Synthesis Of Two Kinds Of Triazine-based Flame Retardants And Applied Researches On Flame Retardancy Of Polypropylene

Polypropylene (PP) is widely applied in various fields like construction, household and packagedue to overwhelming advantages such as non-toxicity, high transparency and excellent electricinsulation, etc. But its application is limited on account of its inflammability. In this paper, a novelintumescent flame retardant (nIFR) and phosphorus–nitrogen containing intumescent flame retardant(PSCP) were synthesized and investigated as an environmental friendly flame retardant for PP.(1) A derivative of triazines (PTPA) was synthesized and its chemical structure was characterizedby nuclear magnetic resonance spectrometry (1H-NMR), Fourier transform infrared spectrometry(FT-IR) and element analysis (EA). Thermogravimetric Analysis was used to investigate the thermalstability of the novel intumescent flame retardant (nIFR) which contains different ratio of ammoniumpolyphosphate(APP) and PTPA. TGA results showed that PTPA has excellent thermal stability, itsinitial degradation temperature is464℃, and the residue of PTPA at800℃is52.35%in N2atmosphere. Novel intumescent flame retardant (nIFR) was added into PP via melt blending. Theflammability and thermal degradation properties of PP/nIFR composites were characterized bylimiting oxygen index (LOI), UL-94measurements, Cone calorimeter test (CCT) and TGA. It wasfound that the flame retardancy of PP/nIFR composites could pass V-0rating in UL-94tests, andpossessed a LOI value of32%when only20%nIFR was loaded in PP (PP/nIFR20). CCT resultsshowed that the total heat release (THR) of PP/nIFR20is74MJ/m2, the peak heat release rate is163kW/m2, the total smoke release(TSR) and smoke release rate are7.31m2/kg and0.031m2/s,respectively. In addition, the degradation activation energy of PP/nIFR20was studied by Kissingermethod. It was found that the degradation activation energy of PP/nIFR20is183.7kJ/mol, which wasmuch higher than that of PP and PP/IFR30, with the value of82.4kJ/mol and135.3kJ/mol, repectively.SEM was used to study the microstructure of char residues, it was found that the the char residue ofPP/nIFR20is much more compact and firm than that of PP/IFR30.(2) Based on the molecular design, a kind of phosphorus–nitrogen containing intumescent flameretardant (PSCP) whose ratio of N and P are1.6:1,2:1,3:1,4:1were synthesized and wellcharacterized by FT-IR and1H NMR. Thermogravimetric analysis (TGA) was performed toinvestigate the thermal stability of PSCP. The results showed that PSCP presented high thermalstability, and the largest char residue amount62.7wt%at800℃in N2atmosphere was obtainedwhen the N/P molar ratio is2:1. The intumescent flame retardant PP/PSCP composites were prepared via two screw extruder. The flammability and thermal stability of PP/PSCP20composites wereinvestigated through LOI, UL-94tests, TGA and Cone calorimeter test (CCT). It was found thatPP/PSCP20could achieve V-0rating in UL-94tests and LOI could reach27%, CCT results showedthat the total heat release (THR) of PP/PSCP20is85MJ/m2, the heat release peak is262kW/m2, thetotal smoke release (TSR) and smoke release rate are6.67m2/kg and0.035m2/s respectively. Furthermore, the degradation activation energy of PP/PSCP20was investigated by Kissinger equation. Theresult showed that the degradation activation energy of PP/PSCP20is166.3kJ/mol, which was muchhigher than82.4kJ/mol of PP, it indicated that PSCP can impove the therm-stability of PP/PSCPcomposites.