Green bio-based aerogels prepared from recycled cellulose fiber suspensions

Abstract

Recycled cellulose fibers (RCF) from waste paper were utilized to prepare bio-based aerogels through an environmentally friendly freeze-drying method. Food thickening agent sodium carboxymethyl cellulose (CMC) served as a matrix in the bio-aerogels. The microstructures and mechanical properties of the aerogels have been studied as a function of RCF/CMC content. Sodium montmorillonite (Na⁺-MMT) and ammonium polyphosphate (APP) were added to enhance the thermal stability and flame retardancy, which were investigated by thermogravimetric analysis (TGA) and cone calorimetry respectively. It was found that the Na⁺-MMT significantly improved the fire retardancy of the aerogels and APP played a synergistic effect with it. The initial decomposition temperature increased by 15 °C and the peak of heat release rate decreased from 90 to 49.5 kW m⁻² in the presence of 33% clay. Addition of APP further increased the residue amount and reduced the fire growth rate. Fourier transform infrared spectroscopy (FTIR) was used to analyse the char formed after cone calorimeter tests.