Nickel Metal-Organic Framework Derived Hierarchically Mesoporous Nickel Phosphate toward Smoke Suppression and Mechanical Enhancement of Intumescent Flame Retardant Wood Fiber/Poly(lactic acid) Composites

Over the past decade, the use of metal-organic framework derived materials has emerged as a novel direction to prepare high performance polymer composites. In this work, nickel based metal-organic framework (Ni-MOF) was synthesized via a cost-effective and environmentally acceptable approach. Ni-MOF derived hierarchically mesoporous nickel phosphate was prepared via a facile hydrothermal method. Morphological evolution from Ni-MOF to nickel phosphate during the synthesis was clearly revealed. The microsized rod-like nickel phosphate was evaluated in both smoke suppression and mechanical enhancement of intumescent flame retardant wood fiber/poly(lactic acid) system. The cone calorimeter test showed a 43% reduction in total smoke production when 5 wt % ammonium polyphosphate was substituted by nickel phosphate. More importantly, both tensile and impact strength of the composites were improved with the addition of nickel phosphate. The as-synthesized nickel phosphate proved to be a promising substitution for ammonium polyphosphate in wood fiber/poly(lactic acid) composites.