Abstract:

Firstly, sodium lignosulfonate(SLS) was liquefied and modified, and then the SLS liquefied product was used to replace polyether polyols, and the flame retardant ammonium polyphosphates(APP) was added. The liquefied SLS-based flame retardant polyurethane foam(SLS-PUF/APP) was prepared by one-step foaming method. The physical properties of SLS liquefaction products were characterized. The flame retardancy of the materials was studied by limiting oxygen index(LOI) and vertical combustion test. The combustion behavior, microstructure and compression properties of the materials were investigated by cone calorimeter(CONE), scanning electron microscope(SEM) and electronic universal testing machine. The test results showed that the hydroxyl value, residue rate and viscosity of SLS liquefaction products were 537.3 mg/g, 0.77% and 332 mPa·s, respectively. When the SLS liquefaction product substitution rate for polyether polyol was 100%, the LOI value of the prepared material(100%SLS-PUF) reached 20.3%. On this basis, when the APP addition amount was 20%, the LOI value of the prepared material(100%SLS-PUF/20%APP) reached 23.9%. When the APP addition amount was greater than 19%, the vertical combustion grade of the material could reach the Ⅴ-0 level. Compared with pure PUF material, the maximum heat release rate and total heat release amount of 100%SLS-PUF/20%APP decreased by 693.5 kW/m² and 7.7 MJ/m², respectively, and the residual carbon content increased by 14.5 percent. At the same time, its compressive strength increased, from 74.0 kPa of pure PUF material to 283.8 kPa, indicating that the substitution of SLS liquefaction product and the addition of APP could significantly improve the compressive performance of PUF material and its flame retardant performance.

Key words: polyurethane foam, sodium lignosulfonate, liquefaction, ammonium polyphosphate, flame retardancy, compressive strength