Photostabilization of Poly(butylene adipate-co-terephthalate) (PBAT) Films with Hindered Amine Light Stabilizers: Performance Evaluation and Mechanistic Insights

The application of poly(butylene adipate-co-terephthalate) (PBAT) biodegradable plastics has long been constrained by insufficient
light aging resistance. Hindered amine light stabilizers (HALSs), known as eco-friendly additives, can scavenge free radicals to enhance polymer
durability. However, rough choices have resulted in wastage of resources and environmental pressure. Based on the application of plastic films as
the background for use, this study systematically evaluates application effects of five HALSs. The films underwent accelerated aging for various
durations and were further investigated by a combination of experiments and molecular simulation. Results showed that all HALSs mitigated
PBAT light aging, with Chimassorb-944 (UV-944) and Tinuvin-770 (UV-770) performing the best for real applications. Quantum chemical calcula
tion results showed that UV-944 had stronger anti migration ability. After 300 h of aging, films with UV-944 and UV-770 retained superior tensile
strength and elongation at break in the transverse direction compared to neat PBAT films. Polymeric HALSs provided better long-term stability
than small-molecule ones. Further spectra analysis indicated that stronger C―O bonds in HALS/PBAT composites correlated with improved pho
tostability. This study offers valuable insights into improving weather resistance of PBAT biodegradable films and optimizing the real application
of HALSs.