Advancing food packaging: enhancing stability and performance of biodegradable PHBHHx with ZnO nanofillers

This paper aims to investigate the optimal formulation of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx)/ZnO bionanocomposites for food packaging applications with respect to filler content ratio. Bionanocomposite samples prepared by melt-compounding at various ZnO-NPs contents (1.5, 3, and 6 wt%) were evaluated in terms of optical, thermal, viscoelastic, and mechanical properties. UV–Vis spectroscopy revealed a significant enhancement in the photochemical stability of PHBHHx/ZnO bionanocomposites compared with neat PHBHHx, which exhibits a strong absorption band at wavelengths below 380 nm, thus confirming the anti-UV activity of ZnO nanoparticles. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) demonstrated improved thermal stability and increased stiffness/mechanical strength with increasing ZnO-NPs content. Notably, the bionanocomposite with 3 wt% of ZnO exhibited the most substantial improvements, with a 20% increase in thermal decomposition temperature and a 30% increase in storage’s modulus at room temperature than the neat PHBHHx. Moreover, a decrease in loss modulus ( E ″) and tan δ indicated reduced energy dissipation and enhanced material elasticity. Overall, incorporating 3 wt% ZnO nanoparticles into PHBHHx resulted in a bionanocomposite with superior photochemical stability, thermal stability, and viscoelastic properties compared to both neat PHBHHx and other bionanocomposite samples, which makes it as a promising candidate for food packaging applications.