Novel phosphorous-nitrogen intumescent flame retardant system. Its effects on flame retardancy and thermal properties of polypropylene

摘要

This paper describes the effectiveness of novel phosphorous-nitrogen intumescent flame retardant system (ammonium polyphosphate 202 and PPM Triazine HF - trademark, abbrev. IS) on fire retardancy and thermal stability properties of polypropylene (abbrev. PP) at incorporation level below the standard amount required for intumescent flame retardant system. UL-94 vertical burning test revealed that the addition of 20 wt.% of IS into neat PP is enough to reach V-0 rating (short burn without dripping). Further, a higher increase of the oxygen concentration for ignition was also found with the addition of the novel intumescent flame retardant to neat PP; LOI value of neat PP by addition of 20 wt.% IS rose from 19 to 31 vol.%. Finally, a remarkable decrease of peak heat release rate (PHRR: -91%), total heat release (THR: -42%), average of mass loss rate (AMLR: -92%), average of specific extinction aria (ASEA: -48%) and total smoke release (TSR: -58%) was revealed with increasing in IS content. Novel intumescent flame retardant system showed good flame retardancy performance pointing out that the intumescent char formed resists oxidation; this aspect was also confirmed by the thermog-ravimetry analysis. Hence, it can be pointed out that the improvement of flame retardancy imparted by the novel intumescent flame retardant system at lower concentration enables on one side a lower cost material formulation and on the other side the impact on the mechanical properties of the polymer might be lower. The thermo-oxidative data have revealed an enhancement of the thermal stability of the PP matrix by incorporation of IS (the PP/20IS composite showed a markedly increase in T_(onset): 14℃ and T_(max): 64℃).