Abstract
The oxidative decomposition of polylactide fabrics irradiated with ultraviolet light in an ozone-oxygen atmosphere was investigated. The tensile strength of irradiated yarn remained almost constant up to 70 s of irradiation time, but it decreased steeply in the range of 70 to 300 s and did slowly above 600 s. The elongation discontinuously decreased in the range of 300 to 600 s, because the cold drawing did not occurred in the region of more than 600 s. In the DSC heating curves of irradiated fabrics, the double melting behavior remarkably changed in shape above 150 s and the peak temperatures shifted to the low-temperature side with increasing irradiation time. This result suggested that the melting-recrystallization-remelting behavior had changed since tie molecules had been decomposed. The enthalpy data of melting proved that the crystallites of samples irradiated for more than 600 s had been partially destroyed. When the carboxylic groups were analyzed by absorption of basic dye molecules on the sample surfaces, it was suggested that the oxidative decomposition is retarded on the surface of polylactide fiber.
