Synthesis and characterization of flame-retardant rigid polyurethane foams derived from gutter oil biodiesel

[Display omitted] •Gutter oil biodiesel-based polyol and diethyl bis(2-hydroxyethyl)- aminomethylphosphonate were successfully synthesized, respectively.•Gutter oil biodiesel-based flame-retardant rigid polyurethane foams were successfully fabricated via employing cost-efficient aluminum hydroxide and easily prepared diethyl bis(2-hydroxyethyl)- aminomethylphosphonate.•Gutter oil biodiesel-based flame-retardant rigid polyurethane foams were potential candidates in fire insulation materials for future application in architectures. In this study, gutter oil biodiesel-based polyols (GOBP) and a reactive-type flame retardant named diethyl bis(2-hydroxyethyl)-aminomethylphosphonate (BHAPE) were both synthesized. Subsequently, gutter oil biodiesel-based flame-retardant rigid polyurethane foams (BPUFs) were prepared with GOBP, BHAPE, aluminum hydroxide (an additive-type flame retardant) and polymeric diphenylmethane diisocyanate. The properties of the BPUFs, including density, thermal conductivity, compressive properties, chemical component, morphology, thermal stability, limiting oxygen index, cone calorimetry testing, char residues stability were characterized. Among them, BPUF-AB owning 6.97 wt% of GOBP, 18.59 wt% of BHAPE and 39.77 wt% of aluminum hydroxide obtained a lower density of 0.097 g/cm3, a lower thermal conduction of 0.048 W/(m * k) and the highest compressive strength of 187 ± 13 kPa. Fire testing revealed a highest limiting oxygen index value of 30.1% and passed the UL-94 standard test. Cone calorimetry testing revealed that the peak heat release rate and peak smoke production release of BPUF-AB were reduced by 51.08% and 57.10%, respectively. Meanwhile, the total heat release rate and total smoke production were respectively decreased by 36.88% and 40.79%. The results indicate that BPUFs derived from gutter oil biodiesel are prosperously potential biomaterials with good thermal stability for fire insulation porous materials in future architecture applications.