Assessment of temperature and duration of high-temperature exposure to polymeric materials for the diagnosis of secondary fire sources

Introduction. The problem of differentiating between primary and secondary fire sources is quite pressing when diagnosing secondary fire sources during forensic fire investigations. The complexity of the task lies in the need to simultaneously determine two independent variables — temperature and duration of high-temperature exposure. Solving this complex problem is a pressing research objective.

Goals and Objectives. The purpose of this paper is to develop a method for assessing the temperature and duration of high-temperature exposure to polymeric finishing materials. To achieve this, specimens of finishing building materials exposed to varying degrees of thermal stress were tested. Thermoanalytical characteristics that significantly characterize the thermal-oxidative degradation of the studied material were determined; empirical equations were derived for calculating the temperature and duration of preliminary high-temperature exposure of the material.

Methods. Simultaneous thermal analysis was used to test polymer material specimens, while correlation-­regression analysis and multiple linear regression were used to develop a method for estimating the temperature and duration of high-temperature exposure of the material.

Results. The regularities of thermo-oxidative degradation of the polymer material under study were investigated. It was established that the significant thermoanalytical characteristics (criteria) for assessing the temperature-
time exposure to the polymer material under study are the ash residue and the temperature of thermo-oxidative degradation. Empirical equations were obtained that make it possible to calculate the temperature and duration of high-temperature exposure to the laminate during a fire.

Conclusions. A method for assessing the temperature and duration of high-temperature exposure of building finishing materials was developed, enabling the diagnosis of secondary fire sources. Validation of the developed methodological approach and the method for assessing two independent variables demonstrated the reliability of the proposed approach and the validity of the obtained results.

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