Effects of various nanomaterials on the properties of starch/poly(vinyl alcohol) composite films formed by blow extrusion process

Effects of various nanomaterials on the physical and mechanical properties of hydroxypropyl distarch phosphate/poly(vinyl alcohol) (starch/PVA) composite films fabricated by blow extrusion were investigated. The starch/PVA nanocomposite films were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA/DTG), FTIR, and scanning electron microscope (SEM). The nanocomposite films containing nano-CaCO3 and organically modified montmorillonite (OMMT) showed the lowest and highest tensile strengths of 3.72 and 7.04 MPa, respectively. The film containing natural montmorillonite (MMT) exhibited the lowest elongation-at-break of 118.73 %. The film with OMMT exhibited the lowest water vapor permeability of 4.12 x 10(-10) g m(-1) s(-1) Pa-1. Addition of nano-TiO2 to starch/PVA films resulted in a significant decrease in Delta E* (increased clearness). Differential scanning calorimetry (DSC) indicated that the nanocomposite films exhibited higher glass transition temperatures (T-g) and lower melting enthalpy compared to the control film. Adding MMT and OMMT to starch/PVA blends increased the thermal stabilities of the films according to the TGA/DTG analysis. Agglomeration of particles was observed in the starch/PVA composite films containing nano-CaCO3 and nano-TiO2 while nano-SiO2 and MMT dispersed well in the matrix. On the whole, OMMT was more compatible with starch/PVA blends and served as a better nanomaterial to prepare starch/PVA nanocomposite films which was superior to that of the other four nanomaterials.