Correlation of the oxygen index with the results of assessing the flammability and combustibility of polymer composite materials obtained by small-scale methods
Authors:   National Research Moscow State University of Civil Engineering, USHKOV Valentin A. , KOPYTIN Andrey V. ,   Federal Center for Standardization, standardization and technical conformity assessment in construction, LANSKOY Pavel S. ,   National Research Moscow State University of Civil Engineering, USHKOV Maxim V. ,   National Research Moscow State University of Civil Engineering, SERKOV Boris B. ,   State Fire Academy of EMERCOM of Russia
Published: April 2024

PURPOSE. Most polymer composite materials (PCMs) are highly flammable, which significantly limits their use in the construction industry. Therefore, in the Russian Federation, much attention is paid to the development of effective methods for reducing the flammability of PCM. To assess the flammability and combustibility of PCMs, various small-scale methods are being studied, based on determining the temperature, thermal, concentration and kinetic parameters of combustion and flame propagation over their surface. This significantly complicates the analysis of scientific and technical literature. Therefore, the purpose of this work is to establish correlation between small-scale methods for assessing the combustibility and flammability of PCM. The objects of study were PCM for construction purposes (fiberglass, foam and polymer solutions) based on polymers of various chemical structures. METHODS. While assessing the flammability and combustibility of PCM, both GOST methods and methods described in the scientific and technical literature were used. Findings. Correlation has been established for the values of the oxygen index (OI) with the results of assessing the flammability of polymer composites using calorimetry methods and the flammability index Кср when tested by the “ceramic pipe” method, the values of the heat of combustion and the critical density of the ignition heat flux. For gas-filled polymers, OI = 30,18⋅Кср , which makes it possible to calculate the OI value of foam plastics based on the results of determining the flammability of materials using the ceramic pipe method. It is shown that with an oxygen index value of more than 26–27%, composites belong to moderately flammable materials, and with OI > 30% – for low-flammable materials. Data are presented on the influence of the chemical structure of oligoether methacrylates on the heat of combustion and oxygen index of cross-linked polyester methacrylates. It was revealed that the proportionality coefficient (A) in the equation OI/г = А/∆Hcг is different for individual homologous series of the studied polymers. At the same time, polymers of linear structure (polyethylene, polypropylene, polystyrene, polymethyl methacrylate) have lower values of coefficient A (2.68 kJ/g) compared to network polyether methacrylates (A = 2.86–3.27 kJ/g). RESEARCH APPLICATION FIELD. The established correlation of the OI values with the results of assessing the flammability and combustibility of PCM obtained by small-scale methods will make it possible to use the OI method in the development of fire-resistant PCM of a new generation. CONCLUSIONS. The established correlation between OI values and other indicators of flammability and combustibility of PCM will significantly reduce the amount of research in the development of composites for construction purposes. The results of the work can be used in various fields of science and technology.