Stabilization of polyethylene with grape pomace extract: Effect of natural oil content

The winery waste of a white grape was extracted in two different ways to produce extracts, one containing the natural oil of the waste and one without it; the goal of the work was to determine the positive or negative influence of the natural oil content of the extract on its stabilization effect and efficiency. The polyphenol content of the extracts was moderate, but their DPPH assay proved their antioxidant effect. The two extracts were added to polyethylene in concentrations between 0 and 2000 ppm, and their stabilizing efficiency was determined in multiple extrusion experiments. The extracts stabilized polyethylene adequately; their efficiency was only slightly smaller than that of the commercial hindered phenolic antioxidant, Irganox 1010. The solubility of the extracts in PE is much larger, 280 ppm, than that of a flavonoid-type natural antioxidant, quercetin (15 ppm). The presence of the oil had only a slight effect on stabilization efficiency, and its influence on properties is more beneficial than harmful. It decreases interactions among polyphenol molecules, improves the processability of the polymer, and increases homogeneity slightly. Accordingly, an extraction step can be saved during the preparation of the product, thus offering an economic advantage.