Design and engineering of novel extrusion-cast films from plasticized cellulose acetate filled with mineral fillers for flexible packaging applications

Abstract

Plasticized cellulose acetate (pCA)-based green composite films were fabricated via cast film extrusion as sustainable alternatives to solvent-cast processing and conventional petroleum-based plastics for applications in flexible packaging. Cellulose acetate was plasticized with bio-based triacetin (pCTA) or petrochemical triethyl citrate (pCTEC). Green composites were then prepared by incorporating 10 or 15 wt% talc or recycled CaCO₃ (rCaCO₃) with an optimized amount of Luperox (LUP) used as a compatibilizer. The combined addition of fillers and LUP significantly enhanced the elastic modulus (EM) of all samples, particularly for talc-filled systems. Specifically, EM increased by 126% in pCTA/LUP/15Talc and by 136% in pCTEC/LUP/15Talc compared with pCA. The tensile strength (TS) also improved by 31–40% in talc-filled films, while rCaCO₃-filled films showed minimal changes. These enhancements were attributed to improved interfacial adhesion between talc and pCA, promoted by LUP as well as orientation of talc crystallites and polymer chains during cast film extrusion. X-ray diffraction confirmed the higher nucleating efficiency of talc, yielding higher crystallinity values of 75–84% for talc-filled versus 66–69% for rCaCO₃-filled pCA. Talc-filled films also exhibited superior elongation at break (EB), thermal stability, and barrier performance, with oxygen and water vapor permeability reductions of up to 38% and 72%, respectively. Talc-filled films’ higher contact angles (for both water and diiodomethane) and lower surface energy further supported the improved barrier properties. Overall, the synergistic effects of LUP and talc significantly enhanced the mechanical strength, barrier effectiveness, and thermal stability of pCA composites, demonstrating their strong potential as sustainable materials for flexible packaging applications.