A reinforced thermal barrier coat of a Na–tannic acid complex from the view of thermal kinetics

a two-step reaction, producing a multicellular char of crosslinked aromatic rings, followed by the blowing of carbonaceous cells into a further expanded structure. This intumescent function of tannic acid was found to be enhanced upon its complexation with sodium ions, which greatly increased the activation energy for the first step of the reaction of tannic acid, to promote the formation of a stable char. The resulting blown char coated the cotton fiber below the thermal decomposition temperature of cellulose and was sustained throughout the decomposition. The enhanced thermal barrier performance of the Na-tannic acid complex was demonstrated by the reduced heat release capacity of cotton, the value of which was only about one-third that of tannic acid itself, and the inhibition of flame generation on cotton.