Effects of Thymol Individually or Encapsulated in Chitosan Phosphate on the Properties of Poly(lactic acid) and Poly(butylene succinate) Matrix Reinforced with Nanofibrillated Cellulose

Abstract

Thymol, a natural active compound, is recognized for its remarkable antimicrobial properties, making it a suitable choice for active agents in food packaging applications. This study focuses on the encapsulation of thymol in chitosan phosphate nanoparticles (CNP) to overcome its limitations, particularly volatility, and incorporates it into bio-nanocomposite films via solvent casting. Moreover, comparison of the effects of pure thymol, CNP, and encapsulated thymol-loaded chitosan phosphate nanoparticle (TCNP) on the film’s properties were also assessed. The film’s chemical interaction (Fourier transform infrared, FTIR), thermal, mechanical, light transmittance, water barrier, antibacterial, toxicity properties, and release test were evaluated. The results disclosed that the incorporation of 5 wt% of TCNP1.0 into the PLA/PBS/NFC films matrix improved thermal stability (0.76%), tensile strength (46.8%), and enhanced water barrier properties, as evidenced by a reduction in water vapor permeability (WVP) by 10.1%. The FTIR analysis demonstrated the presence of intermolecular hydrogen bonds, indicating the compatibility between TCNP and the PLA/PBS/NFC matrix. The bio-nanocomposite films also exhibited noteworthy antibacterial effects and had an inhibitory rate against S. aureus. In summary, bio-nanocomposite films have significant potential as an antibacterial agent in the advancement of innovative bio-based active packaging systems.