity of the films was decreased from 0.7 to 0.2% and the water absorption was increased from 0.1 to 0.43% for 48 h. The tensile and tear strength of the films were increased to 38 MPa and 4.1 MPa. The maximum penetration and impact resistance of 26.7 N and 279 g was achieved for 10 wt% of nano-biochar. The burst strength was increased from 78.2 to 94.5 kPa. The OTR and WVTR was decreased from 1765.45 to 1011.34 cc/m day.atm and 19.4 to 11.9 g/m day. The lowest frictional coefficient of 0.3 and minimum soil temperature was attained for 10 wt% of nano-biochar.