Silver/Copper Nanoparticle-Modified Polymer Chitosan/PVA Blend Fibers

In this study, chitosan (CS)/poly(vinyl alcohol) (PVA) (CS/PVA) blend nanofibers with varying weight ratios and silver (Ag)/copper (Cu)/CS/PVA composite fibers have been prepared successfully by the electrospinning process. The tip-to-collector distance was kept at 15 cm, and the applied voltage was varied from 15 to 25 kV. The effects of the weight ratios and applied voltage on the morphology and diameter of the fibers were investigated. The resultant fibers were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The SEM results showed that increasing the amount of chitosan in the CS/PVA blend resulted in a decrease in the fiber diameter from 162 to 89 nm while an increase in the voltage from 15 to 25 kV led to a decrease in the fiber diameters. Furthermore, the SEM results indicated that an increase in the fiber diameter from 161 to 257 nm was observed while morphological changes were also observed upon the Ag/Cu addition. The latter changes are perceived to be a result of increased conductivity and higher charge density.

Development and properties of bacterial cellulose, curcumin, and chitosan composite biodegradable films for active packaging materials

To deal with serious environmental damage resulting from plastic packaging materials, biodegradable films using natural products have gained considerable attention. Here, we provide a simple, fast, and environmentally-friendly route to construct a biodegradable film using chitosan (CS), bacterial cellulose (BC), and curcumin (Cur). Composite films (CSn-BC-Cur) using CS with different molecular weights were investigated, and their water moisture content (MC), water solubility (WS), contact angle (CA), mechanical properties, barrier properties, and antioxidant properties were compared. The obtained films were characterized by SEM, XRD, and TGA. The results showed that chitosan with a higher molecular weight presented higher contact angles and mechanical properties, along with a lower moisture content, water vapor transmission rate, and oxygen transmission rate. Furthermore, when the composite film was placed in 95 % ethanol, it released active substances. The results suggest that these composite films can be used as promising materials for food packaging.

Surface grafting of flax fibres with hydrous zirconia nanoparticles and the effects on the tensile and bonding properties

In the present study, a flax fibre yarn was modified through grafting of hydrous zirconia nanoparticles by hydrolysis of zirconium oxychloride solution, and the effects on the fibre and fiber-bonding properties were investigated. The grafting of the nanoparticles was confirmed by microscopy and spectroscopy analysis. The tensile and bonding strength to an epoxy resin (diglycidyl ether of bisphenol – F) of the modified flax fibres were tested with a single fibre tensile test and microbond pull-out test, respectively. Grafting of the nanoparticles onto the flax fibres brings in an obvious increase in the tensile strength and the interfacial shear strength of the flax fibre to the epoxy resin. An unidirectional flax fibre reinforced epoxy model composite was prepared by hand and characterized in terms of the thermo-mechanical and antimicrobial properties. Surface grafting of the flax fibre leads to an increase in the glass transition temperature and storage modulus, which is attributed to the enhanced bonding strength between the grafted fibre and the epoxy resin. In addition, the treated flax fibre-based composites expressed an antimicrobial performance. The study demonstrates that the fibre surface treatment with grafting of hydrous zirconia nanoparticles is a potential method to enhance the tensile and bonding properties of flax fibres.