Study On Synthesis Of Phenolic Aldehyde-Polyurethane Composite Rigid Foams And Their Flame Retardant Properties

Rigid polyurethane (PU) foams have good toughness and heat insulating properties, however, the poor flame retardant properties limit their application in the field of building thermal insulation. Phenolic aldehyde foams have better flame retardant properties, but the brittleness and processability are worse. We got composite foams from polyurethane and phenolic aldehyde foam through copolymerization reaction, the results showed that the composite foams have better flame retardant property, heat insulating property and better processability.In this paper, the synthesis processes of the composite foams were introduced.We synthetized the phenolic resin polyols, phenolic resin polyether polyols, the modified phenolic resin polyols and the modified phenolic resin polyether polyols. The synthesis craft in detail and the index test and characterization of the synthetized polylol were also discussed. By the combinations of appropriate formulas, we synthetized the phenolic aldehyde-polyur ethane composite rigid foams with excellent flame retardant property. Then, the flame retardant properties, the bubble surface morphology and the cellular structure of the composite rigid foams were characterized.In this paper, oxygen index and smoke density were used as the most important test standards of the flame retardant property. We found that the oxygen index of the composite foam can reach above 36%, and the smoke density was reduced to less than 15%. The results conform to the national standard A2 in building materials, and the market prospect of the composite foam is broad.By analysis of scanning electronic microscope (SEM), we concluded that the burning surface of the dense layer of the composite foams can effectively inhibit the spread of combustion, thereby the flame retardant property was enhanced.