Tailoring the desired optical and mechanical performance of polyester-plasticized PVC films: the role of different light stabilizers on the photo-degradation

Effect of hindered amine light stabilizer (HALS: C944) and ultraviolet absorbers (UVAs: UV326, UV531) on the photo-stabilities of polyester-plasticized poly(vinyl chloride) (PVC) and polyester-plasticized PVC/pigment yellow (PY) films were studied systematically. Both ultraviolet absorbers (UVAs) and hindered amine light stabilizer (HALS) could slow down the discoloration of polyester-plasticized PVC and polyester-plasticized PVC/PY films. However, the addition of UVAs protected polyester-plasticized PVC films from being discolored and its efficiency is higher than HALS. The specific order of stabilizing effect on the photo-oxidation is UV326 > UV531 > C944. For the optical performance, both UVAs and HALS could help to maintain the transmittance of visible light after photo-degradation. The former could effectively adsorb ultraviolet (UV) light and resulted in lower transmittance of UV light. For the polyester-plasticized PVC/PY systems, even though HALS and UVAs cannot help to maintain the shielding ability in high-energy visible region after UV irradiation, they can help prevent the loss in transmittance of visible light. The surface morphology exhibited small holes on the surface of the films that contain UV531 or UV326; while large and deep holes were observed on the surface of PVC films without additives, C944-doped and C944/PY-doped films, indicating the higher UV-stabilizing effect of UVAs. With regard to mechanical properties, UVAs and HALS can help to prevent the loss. Our present study systematically revealed the role of different stabilizers on the polyester-plasticized PVC and polyester-plasticized PVC/PY systems and paved the way to offer PVC materials with functional optical performance and desired long-term performance using different light stabilizers.