Preparation of Surface-Modified Zinc Oxide Nano-Filled PE Films and Their Weathering Resistance Under Different Indoor Artificial Accelerated Aging Methods

When used outdoors, polyethylene (PE) film is exposed to ultraviolet radiation with a wavelength of 300 nm, causing molecular chain breakage and leading to deterioration of the film's mechanical properties. To enhance the film's weather resistance, this study modified nano-ZnO (zinc oxide) using different coupling agents. The ultraviolet transmittance and mechanical properties of PE films modified with nano-ZnO incorporating various coupling agents were investigated. The γ-aminopropyltriethoxysilane coupling agent (KH550) was selected. The KH550-ZnO/PE film achieved a tensile strength of 34.2 MPa while providing effective UV shielding with minimal visible light blocking. The aging behavior of KH550-modified nano-ZnO-filled PE films under indoor accelerated aging conditions was investigated. By comparing the mechanical properties and UV shielding performance of PE films with varying nano-ZnO concentrations, the optimal loading was determined to be 4 wt%. PE films containing 4 wt% nano-ZnO demonstrated superior weather resistance in pure UV aging tests, maintaining 88.22% tensile strength retention after 40 days of pure UV exposure. In thermo-oxidative aging tests without UV influence, the 4 wt% maintained a tensile strength retention rate of 69.23%. However, in the thermo-oxidative photoaging test, the presence of moisture led to increased hydroxyl radical generation under the photocatalytic effect of nano-ZnO. This resulted in degradation of the modified PE film segments by hydroxyl radicals, manifesting as reduced tensile strength. Furthermore, three-dimensional polymer aging visualization revealed that changes in carbonyl and carboxyl groups within the film also followed the aforementioned aging patterns. This work aims to extend the service life of agricultural films used in high-temperature, dry environments by incorporating modified nano-ZnO.