Enhanced Thermal Stability of Tunicate Cellulose Nanofibers by Inorganic Nanocomposites

As the environmental pollution caused by microplastics deepens, there is increasing interest in environmentally friendly materials that replace conventional persistent plastics. Cellulose is a natural-derived biodegradable material that can be extracted from wood, plant, algae, tunicate, bacteria and the others. Tunicate cellulose has excellent mechanical properties, high crystallinity and high aspect ratio. Nanocellulose has lower density, higher crystallinity, and wider specific surface area than conventional cellulose, while maintaining hydrophilicity and biodegradability with excellent tensile strength and crystallinity. It has attracted great interest in academia and industry. However, thermal decomposition at low temperatures limits the use of nanocellulose. It is known that general cellulose decomposes at 350 degrees C, but in particular, nanocellulose produced by oxidation or strong acid treatment changes the surface functional group of cellulose nanoparticles and exhibits a lower thermal decomposition temperature than pristine cellulose. Tetraethyl orthosilicate (TEOS) was synthesized with Tunicate cellulose-nanofibers (CNFs) aqueous solution via stober process, and the surfaces of CNFs were chemically coated with silica nanoparticles. The fabricated CNF/SiO₂ nanocomposites solution was produced to a film form by vacuum filtration. The morphology, structure, thermal resistance and flame retardance of CNF/SiO₂ nanocomposites were investigated through scanning electron microscopy (SEM), transmission Electron Microscope (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA). The TEM images showed that the silica nanoparticles were thinly coated on the CNFs surfaces. TG-DTA curve reveals the thermal decomposition temperature of the silica-coated CNF nanocomposites is delayed.