Development of kinetic parameters for polyurethane thermal degradation modeling featuring a bioinspired catecholic flame retardant

A recently developed flame retardant (FR) nanocoating of polydopamine (PDA) was applied to flexible polyurethane foam (PU) and thermogravimetrically analyzed (TGA). Thermal degradation kinetics were described by a simplified multi-component, Arrhenius expression coupled with a first-order reaction model. Kinetic parameters were then extracted via an optimization solver. By limiting the number of optimized parameters, a mesh adaptive direct search algorithm was employed to extract meaningful kinetic parameters that better simulate the TGA data compared to graphical methods. Through TGA, it was shown that the effect of the PDA nanocoating on PU degradation differs between oxidative (78 vol% nitrogen (N2) and 21 vol% oxygen) and inert (100% N2) environments. In nitrogen, the mass loss is delayed and diminished in the first PU reaction, which is the opposite effect of a traditional halophosphate FR. In an oxidative environment, the first reaction of PU is greatly delayed by the PDA coating, but once the reaction begins, it becomes accelerated.