Influence of TEMPO-oxidized NFC on the mechanical, barrier properties and nisin release of hydroxypropyl methylcellulose bioactive films

Bioactive films from hydroxypropyl methylcellulose (HPMC), nisin (N), and different percentage (5% to 75%) of TEMPO-oxidized nanofibrillated cellulose (NFC) isolated from rice straw pulp were prepared by solution casting technique and their properties were studied. Scanning electron microscope images (SEM) of films showed homogeneous surface with absence of nanofibers agglomeration. The mechanical and barrier properties were evaluated by measuring their tensile strength, tensile modulus, strain at maximum load, dynamic mechanical thermal properties (DMTA), and water vapor permeability (WVP). In all films, there was an improvement in the mechanical, thermomechanical, and moisture barrier properties as a result of presence of NFC. The molecular structure of the films was studied by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction patterns (XRD). Presence of NFC in HPMC films affected crystallinity of the later. The prepared HPMC/N, NFC/N, and HPMC/N/NFC films exhibited significant antimicrobial activities against Gram-positive bacteria Staphylococcus aureus with noticeable controlled release of nisin in case of films containing HPMC/NFC.