Novel Phosphorous-nitrogen Containing Flame Retardant Polymer Materials: Synthesis, Characterization, And Thermal Properties

With the widespread use of high polymer material, potential risk of fire is risingincreasingly. So study and application of the novel polymer material with high thermostabilityand good fire resistance have aroused material scientists’ concern. N-P synergetic fireretardant has the characteristic features both of phosphorus-containing and ofnitrogen-containing fire retardant. Generally, it shows some advantages such as efficient, lowsmoke, low toxicity, environment-friendly and so on. Based on this, it is aimed to synthetizethree series of phosphrous-nitrogen containing synergetic fire retardant, and to characterizethe structures and properties.In this project work, simple methods of synthesis of DHPZ, HPZ and DOPO-PhOH werestudied, and recrystallization of DOPO-PhOH was optimized. Efficient synthetic route ofpoly（aryl ether ketone）s was explored: water-carrying agent was toluene, solvent was NMP,K₂CO₃beyond50%, concentration of reactants ranged from15%to20%. Two series ofhigh-molecular-weight poly（aryl ether ketone）s with phosphorus and nitrogen on the side andmain chains were synthesized by a nucleophilic substitution polycondensation（DHPZ/DOPO-PhOH/DFBP and HPZ/DOPO-PhOH/DFBP）, and a series of nitrogencontaining polyphosphate esters （HPZ/BPA/PDCP）, their chemical structures werecharacterized by FTIR and nuclear magnetic resonance spectroscopy (¹H NMR,³¹P NMR).The polymers showed excellent solubility in common organic solvents such as NMP,DMAc, DMSO and CHCl₃. The excellent solubility makes the polymer potential candidatefor practical applications in casting processes. Transparent and flexible films were easilyprepared from polymer through casting from CHCl3solutions. The polyphosphate estersobtained were all soluble well in polar solvents, and could formed films easily. Viscosity testand GPC detection indicated two series of PAEKs both viscosity and molecular weight werevery high. Viscosity test indicated the viscosity and the molecular weight of polyphosphateesters obtained were quite high. DSC analysis proved an amorphous morphology and the glass transition temperatures of two series of PEAKs were recorded at163-198oC（DHPZ/DOPO-PhOH） and185-226oC （HPZ/DOPO-PhOH）, respectively.The thermal stability and degradation behavior of the synthesized PAEKs were measuredwith thermal gravimetric analysis （TGA） measurements. An obvious increase of thermalstability was observed with the increase of DHPZ or HPZ degree under N₂atmosphere. In air,the DHPZ or HPZ moieties contributed to retarding oxidation degradation at lowertemperature （<600oC）, while DOPO-PhOH moieties acted that at relative higher temperature（>600oC）. While polymer4b （DHPZ/DOPO-PhOH=3/7） shows the best thermal stability,indicating a good synergic effect between P and N elements and enhancing the thermalstability of the polymer. The TGA data inda indicated the polyphosphate esters （HPZ/BPA）showed good thermal stability. The introduction of nitrogen plays an important role inimprovement the thermal stability of polyphosphate esters.Nitrogen plays a part in insulating thermal and inhibiting smoke and decrease thedegradation rate of the polymers. Meanwhile, phosphorus promotes bviously carbonizationand displays good retardant effectiveness in both condensed phases and gas phase. Nitrogenand phosphorus have a good synergistic effect in the polymer, which impove thermal stabilityand char yield efficiently. So the obtained polymers can serve as flame retardant agent in highpolymer material.