Natural weathering behavior and photo stability improvement of poly (butylene succinate-co-butylene terephthalate)-based mulch films under two typical climatic conditions

Abstract

The weather resistance of PBST films is the key performance of their application in agricultural films. Ultraviolet (UV) absorbers based on benzophenones are extensively used light stabilizers. Therefore, UV absorber-modified poly(butylene succinate-co-butylene terephthalate) (PBST) films were fabricated and subjected to natural weathering studies in Xinjiang and Hainan, China. The chemical structure and tensile, optical, and thermal properties of the films before and after natural weathering were investigated using a high-speed extensometer and an enhanced projection haze shadow meter in addition to differential scanning calorimetry, scanning electron microscopy, Fourier-transform infrared spectrometry, and wide-angle X-ray diffraction. The significant deterioration of toughness in the transverse direction is an important reason for the decreased serviceability of the films after weathering. The weathered PBST films in Hainan are more likely to lose their serviceability. Adding UV absorbers significantly improves the weathering resistance of the PBST films; the retention of tensile strength and elongation at break of PBST are doubled, and the crystallinity retention is increased by approximately 50% after natural weathering, with sufficient light transmission. These findings provide guidelines to increase the weathering resilience of PBST films, which may be utilized to efficiently and economically fabricate agricultural films.