Comparative study on the properties of nanopapers prepared from cellulose and chitin nanofibers

  During last two decades, nano-biomaterials like cellulose nanofiber (CNF) and chitin nanofiber (ChNF) have attracted the attention of many researchers to make different products. The most important properties of these nanomaterials are bio-compatibility, bio-degradability, renewability, owning cheap available raw materials, owning high mechanical properties and safety. Based on these promising properties, a wide variety of applications have been created for these nanomaterials. One of these products is transparent and tough nanopaper in which hydrogen bounds are created among nanofibers with no adhesive or additives. In recent years, many researchers have been focused on the production, optimization of properties and utilization of CNF and ChNF nanopapers in different applications. Based on the technical and functional properties of CNF and ChNF and nanopapers, as well as the necessity of doing more investigation and evaluation on these nano-materials and nano-products for the future researches and applications, it was aimed to compare the properties of CNF and ChNF nanopapers in this study. To do this research, CNF and ChNF gels were prepared from Nano Novin Polymer Co. (Iran). To make nanopapers, the gels were first converted to mat using vacuum filtration process and then the mats dried in a vacuum oven at 70 °C for 24h. The fabricated CNF and ChNF nanopapers were characterized using atomic force microscope (AFM), qualitative transparency, X-ray diffraction (XRD), tensile, and air permeability tests. The results showed that the average diameter of CNF and ChNF was 35 and 26 nm, respectively. The nanopapers prepared from both CNF and ChNF showed complete barrier properties against air. The XRD curves of CNF and ChNF nanopapers were completely different. The crystallinity index of CNF and ChNF nanopapers obtained were 68% and 90%, respectively. The tensile strength, Young’s modulus and strain of ChNF nanopaper were higher than those of CNF nanopaper. CNF and ChNF are both nanomaterials simultaneously owning the most important technical, economic and environmental properties. Also, the nanopapers made from these nanofibers showed promising physical and mechanical properties including complete barrier properties to air, high transparency, and mechanical properties; hence, based on these promising properties and ongoing intensive researches on this product, CNF and ChNF expects to be used in a wide varieties of applications including medicine, papermaking, electronic, magnetic, food packaging, etc. Keywords: Cellulose nanofiber, Chitin nanofiber, Nanocellulose nanopaper, Physical properties, Mechanical properties