Combustion behavior and thermal pyrolysis kinetics of flame-retardant epoxy composites based on organic-inorganic intumescent flame retardant

A novel organic-inorganic intumescent flame retardant, expandable graphite modified with charring agent (EGM), was synthesized using expandable graphite (EG), phosphorus oxychloride, and pentaerythritol. Then, EGM was used as flame retardant for epoxy resin. And the flame-retardant properties of epoxy composites were investigated by cone calorimeter test (CCT). The thermal degradation behaviors of epoxy composites were studied by thermogravimetric analysis (TG) in nitrogen atmosphere. And the pyrolysis kinetics of the composites was investigated using Kissinger and Flynn-Wall-Ozawa methods. The CCT result indicated that EGM can reduce the heat release rate and smoke production rate more than EG in flame-retardant epoxy composites: a more compact char residue formed on the surface of the sample with EGM than that of the sample with EG during the combustion process. The TG result showed that the sample with EGM has higher thermal stability than the sample with EG. And the data calculated from Kissinger and Flynn-Wall-Ozawa methods showed that both EP-0 and EP-3 had two thermal degradation stages; EGM can improve the E (a) value of epoxy resins.