In this experiment, the oxide nanoparticles were synthesized via chemical precipitation and the nanocomposites were produced using in situ polymerization method with varying nanoparticles contents ranged from 0.1 g to 1.0 g for electrical conductivity and from 0.05 g to 0.25 g for thermal conductivity. The electrical and thermal conductivities of nanocomposites were investigated and compared with the values obtained for untreated polystyrene. It was observed that the electrical and thermal properties were higher for the nanocomposites and increase with increasing nanoparticle concentrations in the samples. It can be observed that nanocomposite containing NiO nanoparticles gave a better electrical and thermal conductivity followed by nanocomposite containing BaO nanoparticles and nanocomposite containing Sb2O3 nanoparticles respectively. It can also be observed that nanocomposite containing NiO nanoparticle showed increase in rate of heat transfer from 1.60 W to 2.60 W, while nanocomposite containing BaO nanoparticles recorded increase in rate of heat transfer from 1.40 W to 2.45 W and nanoomposite containing Sb2O3 nanoparticle showed increase in rate of heat transfer from 1.07 W to 2.21 W, as concentration of nanoparticles increased from 0.05 g to 0.25 g respectively. Conclusively, with these results, the nanocomposite containing NiO nanoparticles gave a better thermal and electrical conductivity by having a better conducting filler network inside the matrix than nanocomposite containing BaO nanoparticles and nanocomposite containing Sb2O3 nanoparticles. It is recommended that during the production of polymer nanocomposite, PS/NiO, PS/BaO and PS/Sb2O3 nanocomposites could be used in electrically conductive devices as well as suitable materials for heat transfer applications.

In this experiment, the oxide nanoparticles were synthesized via chemical precipitation and the nanocomposites were produced using in situ polymerization method with varying nanoparticles contents ranged from 0 to 5 g. The mechanical properties of the nanocomposites were investigated and compared with the values obtained for untreated polystyrene. It was observed that the mechanical properties were higher for the nanocomposites and increase with increasing nanoparticle concentrations in the samples. It can be observed that the untreated polystyrene gave a tensile strength of 945.25 N/mm2.  At high nanoparticle content of 5 g, the nanocomposite containing NiO nanoparticles showed a tensile strength of 973.83 N/mm2 while nanocomposite containing BaO nanoparticles gave a tensile strength of 968.19 N/mm2 and nanocomposite containing Sb2O3 nanoparticle gave a tensile strength of 955.53 N/mm2. The results indicate that the tensile strength and percentage elongation of all the nanocomposites improved with the addition of metal oxides nanoparticles compared with the untreated polystyrene. Slight decrease in percentage reduction in area of the nanocomposites was recorded. Conclusively, with these results, the PS/NiO nano composite showed a better trend of behaviour due to better interfacial interaction between the nanofillers and the polymer matrix followed by PS/BaO and PS/Sb2O3 nanocomposites. It is recommended that during the production of polymer nanocomposite, PS/NiO, PS/BaO and PS/Sb2O3 nanocomposites could be used as reinforcements in the construction of buildings to add structural stability to the building.