Journal Article Develops Pyrolysis Model to Characterize the Burning Behavior of Ultra-Porous Polyurethane-Based Aerogel
The peer-reviewed journal article, “Characterization of the burning behavior of Ultra porous polyurethane-based aerogel: Impact of materials properties on burning behavior”, has been published in Combustion and Flame 272. Key findings from this study support the “Thermal Decomposition of Materials” research project, led by the Fire Safety Research Institute, part of UL Research Institutes. This paper was co-authored by FSRI research engineer, Mark McKinnon, as well as Yan Ding, Xinyang Wang, Grayson Bellamy, and Yu Wang.
Developing a Pyrolysis Model Through Hierarchical Methodology
Ultra-porous energy-efficient polyurethane-based aerogel (PU-aerogel) is a material with exceptional properties like low density, high porosity, and high resistance to heat flow. PU-aerogel is made through a novel manufacturing process which results in a rigid solid with a highly porous structure. Like many polymers, polyurethane produces combustible vapors when it increases in temperature and undergoes thermal decomposition, which poses a potential fire hazard when it is incorporated into insulation and façade assemblies. To better understand the associated risks, this study aimed to create a pyrolysis model that would predict the burning characteristics of this material, as PU-aerogels are known for their versatility and applications in various fields.
The methodology used to develop the model relied on measurements of sample mass, back surface temperature, and sample shape profiles collected during gasification experiments conducted with the controlled atmospheric pyrolysis apparatus (CAPA II). The pyrolysis model was able to reproduce the sample shape profiles and back surface temperature with an average accuracy of 10.5% and 6.2%, respectively, proving the model to have a fairly high level of accuracy. The model was also capable of predicting the burning rates of PU-aerogel over a range of heat fluxes consistent with fire-like conditions.
An additional sensitivity analysis was conducted to see how different factors would affect the burning behavior of the PU-aerogel. The density of the virgin material proved to have the most significant impact on how fast it burned, followed by the density and thermal conductivity of intermediate components.
The development of the pyrolysis model and the associated sensitivity analyses may be interpreted for the development of lower flammability PU foams and aerogels. This work provides theoretical guidance for developing a comprehensive pyrolysis model that may be used in the design of highly insulating PU-aerogel with reduced flammability. A product like this may promote energy efficiency and improved safety of the built environment, ultimately bettering the already popular insulating material.
“Ultra-porous combustible materials are becoming more common in the built environment as building designers strive for more energy-efficient construction. As a result, many highly porous polymer insulation products have been incorporated into new construction across the world. However, they are being incorporated without a comprehensive understanding of the burning behavior of these materials. In this work, we characterized the thermo-physical properties of a polyurethane aerogel, developed a burning model for the insulation material, and tested the sensitivity of the model to variations in input parameters. This research may lead to a safer built environment because of the generalized guidance it provides for the development of models to predict fire growth involving combustible insulation materials.”
– Mark McKinnon, FSRI, research engineer
To learn the full details about the materials and methods used, and a complete conclusion with recommendations for future work, visit the article here.
