Rigid polyurethane foam with improved thermal stability and flame retardancy modified by barium phytate and zinc oxide

Rigid polyurethane foam (RPUF) has been widely used in fields such as construction, furniture, aerospace and so on due to its outstanding properties. However, its flammability seriously endangers people's lives and property safety. Therefore, flame-retardant RPUF has attracted much attention in recent years. Barium phytate (PABA) has good compatibility with polymers and a high phosphorus content, showing good prospects in the field of flame retardancy. In the current study, PABA and zinc oxide (ZnO) were compounded to modify the RPUF. The thermal stability, flame retardancy, smoke suppression and mechanical properties of the modified RPUF was thoroughly analyzed by using thermogravimetric analysis, limiting oxygen index (LOI) test, cone calorimeter (CONE) test, smoke density test and compression performance study. It was shown that the modified RPUF exhibited optimal thermal stability and physical structure properties when the total mass fraction was 15% and the ratio of PABA to ZnO was 2:1 (RPUF-PABA10/ZnO5). Notably, its apparent activation energy (E), integrated programmed pyrolysis temperature (IPDT), initial pyrolysis temperature, and carbon residual rate all reached the highest level. At the same time, the material maintains good physical structure properties. In addition, RPUF-PABA10/ZnO5 exhibited excellent flame retardant and smoke suppression properties. Its peak heat release rate (PHRR), total heat release rate (THR) and total smoke production (TSP) were reduced by 17.95%, 24.10% and 14.38% respectively compared with those of 15% mass fraction of modified RPUF (RPUF-PABA15).