Abstract:

The liquefied sodium lignosulfonate(SLS) products were used to completely replace polyether polyols, the intumescent flame retardant(IFR) was composed of chitosan(CS) and ammonium polyphosphate(APP), and montmorillonite(MMT) were used as additives, which were employed to prepare MMT/IFR intumescent flame retardant/liquefied lignosulfonate based polyurethane foam(SLS-PUF/IFR/MMT). The flame retardancy, thermal stability, combustion performance, thermal conductivity and compression properties of the materials were analyzed by scanning electron microscope(SEM), limiting oxygen index(LOI), thermal gravimetric(TG) analyzer cone calorimeter, thermal conductivity tester and electronic universal testing machine. The results showed that: when the addition amount of IFR was 20%, the LOI value of the prepared material 100%SLS-PUF/20%IFR reached the highest value of 24.3%. When the amount of IFR was ≥16%, the vertical combustion grade of the prepared material 100%SLS-PUF/IFR reached Ⅴ-0 level. Basis on this result, the LOI value of the prepared material 100%SLS-PUF/20%IFR/2%MMT reached 24.8% and its vertical combustion grade could reach Ⅴ-0 level, when the addition of MMT was 2%. Compared with 100%SLS-PUF material, the rate of thermal degradation of 100%SLS-PUF/20%IFR/2%MMT material decreased by 0.6%/min, and its maximum heat release rate and total heat release were 145.6 kW/m² and 13.9 MJ/m², respectively. Moreover, the carbon residue content increased by 13.1 percentage points. At the same time, its apparent density and compressive strength were significantly increased to 58.72 kg/m³ and 296.6 kPa and its thermal conductivity also reached 0.041 W/(m·K).

Key words: polyurethane foam, sodium lignosulfonate, flame retardant properties, compressive strength