Polymer processing and characterization of LLDPE films loaded with α-Tocopherol, quercetin, and their cyclodextrin inclusion complexes

Natural antioxidant additives were compounded into linear low-density polyethylene (LLDPE) using a twin-screw counter-rotating mixer and compression molded into films. Manufactured LLDPE films contained 2715 mg kg^-1 α-tocopherol in its free and β-cyclodextrin complexed form and 1950 mg kg^-1 quercetin in its free and γ-cyclodextrin complexed form. Both cyclodextrin complexes were loaded into films at 1.5% by weight. These natural antioxidants were incorporated into LLDPE resins with two different catalyst types, Ziegler-Natta and metallocene. Films were characterized by optical microscopy, oxidation induction time (OIT), oxygen transmission rate, contact angle analysis, and atomic force microscopy (AFM). All antioxidant additives increased the oxidative stability of LLDPE as measured by increased OIT, particularly quercetin. Natural antioxidants and their cyclodextrin inclusion complexes may provide a dual function in packaging to protect the polymer from oxidative degradation during melt processing and to delay the onset of oxidation of the packaged food during storage.