A flammability study of aluminium hydroxide (ATH) and ammonium polyphosphate (APP) used with hemp/epoxy composites

Abstract A detailed flammability study of aluminium hydroxide and ammonium polyphosphate used with natural fibre composites manufactured using a resin transfer moulding process was completed. Three concentrations of each retardant (weight fractions of 4.5, 9, and 13.5%) were used in the study. In characterising the composites, thermogravimetric analysis showed the pyrolysis reactions, which then led to ignition. Using a cone calorimeter and radiant heat fluxes of 20, 35, 50, 75 kW/m2, ignition time and burning rate were studied. Thermal properties measured using the transient plane source method, complemented the ignition study. This work showed the relationship between increasing retardant concentration and flammability.