Synthesis and carbonization chemistry of a phosphorous-nitrogen based intumescent flame retardant
writer：Ma HY*, Fang ZP
keywords：intumescent flame retardant，synthesis，carbonization chemistry
source：期刊
specific source：Thermochim Acta, 2012.9, 543: 130-136
Issue time：2012年
The char formation of intumescent flame retardant (IFR) plays a pivotal role for flame retarded polymer systems. In this work we studied the carbonization chemistry and mechanism of a polymeric phosphorous-nitrogen containing intumescent flame retardant named poly (diaminodiphenyl methane spirocyclic pentaerythritol bisphosphonate) (PDSPB). Thermogravimetric analysis (TGA), dynamic fourier transform infrared spectroscopy (in-situ FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) were used to investigate and monitor the thermal behavior and structural changes during its thermal degradation. The thermal stability of PDSPB is higher than most commercial IFRs. As an oligomer, three-step degradation behavior was found for PDSPB. The PDSPB oligomer polycondensed further and generated a higher macromolecular weight one during the initial step. With the increasing of temperature, the phosphate ester bonds in PDSPB were broken down and released phosphoric acid which dehydrated the carbon source to form semi-liquid chars. The blowing agent degraded and emitted non-flammable gases to swell the chars. The residues were further degraded into final chars during the last step. The final chars showed a complex P-O-Ph and aromatic/graphitic structure containing architecture. The graphitization degree was investigated. The three sources (acid source, carbon source and blowing agent) in PDSPB have excellent matching thermal behavior.