Rayon fabrics, untreated or treated with sulfur-containing acids, nitrogen-containing bases and their salts or mixtures, were pyrolysed at 300°C in air, and the yields and the tensile strengths of charred rayon fabrics were measured. For the comparison, the salts of phosphoric acid, hydrochloric acid or nitric acid were also examined as treating agents.
All of the compounds investigated, except ammonium nitrate, act to increase yield of charred fabrics. On the other hand, the compounds remarkably increasing tensile strength of charred fabrics seem to be restricted to the combinations of following acids and bases; Acid: surfuric acid, sulfurous acid, sulfamic acid and thiosulfuric acid Base: ammonia, urea, guanidine triethanolamine and aniline
The results are discussed in relation to the flameproofing mechanisms of cellulose.