Poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/cellulose nanocrystal films: artificial weathering, humidity absorption, water vapor transmission rate, antimicrobial activity and biocompatibility

Abstract

Bionanocomposite films of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with different cellulose nanocrystal (CNC) loadings were prepared. Effects of artificial weathering, humidity absorption, water vapor transmission rate (WVTR), antimicrobial activity and biocompatibility were studied. Differential scanning calorimetry (DSC) and time resolved synchrotron X-ray diffraction were used to provide information about the effect of CNC on the crystalline structure of PHBV in the bionanocomposites. The incorporation of CNC accelerated the crystallization rate of PHBV due to a nucleating effect. DSC results showed first a decrease of crystallization and then the occurrence of secondary crystallization after artificial weathering. Scanning electron microscopy images implied well CNC distribution before artificial weathering and formation of blister—like points due to artificial weathering. Hydrophobicity of bionanocomposites was found to be slightly lower than for the PHBV in the humidity absorption tests. Bionanocomposites exhibited smaller WVTR due to restricted PHBV chain mobility. Samples with zinc oxide and silver showed antimicrobial inhibition activities against S. enterica, L. monocytogenes, S. aureus and E. coli. Results of cell viability and nitrite accumulation tests showed that PHBV and its bionanocomposites were biocompatible.