Impact resistance and electrical conductivity of copper nanoparticle-<i>Milicia excels</i> sawdust composites

Abstract

Copper nanoparticles (Cu(NPs)) prepared by chemical reduction of cupper (II) sulphate pentahydrate using ascorbic acid were blended with Milicia excels (Odum) sawdust and Polyvinyl Formal/Calcium Carbonate wood adhesive as matrix to produce rectangular slabs of nano-composites with potential applications for industrial pack-aging or building panelling. The nano-composites were characterized by Fourier Transform Infrared (FTIR) Spec-troscopy, and hydroxyl (OH) groups -CH₂- (Alkane groups), C=C (Alkene or Aromatic groups), C-O (Carbonyl) groups of lignin, cellulose or hemicelluloses or C-O-C Ester groups of cellulose and hemicelluloses were identifi-ed. The mechanical toughness of the nano-composites were tested to determine the impact resistance, using Tinius Olsen IT 406 High Energy Pendulum Impact Machine. The impact energy of 26.89 ± 0.02 J exceeded values for individual constituents of the composites, was comparable to natural fibre reinforced composites, and the nano-composites could serve as panelling or packaging materials. The electrical characteristics of the nano-composites were examined by determining the electrical conductivity, resistivity and electric field strength, using simple dire-ct current Ohms bridge, and the values were respectively, (1.73 ± 0.05) x 10^-2 ohm^-1 m^-1, 57.8 ± 0.5 Ω m, and 186.3 ± 0.5 V m^-1. The low value of electrical conductivity was suggestive that the Cu(NP)-sawdust composite could be likened to intrinsic semiconductor, but the process for transition into extrinsic semiconductor was not in-vestigated. The imposed voltage increased with percentage moisture content, presumably due to hydrolyzed bon-ds on the surfaces of the nano-composite. The nano-composites could be used as insulating and packaging materi-als for sensitive electronic equipment.

Keywords: Cu(NPs), Ascorbic Acid, FTIR Spectroscopy, Polyvinyl Formal, Impact Test, Electrical Resistivity