Properties of flame-retardant leaf fiber cement-based composites at high temperatures

Flame retardant modification of leaf fibers was carried out to solve the technical problem of poor fire resistance of plant fibers and improve the utilization rate of urban fallen leaves in building materials. The modification scheme adopts three flame retardants, i.e., ammonium polyphosphate (APP), magnesium hydroxide (MH), and aluminum hydroxide (ATH), and two covering layers, i.e., pure acrylic polymer lotion and water glass (Na₂O · nSiO₂) solution. The modified leaf fiber's combustion behavior and pyrolysis properties were tested and analyzed. The physical and mechanical characteristics, as well as the thermal insulation qualities, of leaf fiber cement-based composites (LFCC) were studied at high temperatures. The findings revealed that the three flame retardants had an effect on the chemical structure of leaf fibers. In comparison to leaf fibers without flame-retardant modification, flame-retardant-modified leaf fibers have a much greater thermal stability. and its LOI is greater than 27.0%, which is a fire-retardant material. Except for the sample with water glass as the modified cover layer, at high temperatures, the composite flame-retardant fiber LFCC's mass-loss rate is lower compared with fibers without flame-retardant modification or fibers modified with only one kind of flame-retardant. In the composite flame-retardant modified fiber LFCC, the samples with better strength at high temperature are those with ATH replacing 30% and 50% MH. The thermal conductivity of LFCC is negatively correlated with the range of temperature change.