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

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 T5% at a heating rate of 10 degrees 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. (c) 2024 Society of Industrial Chemistry. Fabrication, improved thermal stability and flame-retardant performance of rigid polyurethane foam modified by hydrolyzed keratin-modified polyol and aluminium hypophosphite. image