Flame Retardant Mechanism Of Phosphorus Flame Retardant Rigid Polyurethane Foam

Phosphorus flame retardants play an important role in the research of the flame retardancy in polyurethane.Exploring the flame retarded mechanism and improving the efficiency of flame reta retardancy have been become one of the focus in this field.In this work,firstly,the phospho-containing polyol(DMMP-EG)was prepared by transesterification reaction between dimethyl phosphonate(DMMP)and glycol.And the modified graphite(MEG)was prepared by grafting expanded graphite with phosphorsilane coupling agent.Then,the flame retardancy,mechanical properties and thermal stabilities of flame retardant RPUF by DMMP-EG,MEG and ammonium polyphosphate(APP)were studied.In DMMP-EG/RPUF,the overall performance of the foam is optimal when DMMP-EG is 10-20 parts.Therefore,based on 15 percent DMMP-EG,APP and MEG were loaded to flame retardant RPUF.In DMMP-EG/APP/RPUF,when the additive amount of APP was 30 percent,the best comprehensive performance was reached-compression strength was 1.25% higher and the impact strength was 101.53% higher than pure RPUF respectively,and LOI was 22%.In DMMP-EG/MEG/RPUF,with the addition of 75 percent MEG,the overall performance was the best,LOI was 29.4%.Compared with pure RPUF,the compression strength and impact strength decreased by 2.95% and 12.94%,respectively.In DMMP-EG/APP/MEG/RPUF,fixed the totel content 30 percent of APP and MEG,when APP/MEG was1/1,LOI was 24% and the lowest value of SDR was 29.Compared with pure RPUF,the compression strength was increased by 51.3% and the impact strength was reduced by 32.94%.Forthemore,the mechanisms of flame retardancy were discussed through TGA,CONE and SEM-EDS.The results show that the flame retardancy of DMMP-EG displays gasphase and condensed phase affect,the flame retardancy of DMMP-EG/APP presents mainly condensed phase affect and the flame retardancy of DMMP-EG/MEG was both gas-phase and condensed phase affect.In DMMP-EG/APP/MEG,the flame retardancy mechanism is mainly condensed phase affect which depends on the proportion of APP.Figure 56;Table18;Reference 74.