Search

In this study, active biodegradable films from chitosan (CS) containing 5% w/w Origanum vulgare ssp. gracile essential oil (EO) and 4% w/w cellulose nanofibers (CNF) or lignocellulose nanofibers (LCNF) as nanoreinforcement were developed. GC–MS analysis showed that the most components of EO were carvacrol (49.43%) and then γ-terpinene (17.71%). The CS-EO film had high antioxidant activity and was more effective against E. coli and B. cereus bacteria than bionanocomposite films, which shows the release controlling effect of CNF and LCNF on the bioactive compounds from CS films. EO had not significant effect on the mechanical properties of the films (p > 0.05), while nanofibers had significant effects (p < 0.05) on strain to break (STB) and ultimate tensile strength (UTS). Incorporation of EO and CNF/LCNF in the CS-film also considerably improved solubility and water vapor barrier properties of the films. Color properties were significantly affected by adding of EO and CNF/LCNF. Formation of new hydrogen bonds between the chitosan chains, the EO and nanofibers were confirmed using FT-IR spectroscopy. Morphology of films was viewed using AFM and SEM, suggesting good dispersion of the CNF/LCNF. In general, the properly dispersion state and improving effect of LCNF on properties of CH-EO films was more than CNF. [ABSTRACT FROM AUTHOR]

The effects of silver nanoparticles (AgNPs) at 1% wt. and different concentrations of chitin nanofiber (CHNF) (1.5–6% wt.) on tensile properties, water vapor permeability (WVP), solubility, swelling, color properties and morphological characteristics of chitosan nanocomposite films were studied. FTIR results confirmed that the affinity of CHNF for interaction with chitosan chains is more than AgNPs. SEM images showed that CHNF was uniformly distributed in the polymer matrix. X-ray diffraction confirmed that the degree of crystallinity was increased by addition of 6% CHNF. Response surface methodology (RSM) was used to determine the optimum amount of CHNF as nano filler. The optimization was based on maximizing tensile strength, Young’s modulus, elongation at break, L* and decreasing WVP, solubility and swelling. The results showed that the AgNPs had a negative effect on mechanical and color properties of chitosan films. But incorporation of CHNF improved their mechanical and barrier properties significantly. Lowest WVP, solubility and swelling of nanocomposite films were respectively for 6, 2 and 2% wt. of CHNF content. Considering all physical and mechanical parameters, the optimal value calculated for CHNF, was 4.55%. [ABSTRACT FROM AUTHOR]