Novel organic-inorganic hybrid polyphosphazene modified manganese hypophosphite shuttles towards the fire retardance and anti-dripping of PET

A novel organic-inorganic hybrid polyphosphazene modified manganese hypophosphite (PZS-MnHP) shuttles was facilely fabricated and applied in enhancing the flame retardance and anti-dripping behavior of PET. The PET containing 5 wt% PZS-MnHP shuttles (PET/FR5.0) possessed a LOI value of 25.3% and corresponding melt-dripping was greatly restricted with few droplets. Incorporating 5 wt% PZS-MnHP shuttles also brought about dramatic decrease in the fire hazard of PET, for instance, 57.0% maximum reduction in heat release rate. Moreover, the tensile strength of PET/FR5.0 composite was gradually increased from 50.87 MPa to 55.68 MPa, relevant elongation at break was enhanced by 7.2% compared with that of PET. The flame-retardation mechanism of PZS-MnHP shuttles in PET was also systematically investigated. The results showed PZS-MnHP shuttles extremely accelerated the formation of intumescent char, cutting off the supply of external oxygen and heat. Moreover, inflammable gases including SO2 and NH3 released from PZS-MnHP shuttles efficiently diluted combustible organic volatiles in burning area, further blocking the spread of fire.