Abstract: The effects of adding ammonium polyphosphate (APP),guanylurea phosphate (GUP) and the mixtures of them on fire retardancy, thermal degradation behavior and mechanical properties of wood flour/high density polyethylene (WF/HDPE) composite were studied using cone calorimetry (CONE), limited oxygen index (LOI), thermogravimetric analysis (TGA) and mechanical test. The results of CONE showed that APP significantly reduced the heat release of WF/HDPE composite, while made the smoke emission increased. When compounding GUP with APP by an appropriate ratio, the composite displayed both low heat release and low smoke release, which indicated a good synergistic effect in fire inhibition and smoke suppression. The results of TGA showed that compounding GUP with APP made the initial thermal decomposition temperature of WF/HDPE composite decreased and improved the char residue. In addition, compounding GUP with APP not only increased the limited oxygen index but also had less negative effects on mechanical properties of the composite.

Key words: wood flour/high density polyethylene(WF/HDPE) composite, ammonium polyphosphate, guanylurea phosphate, fire retardancy