Abstract:The accelerated aging treatment of polylactic acid (PLA) was carried out by ultraviolet aging tester. The effects of short-cycle UV aging on different surface aging mechanisms of PLA and internal aging, as well as the crystallization time and mechanical properties of PLA were investigated. The results show that with the increases of aging time, the C=O diffraction intensity of the PLA surface becomes smaller continuously, while the C=O diffraction intensity of the PLA inside decreases first, and then increases. Moreover, the surface morphology of PLA surface area where shows a few partial cross-linking is rougher than that of the inside. After aging treatment for 24 h, 48 h and 72 h, the crystallinity (Xc) of PLA surface increases to 19.4%, 32.73% and 35.22%, and Xc of PLA inside increases to 14.98%, 27.52% and 32.63%, respectively. Notly, Xc of the PLA surface is always larger than that of the inside, and this tendency gradually decreases with the increase of aging time. Compared to PLA without aging, the tensile stress, impact strength and elastic modulus of PLA aged for 72 h are increase by 11.49%, 38.38% and 43.2%, respectively.