Hybrid Nanocomposite Films of Starch, Poly(vinyl alcohol) (PVA), Starch Nanocrystals (SNCs), and Montmorillonite (Na-MMT): Structure-Properties Relationship

摘要

Starch, as a natural, renewable, and biodegradable polysaccharide, is widely used in the food and pharmaceutical industries. However, the extreme water-sensitivity and poor tensile strength of starch materials have limited its practical application as an engineering material. Here, the authors blended starch with PVA to improve its film formability, and then, added Na-MMT and SNCs to the blend in order to enhance the mechanical properties. Nanofillers are used in pure and hybrid form to study the synergistic effect of these two types of nanofillers. SNCs, obtained by acidic hydrolysis of potato starch granules, have a z-average particle size of approximate to 230 nm and crystallinity of 57%. Nanocomposite films, prepared via the solution casting method, are characterized by X-ray diffraction (XRD) and tensile testing methods. XRD patterns confirmed the exfoliation dispersion of Na-MMT in the polymer blend matrix. Additionally, the results of the tensile tests and thermogravimetric analysis (TGA) indicated that the presence of nanofillers in separate and hybrid forms in the matrix led to the improvement of the mechanical and thermal properties of nanocomposites. Finally, the findings revealed the synergistic effect of nanofillers of SNCs and Na-MMT for improving the mechanical and thermal properties of starch/PVA blend, particularly in 3 wt% of the total filler content in 50:50 (w/w).