Sustainable antibacterial PLA composites with nanocellulose acetate and essential oils: Performance and life cycle assessment

Antibacterial plastic films were fabricated via a simple two-step process by reinforcing poly(lactic acid) (PLA) with nanocellulose acetate and natural essential oils. Initially, cellulose acetate was synthesized from wood pulp waste under optimized conditions, achieving a 68.12% yield and a degree of substitution of 2.80. Ultrasonication produced nanocellulose acetate particles ranging from 164.2 to 396.1 nm. Incorporation of 8% nanocellulose acetate significantly enhanced the mechanical properties of PLA, increasing tensile strength from 16.93 MPa to 74.12 MPa. Subsequently, essential oils, including tea tree, cajeput, and eucalyptus, were added as antibacterial agents. Tea tree oil demonstrated the highest antibacterial efficacy, lowering OD600 cell density to 0.43 compared to 0.64 in PLA films without essential oil. The addition of essential oils also improved the films’ hydrophobicity and interfacial compatibility, as confirmed by SEM analysis and biodegradation testing. Life cycle assessment (LCA) further revealed that nanocellulose acetate and PLA synthesis stages contributed moderately to greenhouse gas emissions, at 7.30 and 12.60 kg CO₂ per kg of product, respectively.