Thermal degradation and flame retardancy of nylon 6/aluminum methylmethoxy phosphonate composites.

An aluminum methylmethoxyphosphonate (AlPo)-based flame retardant (FR) was synthesized. Thermal degradation and flame retardancy of nylon 6 (PA6)/AlPo composites were examined and compared with PA6/commercial aluminum diethylphosphinate (AlPi) composites. The PA6/AlPo composite achieved a V-0 rating at 20 wt% loading during the UL-94 test, and it exhibited the formation of a charred layer that protected the polymer from burning and reduced the release of gases during the combustion of PA6. AlPo demonstrated exceptional performance in gaseous and condensed phases in the PA6 matrix, whereas AlPi only worked in the gaseous phase. The differences between the thermal degradation mechanisms and flame retardancies of AlPi and AlPo were investigated via Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and cone calorimetry. A suitable degradation mechanism was proposed to aid the development of flame retardants in the future.

Novel Nitrogen-Phosphorus Flame Retardant Based on Phosphonamidate: Thermal Stability and Flame Retardancy.

A novel nitrogen-phosphorus flame retardant (P-N FR) based on phosphonamidate, dimethyl N,N'-1,3-phenylenebis(P-methylphosphonamidate) (DMPMP), was successfully synthesized and its flame-retarding performances and thermal degradation were compared with those of other P-N FRs and a phosphorus-based FR such as resorcinol bis(diphenyl phosphate) (RDP). DMPMP was applied to acrylonitrile-butadiene-styrene (ABS) and ethylene-vinyl acetate (EVA) to investigate the factors governing the flame-retarding behaviors of P-N FRs which would make them efficient for noncharrable polymers. V-0 ratings were achieved at 20 wt % loading of DMPMP for ABS and at a much lesser amount of DMPMP loading (10 wt %) for EVA. Meanwhile, no rating and V-2 were achieved even at 20-30 wt % loading of other P-N FRs or RDP for ABS and EVA, respectively. The results from thermogravimetric analysis, Fourier transform infrared, and UL-94V indicated that DMPMP is a highly efficient FR and acts mainly in a gas-phase flame-retarding mode of action. The condensed phase of DMPMP also contributed to the flame retardancy property through -NH- groups which tendentiously generate a nitrogen-phosphorus-rich residue because of the intermolecular coupling transesterification reaction. These results demonstrated the assumption that DMPMP has a high P content and good hydrostability, which exhibits good flame retardancy for noncharrable polymers such as ABS and EVA.