Impact of layer-by-layer self-assembly clay-based nanocoating on flame retardant properties of sisal fiber cellulose microcrystals

Abstract

The renewable cationic polyelectrolyte chitosan (CH) and anionic nanomontmorillonite (MMT) layers were alternately deposited on the surface of sisal fiber cellulose microcrystals (SFCM) via layer-by-layer (LBL) self-assembly method. The structure and properties of the composites were characterized by zeta potential, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometer (FTIR), microcalorimeter (MCC), and so forth. The zeta potential results show that the cellulose microcrystalline surface charge reversed due to the adsorption of CH and MMT nanoplatelets during multilayer deposition. MMT characteristic diffraction peaks appear in XRD patterns of SFCM(CH/MMT)5 and SFCM(CH/MMT)10 composites. Additionally, FESEM reveals that the SFCM(CH/MMT)10 surface is covered with a layer of material containing Si, which has been verified by elemental analysis. TGA results show that the initial decomposition (weight loss of 5%) temperature of SFCM(CH/MMT)5 is increased by 4°C compared to that of pure SFCM. On the other hand, carbon residue percentage of SFCM(CH/MMT)10 is 25.1%, higher than that of pure SFCM (5.4%) by 19.7%. Eventually, it is testified by MCC measurement that CH/MMT coating can significantly reinforce the flame retardant performance of SFCM.