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 × 10−10 g m−1 s−1 Pa−1. Addition of nano-TiO2 to starch/PVA films resulted in a significant decrease in ∆E* (increased clearness). Differential scanning calorimetry (DSC) indicated that the nanocomposite films exhibited higher glass transition temperatures (Tg) 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.