Optimization of mechanical and color properties of polystyrene/nanoclay/nano ZnO based nanocomposite packaging sheet using response surface methodology

In this study, a new interesting ternary nanocomposite based on polystyrene (PS), nanoclay and zinc oxide nanoparticles (ZnO) has been suggested as a food packaging material. Effects of ZnO (0-2 wt%) and organoclay (Cloisite® 15 A) nanoparticles (0-7.01 wt%), on mechanical and color properties of the general purpose polystyrene (GPPS) sheets were quantitatively investigated using the response surface methodology (RSM). The structural features and surface morphology of resulted nanocomposites and the dispersion quality of nanoparticles in the polymer matrix were studied by scanning electron microscopy (SEM(and X ray diffraction (XRD) analysis. SEM and XRD results showed that the presence of ZnO nanoparticles improved the distribution of organoclay (OC) in the GPPS matrix and vice versa. Regression models were developed for ultimate tensile strength (UTS), strain at break (SB), Young's modulus (YM), lightness (L) inedx, yellowness index (YI) and whiteness index (WI) as a function of ZnO and organoclay concentrations. Linear and quadratic terms of regression models showed a significant influence on the UTS. In the case of L index, the linear term of organoclay and for SB, linear terms of both nanoparticles effects were significant. The optimized variables were found to be 0.81% ZnO and 0.57% organoclay for a maximum desirability of 0.805.