Preparation and Flame Retardancy of Intumescent/MH Flame-retardant Epoxy Resins

The flame retarding and mechanical properties of new flame retardant composites(FR/APP/MH/EP)were studied using limited oxygen index(LOI)measurement,UL-94 and cone test.The new flame retardant composites were prepared by adding nano-magnesium hydroxide(MH)into six-(4-of DOPO hydroxymethyl phenoxy)cyclotriphosphazene(FR),polyphosphate(APP)and epoxy resin(EP).The results show that when fix the FR/APP 1∶1,adding 1% mass fraction MH,the limited oxygen index(LOI)value of EP2(10%FR/10%APP/1%MH/EP)can reach 36.4%,the peak heat release rate(pk-HRR),average effective heat of combustion(av-EHC),average specific extinction area(av-SEA),average CO release rate(av-CO)of EP2 are reduced by 79.8%,6.73%,47.2%,33.3%,respectively,compared with those of pure EP(EP0)and decrease 20.0%,69.6%,83.6%,58.6%,respectively,compared with those of EP1(10%FR/10%APP/EP),meanwhile,the tensile,bending and impact strengths of EP2 increase 47.6%,75.2% and 196%,separately,compared with those of EP1.SEM observation reveals that EP2 forms a uniform,compact and continuous charred layers after burning,which has good flame retarding,smoke suppression and the toxic effects.