New Silica Fillers for Polymers used in Food Packaging

Abstract

SummarySeveral nanosilicas with different degree of hydrophobicity were prepared from tetraethyl orthosilicate (TEOS) by using the sol‐gel method. Two modifiers, 3‐aminopropyl triethoxysilane (APS) and 1,1,1,3,3,3–hexamethyldisilazane (HMDS), were added during the synthesis. The nanosilicas were added to commercial biopolymer (Hexamoll Dinch, BASF) intended for packaging of apples and pears. The nanosilicas were characterized by X‐ray diffraction, transmission and scanning electron microscopies, potentiometric titration, porosity and specific surface area, and hydrophobicity/hydrophilicity by wetting tests. Colorimetry was used to assess the effect of the nanosilica in contact with apple pulp as the change in color with time was related to the efficiency of the packaging material. Addition of nanosilicas obtained with HMDS and APS increased the hydrophobicity of the biopolymer. The APS modified nanosilica showed an abrupt decrease in acidity as compared to the unmodified silica (i.e. the one prepared with only TEOS). On the other hand, the increase in HMDS maintained the spherical shape of the silica which also was maintained into the biopolymer. On the other hand, the nanosilica morphology was similar in the biopolymer materials, forming clusters or agglomerates. Finally, the brightness of the pieces of apple pulp in contact with the modified nanosilicas slightly increased with respect to the unmodified silica, and similar behavior was observed in the Hue angle.