Synthesis And Flame Retardance Of Phosphorus-nitrogen And Phosphorus-Nitrogen-silicon Flame Retadant

Polyurethane(PU)and epoxy(EP)have been widely used in many fields.Due to limiting oxygen index(LOI)is 17～20%,PU and EP are belonged to inflammable materials and required fire retardant treatment in practical.Currently,halogen-containing flame retardant is the leading flame retardant products in the world owing to little additive amount and good flame-retardant efficiency.But a large of fumes and corrosive smoke,especially dioxin,have been released during the combustion process and produced serious polluted and healthy problems.However,there is an urgent demand to develop halogen-free flame retardants for polymer.In this work,three phosphorus-nitrogen containing flame-retardants and two phosphorus-nitrogen-silicon containing flame-retardants were designed and synthesized.Then the flame resistance of EP and PU were explored by choosing four different flame retardants.The main research results are concluded as follows:1.P-H bond containing phosphonates intermediates DDPO and DOPO were synthesized by the reaction of neopentyl glycol and o-phenylphenollue,respectively.Then five flame retardants containing phosphorus-nitrogen(P-N)and phosphorus-nitrogen-silicon(P-N-Si)(DPPO,HAPO,HPPO,TSBS and DSOA)were synthesized based on the addition reaction of P-H bond and imide group(C=N),respectively.Their chemical structures were characterized by FT-IR,1HNMR,31P NMR and Elemental analysis.The thermal properties were characterized by TGA/DGA analysis.HAPO,HPPO,DPPO and DSOA were selected to flame retardant modified PU and EP according to their thermal performance and synthesis condition.2.Isocyanate PAPI(PM200)and polyether polyol 4110 as raw materials,the impact of foaming agent,cross-linking agent,catalysts and stabilizer were investing on results of the PU foaming technology.The appropriate condition of PU foaming was confirmed.Halogen-free flame-retardant polyurethane foams(PU/DPPO,PU/HAPO,PU/HPPO,PU/DSOA)were prepared using DPPO,HAPO,HPPO and DSOA,respectively.Their structures were characterized by FT-IR and SEM.The flammability was investigated using limiting oxygen index(LOI),a vertical burning test(UL-94),and a cone calorimeter.As a result,after the flame retardant added,flame retardancy and stability of PU increased with increasing content of flame retardant.Through the contrast research between them,it was known that HAPO exhibited better flame retardant and thermal properties than others.When HAPO(15wt%)as flame retardant was added to PU(PU/HAPO/15%),the LOI was increased to 23.8%,and a UL-94 V-0 rating was achieved.The surface morphology and chemical structure of chars were investigated by SEM,the compacted charred layers were observed.The charred layer of PU/DSOA is more compact than others due to the existence of silicone.Meanwhile Cone results demonstrated that the presence of HAPO or DSOA imposed a positive effect on the retardancy of PU.When increasing the concentration of HAPO or DSOA content up to 10%,the peak heat release(PHRR),the total heat release(THR)and total smoke production parameters(TSP)of PU/HAPO/10%and PU/DSOA/10%,were reduced from 391 kW/m2 to 367,346 kW/m2,from 30.9 to 27.1,27.6MJ/m2,from 9.07 to 6.99,5.55 m2/m2,respectively.3.Taking E51 as raw material,ethylenediamine as the curing agent,phenol as accelerant,benzyl alcohol as diluent and silicone oil as stabilize,curing 2 hours at 45℃and 48 hours curing time at room temperature,developed curing technology and EP was prepared successfully.Halogen-free flame-retardant EP(EP/DPPO,EP/HAPO,EP/HPPO and EP/DSOA)were prepared using DPPO,HAPO,HPPO and DSOA,respectively.Their structures were characterized by FT-IR.The results indicated that bonding effect of HPPO with EP better than others,so compatibility and dispersion of HPPO were enhanced in EP material.The flammability was investigated using limiting oxygen index(LOI),a vertical burning test(UL-94).Flame retardancy and anti-dripping of EP were increased with increasing content of flame retardant.Through the contrast research between them,it was known that HPPO exhibited better flame retardant and thermal properties than others.When HPPO(15wt%)as flame retardant was added to EP(EP/HPPO/15%),the LOI was increased to 25.3%,and a UL-94 V-0 rating was achieved.4.The solubility data of DPPO in twelve solvents were obtained at temperature ranging from 278.15K to 347.15K by gravimetrical method.The experimental data were correlated with the modified Apelblat equation and the calculated solubilities by the model were in good agreement with experimental values and provided basic physical data for solvent selection in synthesis and purification of the compound.