Effect of silicate materials on the structure, physicochemical properties, and gas-selective permeability of starch/PBAT films prepared by extrusion blowing

Abstract

This study investigates the effects of silicate materials, i.e. native diatomite, acid-treated diatomite, 1250-mesh meta-kaolin, 4000-mesh meta-kaolin and zeolite, on the structure, physico-chemical properties and gas-selective permeabilities of ‘blown’ starch/ poly (butylene adipate-co-terephthalate) (PBAT) films. Results revealed that silicate materials, particularly acid-treated diatomite, substantially enhanced the physico-chemical properties of the films. Films containing 1 % w/w silicate materials exhibited better physico-chemical properties than those containing 5 % w/w corresponding silicate materials. The tensile strength and elongation at break of films containing 1 % w/w acid-treated diatomite increased by 21.7 % and 22.2 %, respectively, relative to the control film. Compared with the control film, films containing these silicate materials exhibited significantly higher hydrophobicity and moisture resistance. Films containing 1 % w/w zeolite exhibited markedly improved gas selectivity, with their oxygen permeability reduced by 55.0 % and carbon dioxide permeability by 14.2 %, resulting in a gas selectivity ratio of 10.2 for carbon dioxide to oxygen. Moreover, packaging strawberries with films containing these silicate materials extended their shelf life, highlighting the efficacy of silicate materials in regulating the gas exchange through and enhancing the functional performance of the films. These findings suggest that starch/PBAT films containing silicate materials possess good application potential in fruit and vegetable preservation.