Research Of Polyurethane-imide Foam Gradient Flameretarded By Inorganic Flame Retardants

Rigid polyurethane-imide foams flame retarded by inorganic flame retardants,such as ammonium polyphosphate and expandable graphite,were prepared with the inorganic flame retardants and the effects of inorganic flame retardants on the cell structure,density,mechanical properties and flame retardancy of foams were studied.Finally,the synergistic flame retardant mechanism and the gradient mechanism of every inorganic flame retardant was discussed.Cell structures and properties of rigid polyurethane-imide foams flame retarded by one component inorganic retardants were analyzed in this section.The results show that cell diameter of foams,from 699.55 ?m to 360.36 ?m,and the impact strength decrease,while the density of foams and compressive strength,reaching to 0.32585 MPa,increase with the increasing addition of inorganic flame retardants.The cell structure,mechanical properties,flame retardancy and carbon layer morphology were detected.The results show that synergistic flame retardant mechanism obviously exists among the inorganic flame retardants,for the limited oxygen index of foams increases greatly when APP and EG are used together and the smoke density rank of foams decreases sharply and the carbon layer becomes more dense when APP is added into with Kaolin or ZB.ZB can greatly reduce the smoke density rank of foams flame retarded by APP,which drops to 16.7%.What's more,there exist some obvious effects of inorganic flame retardants on the quality change and heat change in the various stages of decomposition of rigid polyurethane-imide foams.