The Iodometric Determination of P(III) in Flame Retardants for Cotton

Abstract

Three iodometric methods have been investigated for the determination of P(III) in cotton fabrics finished with THPOH/ammonia resins. The iodine method developed previously for Thpc/amide resins gives P(III) values that are much too high. The iodate method gives P(III) values that are too low or too high, depending on whether the cotton substrate is present or absent during the titration of the excess iodate. The preferred method is the peroxide method, which gives P(III) values that do not, within the limits of experimental error, vary with time or disposition of the cotton substrate. When applied to Thpc/amide resins, the peroxide method shows good agreement with the iodine method. The behavior of key resin precursors toward these oxidants has also been investigated.