Colloidal Gibbsite Nanoparticle/Polyacrylamide Composites for Flame-Retardant Materials

Abstract

Two-dimensional (2D) nanomaterials have many potential applications. Herein, 2D colloidal gibbsite (GS) nanoparticles, [?-Al(OH)(3)], dispersed easily in water, are used as an effective filler for polyacrylamide (PAM) to improve their thermal degradation behaviors for applied fields in flame retardants. A composite containing 10.0 wt % GS retains more than 30.8 wt % noninflammable residues after pyrolysis (900 degrees C). The kinetics and thermodynamics of PAM and GS/PAM have been elaborately investigated using thermogravimetric analysis for the first time. The kinetic (activation energy, pre-exponential factor, reaction order) and thermodynamic (?H, ?G, ?S) parameters during the major decomposition zone (330-460 degrees C) are determined by applying Van Krevelen, Horowitz-Metzger, Coats-Redfern, Broido, Madhusudanan, Arrhenius, and Bagchi models. The results show that as the content of GS or acrylamide in composites increases, their activation energy increases or decreases, respectively. For a composite containing 10.0 wt % GS and 30.0 wt % acrylamide, compared to PAM, the activation energy reaches the highest value of 362.720 kJ/mol, the ignition time is 125 s longer, and the peak heat release rate and total heat release diminish by 44.5 and 68.8%, respectively. The presence of a kinetic compensation effect is also evident. The as-prepared GS/acrylamide is an aqueous dispersion and is hence easily surface-coated onto other flammable foams or materials by blade-coating or dipping. Our studies contribute to understanding 2D GS-blended nanocomposites in their applications as flame retardants or fire-resistant membranes.