, , , , Elizabeth Knowlton, Benito De Leon
Cone calorimetric experiments have been conducted on bare flexible polyurethane foam (FPUF) samples as well as FPUF covered with a variety of fire-blocking barrier fabrics (BFs) in order to characterize and rank BF effectiveness for improving the flammability characteristics of residential upholstered furniture (RUF). In addition to BF properties, it has been demonstrated that the burning behaviors of the FPUF/BF composites were sensitive to a wide range of experimental parameters including the sample configuration, heat losses to the underlying support base, and the two-stage pyrolysis behavior of the FPUF. Measurements using thermocouples (TCs) placed within the FPUF provided insights on FPUF pyrolysis behavior, the collapse rate of FPUF, and the thermal protective properties of barrier materials. The majority of HRR curves for the FPUF/BF composites showed evidence for three-stage burning associated with initial flash burning of the BF followed by the two-stage burning of the FPUF. The presence of a BF was shown to reduce the HRR peak values during both FPUF burning stages. The magnitude of the peak associated with second-stage FPUF burning (denoted PHRR2) was deemed the most appropriate for characterizing the thermal protection provided by a BF. Since the times for PHRR2 also varied between composites, a measure referred to as the peak fire growth rate (PFIGRA) parameter was also considered. Three possible classification schemes, each consisting of three classes, were introduced based on composite flame extinction and reignition behavior, PHRR2 values, and PFIGRA2 values. Each classification scheme provided differentiation between BF effectiveness. While the schemes agreed well regarding particularly effective or ineffective BFs, there were variations among classes for BFs having intermediate levels of effectiveness. Further work will be required to assess which, if any, of the classification schemes are useful for predicting BF performance in RUF.
Technical Note (NIST TN) - 2043
Fire-blocking barrier fabrics, flexible polyurethane foam, cone calorimetry, heat release rates, temperature measurements