Melamine-based polyol containing phosphonate and alkynyl groups and its application in rigid polyurethane foam

The rapid depletion of energy resources is the most serious challenge facing humanity today. Energy consumption by buildings is the largest component of energy consumption, and most of it is in the form of heat loss. Therefore, many buildings use rigid polyurethane foam (PUF) as thermal insulation material to effectively reduce heat loss. However, the greatest disadvantage of PUF is its high flammability. In this work, to reduce the risk of fire caused by PUF, melamine-based polyol containing phosphonate and alkynyl groups (MF3.5 and MB3F3) is synthesized and used to improve the flame retardancy of PUF by replacing common polyether polyol. The effects of MF3.5 and MB3F3 on the physical and mechanical properties, cell morphology, thermal stability and flame retardancy of PUF are systematically studied. The research results show that the flame-retardant polyols have no effect on the thermal insulation properties of PUF, but result in a slight decrease in compressive strength. Thermogravimetric analysis proves that MF3.5 and MB3F3 can increase the temperature of the maximum mass loss rate and reduce the maximum mass loss rate, and significantly increase the char yield at 800 °C. The limiting oxygen index (LOI) value is increased to 24.3%. Cone calorimetry experiments show that MB3F3 reduces the peak heat release rate and total heat release by 28.2% and 30.5%, respectively. Vertical combustion tests show that the average burning rate of the flame-retardant PUF is much slower, and melt-dripping behavior is eliminated. The flame retardancy of PUF is improved mainly through a condensed phase mechanism.