Combined Use of Titanium Dioxide Nanoparticles and Nanocrystalline Cellulose on Thermal, Hydrophobic and Color Properties of Starch-PVOH Bionanocomposites

The present study used a constant level of citric acid and polyvinyl alcohol and different amounts of nanocrystalline cellulose (CNC) and TiO2 nanoparticles to improve the properties of starch film. The effect of different amounts of glycerol was also examined. The results of differential scanning colorimetry demonstrated that the addition of CNC increased the melting and glass transition temperatures and the addition of high levels of TiO2 decreased the melting temperature and increased the glass transition temperature. The effects of these three compounds on the hydrophobicity and color of bionanocomposite plasticized starch were studied and their optimum values determined using a central composite design in response surface methodology. Water uptake data showed that the quadratic effect of TiO2 concentration and the linear and quadratic effects of CNC and GLY concentrations were significant. The optimum levels for TiO2, CNC and GLY for minimum water uptake were 0.118, 0.3 g and 1.36 ml, respectively. Quadratic CNC concentrations and linear glycerol concentrations were significant for water solubility. The optimum levels of TiO2, CNC and GLY for minimum water solubility were 0.235, 0.30 g and 1.36 ml, respectively. The CNC concentration had linear and quadratic effects on the yellowness index (YI) of the bionanocomposite. There was a significant interaction between TiO2 and GLY. The optimum levels of TiO2, CNC and GLY for minimum YI were as 0.235, 0 g and 1.06 ml, respectively.