Synthesis and study of mechanical and fire retardant properties of (carboxymethyl cellulose -g-polyacrylonitrile)/montmorillonite biodegradable nanocomposite

Despite abundant researches on petroleum based polymer nanocomposites over micro and macro composites, these nanocomposites suffer from deprived biodegradability, highly inherent flammability and less mechanical strength. The present work describes the preparation of a biodegradable nanocomposite based on carboxymethyl cellulose-g-polyacrylonitrile (CMC-g-PAN) and montmorillonite (MMT) nanoclay by using ammonium persulfate (APS) as an initiator, methylene bis-acrylamide (MBA) as a crosslinker via emulsifier free emulsion polymerisation. The formation of the nanocomposites was confirmed by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and Transmission electron microscope (TEM) analysis. The formation of CMC-g-PAN copolymer was confirmed by means of proton nuclear magnetic resonance (¹H NMR) spectra. The improvement in thermal stability of the nanocomposites over copolymer was outstanding. More importantly, incorporating MMT enables the nanocomposite to achieve a dramatically reduced peak heat release rate of 536?±?03 kW m^?2 shown in cone calorimetry tests and higher limiting oxygen index (LOI) value indicating improved fire retardancy. In addition, the tensile strength of the nanocomposite was also increased by around 41% with 5% w/v MMT contents. This is explained on the basis of strong interfacial adhesion between CMC and MMT through PAN. Meanwhile for its better commercialization, the eco-friendly nature was studied via biodegradation.