/UV Synergistic Aging of Polyester Polyurethane Film Modified by Composite UV Absorber
Figure 3
SEM micrograph of the film surface: (a) unexposed TPU film; (b) TPU film after 400 h of UV/O3 exposure; (c) unexposed M-TPU film; (d) M-TPU film after 400 h of UV/O3 exposure.
