Characterization of the burning behavior of Ultra porous polyurethane-based aerogel: Impact of material properties on burning behavior

Abstract

This work details a hierarchical methodology to develop a pyrolysis model for ultra porous energy-efficient polyurethane-based aerogel (PU-aerogel). This methodology relied on simultaneous measurements of sample mass, back surface temperature (T_back), as well as sample shape profiles collected from controlled atmosphere pyrolysis apparatus (CAPA II) experiments. Based on the measured radiation-optical properties and the developed reaction mechanism, the thermal transport properties were determined based on the inverse modeling of these measurements. The resulting pyrolysis model was able to reproduce the sample shape profiles and T_back with an average accuracy of 10.5 % and 6.2 %, respectively. The model also predicted the burning rates of PU-aerogel at both radiative heat fluxes. An additional sensitivity analysis was conducted to systematically investigate the impact of input parameters on the burning behavior of PU-aerogel. The average MLR (avgMLR) and time to T_back = 533K ($t_{533K}$) of the CAPA II experiment under 60 kW m⁻² were defined as the model outputs. The density of the virgin material showed the most significant impact on changing avgMLR (-27.4 %) and $t_{533K}$ (108.7 %), followed by the density and thermal conductivity of intermediate components. The variations in material properties yielded a negligible effect on the time to peak MLR because the peak MLR of this specific material occurred very rapidly upon exposure. The findings of this work enabled the prediction of burning behavior of PU-aerogel and the design of a more flame-resistant PU-aerogel.