Central composite design based statistical modeling for optimization of barrier and thermal properties of polystyrene based nanocomposite sheet for packaging application

Abstract

Synergistic effect of ZnO-nanoparticles as three-dimensional nanospheres and nanoclay as one-dimensional clay platelets, on thermal and barrier properties of polystyrene-based nanocomposite packaging sheet was investigated. A central composite design under response surface methodology was employed for optimizing the thermal and moisture barrier properties of sheet. Polynomial equations were fitted to the obtained experimental data of glass transition temperature (Tg), water vapor permeability (WVP) and water uptake (WU) using multiple regression analysis with a determination coefficient values of 0.94,0.81 and 0.93, respectively. At 1.16 % ZnO and 4.47 % nanoclay concentrations, the corresponding predicted response values for Tg, WVP and WU were 111.88 °C, 7.75 × 10−11 g/m.s.Pa and 0.37 %, respectively, which were confirmed by validation experiments. The presence of nanoclay in the polystyrene/ZnO-nanoparticles matrix and increasing its content, increased UV absorption of the nanocomposite, while having little effect on transparency. The incorporation of nanoparticles reduced the oxygen permeability of polystyrene sheet by up to 60 %.