Effect of ammonium polyphosphate on flame retardancy of bio-based rigid polyurethane foams

Rigid polyurethane foam (RPUF) has attracted a lot of attention as a multifunctional material. However, the use of fossil fuels in various fields is limited due to their flammability and excessive consumption in the preparation process. In order to solve this problem, a sustainable bio-based RPUF was prepared by ammonium polyphosphate (APP) and lignin-based polyol flame-retardant modification. The impact of APP on the smoke characteristics, flame retardancy, and thermal behavior of lignin-based polyol RPUFs was examined. The modified RPUF (RPUF-20) with 20 wt.% APP had the greatest starting temperature and residual rate. The maximum activation energy (E) and best thermal stability were found in the pyrolysis kinetics calculation utilizing the thermogravimetric trajectory compared with other specimens. Cone showed that when RPUF-20 was compared with RPUF-0, the peak heat release rate was lowered by 79.43%, 72.79%, and 67.91%, and the total heat release was reduced by 50.59%, 56.29%, and 37.14%, respectively. In addition, RPUF-20 had the lowest smoke density, according to the statistics. The current results showed that RPUF-20 had low smoke toxicity and outstanding flame retardancy, which gave rise to a novel notion for RPUFs following flame-retardant modification using biomass.