Pyrolysls of a fire-retardant coating consisting of polyurethane and chlorinated alkane

The pyrolysis of a clear fire-retardant coating was studied by using several analytical techniques, such as flash pyrolysis, thermogravimetry (TGA) and differential scanning calorimetry (DSC). The gaseous products were identified using gas chromatography-mass spectrometry (GC-MS). The coating consisted of a polyurethane film with or without chlorinated alkanes, which, when exposed to a flame, produced intumescence. The main ingredients of the coating were tenth-second butyrate and hexamethylene diisocyanate (Desmodur N) for polytrethane and Chlorowax 70 as the fire-retarding component. Pyrolysis was carried out in an inert medium. The pyrograms for polyurethane, Chlarowax and Chlorowax-polyurethane mixtures were obtained at 400, 600 and 800dgC. Some principal gaseous products resulting from the pyrolysis were identified by GC-MS. Other experiments were conducted using DSC under argon, and TGA with temperature programming. The pyrolysis began at 260°C for the Chlorowax-polyurethane system and at higher temperatures for polyurethane. Pyrolysis was also conducted using TGA under isothermal conditions and at selected temperatures.