Characterization and antibacterial properties of nanosilver-applied polyethylene and polypropylene composite films for food packaging applications

Nanocomposite films were developed using masterbatches of two polymers, namely low-density polyethylene (LDPE) and polypropylene (PP) containing silver (Ag) nanoparticles, by melt compounding and melt extruding. The films became increasingly yellow as the Ag content increased. Morphological evaluation showed the effective incorporation of Ag in the polymers. The Ag/LDPE nanocomposite film showed a comparable strength to that of commercial LDPE, although stiffness increased at high Ag (240 mg/kg) concentration. The Ag/PP nanocomposite film showed enhanced mechanical properties compared to commercial PP, although high Ag content (290 mg/kg) also resulted in weakening. Both nanocomposite films were effective against E. coli and S. aureus at concentrations of 36 and 30 mg/kg Ag nanoparticles for Ag/LDPE and Ag/PP films, respectively, resulting in a > 99.9% decrease in the number of viable bacteria. The antibacterial effect was more marked on S. aureus. The results obtained indicate that the nanocomposite films produced show great potential for developing antibacterial food packaging.