Development of photostable bamboo fiber composites: Coupled protection by benzotriazole and hindered amine

The construction of highly photostable outdoor bamboo fiber composites and the elucidation of their protective and degradation mechanisms were investigated in this study. Light-resistant acrylic coatings (LRACs) were prepared by incorporating benzotriazole (BTZ-1) and hindered amine light stabilizers (HALS) into acrylic coatings (ACs). LRACs were subsequently applied to outdoor bamboo fiber composites to prepare photostable composites. After 250 h of xenon arc accelerated aging, the surface stability of the composites was systematically assessed based on adhesion, contact angle, color variation, gloss variation, surface roughness, and surface morphological changes revealed by scanning electron microscopy. Complementary chemical characterizations using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectroscopy (EDS) elemental mapping further revealed the coupled protective mechanisms of BTZ-1 and HALS during the photodegradation of the acrylic matrix. The results demonstrated that the excited-state intramolecular proton transfer (ESIPT) effect of BTZ-1, in combination with the radical scavenging action of HALS, generated a coupled effect that effectively suppressed the degradation rate and significantly enhanced the photostability of the bamboo fiber composites.