Effect of cold plasma on the physical and mechanical properties of nanopapers prepared with cellulose and chitin nanofibers

The last two decades witnessed more interest for using bio-based products. This study was aimed at studying and comparing the effects of cold plasma on the physical and mechanical properties of nano-films prepared from wood-driven and bacterial cellulose nano-fiber hydrogels. Biopolymers of polysaccharides have been widely evaluated due to their advantages in eco-friendliness and biodegradability.

Cellulose-based materials are generally utilized as a result of their biocompatibility, edibility, plenitude in nature, excellent barrier properties and low cost. Bacterial Cellulose Nano-fiber (BCNF), a biopolymer combined by microorganisms. BCNF has special physical, mechanical, and chemical properties. Chitin, the second amplest normal polymer after cellulose. The great capacity of film framing and natural antimicrobial movement of chitin makes its potential promising for improving the most up to date antimicrobial bundling ideas. Non-thermal plasma treatment is an effective and broadly utilized method for fitting the surface of materials' wide assortment. The effect of cold plasma on the properties of films prepared from wood driven and bacterial cellulose nano-fibers as well as chitin nano-fiber hydrogels has been evaluated in this study. The different mentioned nano-films were exposed to cold plasma at four-time levels of 0, 3, 6 and 9 minutes. Nano-films product with vacuum filtration method. Morphologic properties of nano-films studied with Scanning electron microscope. In this study nano-films properties consist of thickness, weight, density, water vapor permeability (WVP), water solubility, nano-films surface color, light transmission and transparency, films mechanical properties were measured.

SEM photography showed the homogeneous and uniform structure of bacterial cellulose. Plasma treatment removes loosely bound low molecular weight fragments. Wood cellulose had the strongest structure compared to other nano-films, and it needed a higher peak force for the breakdown. Chitin nano-films had the porous structure. Cold plasma decreased weight, density, solubility, light transmission and etc. of films but it increased their water content. Chitin nano-films had a higher extension (0.63mm), tolerable stress (50.99MPa), elongation (2.12%), elastic modulus and tensile strength. When nano-films were exposed to the cold plasma for a long time, their elastic modulus was decreased considerably. Using mechanical and bacterial synthesized cellulose, Nano-films had the highest and lowest TS mean, respectively. Nano-films without exposure to cold plasma had the highest TS means. When nano-films were exposed to cold plasma, their TS values were decreased.

Atmospheric cold plasma treatment resulted in enhanced water vapor hindrance and mechanical properties films appropriate to the polar group and crosslinking site organization on the film's surface and besides increase surface roughness.