Improved thermal stability and flame‐retardant performance of rigid polyurethane foam modified by hydrolyzed keratin‐modified polyol and aluminium hypophosphite

Abstract Rigid polyurethane foam (RPUF) was prepared using hydrolyzed keratin‐modified polyol and aluminium hypophosphite as flame retardants. The effects of aluminium hypophosphite on the thermal stability and flame‐retardant properties of hydrolyzed keratin‐modified RPUFs were studied by limiting oxygen index (LOI) method, thermogravimetric analysis, pyrolysis kinetic analysis, cone analysis and smoke density analysis. The results showed that RPUF added with 7.5 wt% aluminium hypophosphite (RPUF‐HK5‐7.5AL) had the highest LOI, which was 26.1%. RPUF‐HK5‐7.5AL had the highest initial decomposition temperature, the highest T 5% at a heating rate of 10 °C min −1 and the highest activation energy. In addition, RPUF‐HK5‐7.5AL possessed the lowest heat release rate at 50 kW m −2 of 125.10 kW m −2 , and the lowest total heat release rate of 5.30 MJ m −2 . Results indicated that RPUF‐HK5‐7.5AL had the best thermal stability and flame‐retardant properties. Scanning electron microscopy showed that hydrolyzed keratin and aluminium hypophosphite had a synergistic effect on the flame retardancy of the RPUFs. The current research results provide a useful reference for the preparation of RPUFs with good flame‐retardant properties by bio‐based modification. © 2024 Society of Industrial Chemistry.