Thermal stability of UV irradiation crosslinked polylactic acid fibers and fabrics

The poor thermal stability of polylactic acid (PLA) fibers and textiles severely restricts their application in high-temperature environments. In this research, an ultraviolet (UV) irradiation method was proposed to prepare the crosslinked PLA fibers and fabrics, where the composite photoinitiator was added during the spinning process. The effects of UV irradiation time and environmental conditions on the fiber gel content, mechanical property, crystallization, and thermal stability were fully investigated. The results demonstrate that UV irradiation-induced crosslinking under ambient air condition yields a gel content of 57% in the fibers, whereas the irradiation in vacuum notably enhanced the value to 85.5%, confirming the inhibitory effect of oxygen on the UV-initiated crosslinking process. Concurrently, the highly crosslinked gel network structure endows the PLA fibers with exceptional dimensional stability, which is evidenced by the reduction of thermal shrinkage from 20–45% (precrosslinking) to below 3%, accompanying a significant elevation in thermal fracture temperature from 67 to 93°C. Furthermore, these fibers were used to fabricate the PLA fabrics and present exceptional dimensional stability compared with the uncrosslinked fabrics, establishing a theoretical foundation for developing high-temperature-resistant PLA textiles. This research is significant for accelerating the PLA application in textile and clothing.