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

Plasticized cellulose acetate (pCA)-based composite films were fabricated via hot-melt cast film extrusion as a sustainable alternative to both solvent cast processing and conventional non-biodegradable plastics, for flexible packaging applications. Low-acetyl content cellulose acetate (CA) was plasticized with bio-based triacetin (pCTA) or petrochemical triethyl citrate (pCTEC). Then, composite films were developed from pCA reinforced with 10 or 15 wt% talc or recycled CaCO₃ (rCaCO₃), within a small amount of Luperox as a compatibilizer. Talc-filled pCTEC composites exhibited the best performance, with elastic modulus and tensile strength improvements of up to 136% and 40%, respectively, over neat pCTEC films. These enhancements were attributed to improved filler-matrix adhesion, strain-induced crystallization, and increased crystallinity. In terms of thermal stability, TmaxTEC (315.37 °C) greatly surpassed TmaxTA (226.25 °C) and this trend maintained across all pCTEC-based composites. Moreover, talc-filled pCTEC composites provided superior barrier properties than pCTA-based composites, reducing oxygen and water vapor permeability by up to 38% and 72%, respectively, compared to neat pCTEC film. These results underscore the potential of pCA-based composites for sustainable flexible packaging applications.