Synergistic Flame Resistant Effect of Zinc Oxide and Intumescent Flame Retardant in Polypropylene

A new type of intumescent flame retardant(IFR) has been synthesized using phosphorus acid,pentaerythritol and melamine.Intumescent flame retardant PP composites have been prepared based on PP as matrix resin,intumescent flame retardant as flame retardants and zinc oxide(ZnO) as synergism.The synergist effect between ZnO and IFR has been studied using limiting oxygen index test,UL-94 test and cone calorimeter.The changes of solid-phase structure in the thermal degradation process have been studied by dynamic FTIR spectroscopy.The results showed that the synergist effect obviously did exist between ZnO and a new IFR;the structures of the composites changed severely from 240 ℃ to 330 ℃;when the sample containing 1.6% ZnO,the char morphology got the best integrity among all samples,and the peak heat release rate was also the lowest,decreased 80% than PP without flame retardant,the UL-94 of this sample was V-0;when the content of ZnO increased to 3.2%,LOI value got to 25.6%,and the UL-94 passed V-0.