A novel polymeric intumescent flame retardant: Synthesis, thermal degradation mechanism and application in ABS copolymer

A novel polymeric intumescent flame retardant containing phosphorous-nitrogen (PSPTR) was synthesized and characterized by FTIR, 1H NMR and 31P NMR. Moreover, a new intumescent flame retardant (IFR) system, which was composed of PSPTR and Phenol Formaldehyde Resin (PF), was used to impart flame retardancy for ABS. Flammability properties of ABS/IFR composites were investigated by Limiting Oxygen Index (LOI) and vertical burning test (UL-94), respectively. The results showed that when the total addition content was 30 wt%, the weight ratio of PSPTR to PF is 1:1, the LOI value of ABS/IFR reached 28.2, and UL-94 reached V-1 rating. A distinct synergistic flame retardant effect exists between PSPTR and PF. The TGA data showed that the IFR (PSPTR/PF = 1:1, wt%) had three weight-loss stages and had a high residue of 50.21 wt% at 700 °C. The thermal degradation process of PSPTR and char-forming mechanism of IFR was studied by thermogravimetric analysis/infrared spectrometry (TG-IR) detailedly.