Fire decomposition effects on sandwich composite materials

An experimental study was performed to quantify the microscopic changes in composite construction materials to better understand the thermal and structural behavior of sandwich composites during fire. Real-time videos of microscopic response of resin, composite laminates, and balsa wood from an ESEM were used to understand changes in material morphology at elevated temperature. During decomposition of the resin, microscopic pores developed at 180–200 °C which is the same temperature range where facesheet debond has been observed in fire tests. This indicates that these pores may serve as crack initiation sites in the debond process. Microscopic changes in materials were linked with the trends in permeability and porosity measured at different levels of decomposition.