Flame-Retarding of Polylactide Fabrics.

Abstract

The flammability and flame-retarding of polylactide fabrics were investigated. The limiting oxygen index (LOI) value of untreated polylactide fabric was 24.1%. This result proved that polylactide fabric is not incombustible, but is difficult to burn continuously in air. Polylactide fabrics were treated with several bromine-containing flame retardants and a phosphorus-containing flame retardant, triphenylphosphate (TPP), respectively, at 120°C in water for 30min. Among the bromine-containing flame retardants used in this study, tetrabromobisphenol A (TBP-A) had the highest efficiency of sorption. However, the LOI value of treated fabric remained at 25.9% when the amount of sorbed TBP-A increased over 4.38% o. w. f. (percent on the weight of the fiber). From the DSC data, it was suggested that the sorption sites which have strong affinities for polylactide segments are occupied by TBP-A molecules up to 4.38% o. w. f. On the other hand, in the case of TPP treatment, the LOI value reached 27.8%, a maximum, at 3.05% o. w. f. When the amount of sorbed TPP increased to 12.78% o. w. f., however, the LOI value decreased to 25.4%. From the scanning electron micrograph and DSC data of the treated fabric containing 12.78% TPP, it was found that an excess amount of sorbed TPP crystallizes on the surfaces of polylactide fibers. The formation of crystalline TPP caused the tensile strength to be depressed to ca. 30% as compared to the untreated fabric. From these results, an important conclusion was made that a high flame retardancy can be given to polylactide fabric by moderate TPP treatment.