Functionalized molybdenum tailings improve flame retardancy and mechanical properties of DOPO@chitosan-vanillin Schiff-containing rigid polyurethane foam

To overcome the contradiction between flame retardancy and mechanical properties of rigid polyurethane foams (RPUFs), a reaction-type Schiff base DOPO@chitosan-vanillin Schiff polymer (DOPO@CS-V) is synthesized from chitosan (CS), vanillin, and DOPO. DOPO@CS-V is linked with RPUFs matrix while KH-550 functionalized molybdenum tailings (MTs) and dimethyl methyl phosphate (DMMP) are mixed into RPUFs. The results show that appropriate DOPO@CS-V (4 wt%) and MTs (6 wt%) enhanced the flame retardancy, the p-HRR decreased from 237.5 kW center dot m(-2) to 92.1 kW center dot m(-2), and passed the V-0 rating in the vertical burning test (UL 94). In addition, appropriate MTs increased the compressive strength from 0.15 MPa to 0.25 MPa. This work promotes the application of biomass materials and solid waste in high-performance buildings and industrial materials.