Mechanical behavior of transparent nanofibrillar cellulose–chitosan nanocomposite films in dry and wet conditions

Transparent, biocompatible and biodegradable chitosan (CS) nanocomposite films reinforced with nanofibrillar cellulose (NFC) were prepared by solution casting. The effects of NFC content on the mechanical properties in dry and wet conditions were investigated. The incorporation of NFC significantly enhanced the mechanical properties, especially in wet conditions. The ultimate tensile strength and Young׳s modulus of chitosan were improved by 12 times and 30 times, respectively, for the nanocomposite containing 32 wt% of NFC in wet conditions. The mechanism of the remarkable reinforcements was studied by analyzing the swelling behavior of NFC–CS nanocomposites. The mechanical properties of wet NFC–CS nanocomposite films matched well with those of human skin, which demonstrate potential for uses as artificial skin and wound dressings.