Abstract

Starch is a natural polymer which, due to its renewability, biodegrability, availability and a relatively low cost, has a high potential for applications in biodegradable materials. However, because of its hydrophilic nature, the number of commercially available starch-based products is still limited. Recently, starch-based nanocomposites with the addition of clay minerals as nanofillers have given rise to large-scale improvements in physical, mechanical, and barrier properties. In our studies, potato starch-clay nanocomposite films were prepared using a solution casting technique. The effect of different types of clays as nanofillers of the hydrophilic Cloisite® Na+ and Nanomer® PGV, or of hydrophobic NanoBent ZR-1 and Nanofil® 2, on the structure as well as thermal, mechanical and barrier to water vapor properties of the obtained films was determined. It was observed that the starch-Cloisite® Na+ nanocomposite showed an intercalation of starch in the silicate layers due to interactions of the hydroxyl groups of the polymer with the sodium ion of the clay or with its edge hydroxyl groups, which, however, did not improve neither thermal, mechanical nor water barrier properties of starch-Cloisite® Na+ nanocomposite films as compared to the unmodified starch film. The latter showed melting temperature (Tm) of 176°C, tensile strength (σ) of 30.2 MPa, elongation (ε) of 3.8%, and water vapor permeability (WVP) of 0.43 g•mm•kPa-1•h-1•m-2. It was found that the addition of 5% hydrophilic nanofillers, in contrast to those of hydrophobic nature, decreased the film melting temperature, while the addition of 10 and 15% of the nanofillers resulted in an increase of Tm.

Authors (5)