Abstract
The investigation of the influence of UV irradiation on polymers represents an important and relevant area of science and technology, as it enables the development of new approaches for designing more durable and efficient materials. This work examines the changes occurring in polymers based on unsaturated polyesters under prolonged exposure to ultraviolet radiation. The objective of the study was to evaluate the effect of long-term UV irradiation on the thermal stability of polymeric materials based on polyethylene glycol maleate and polypropylene glycol maleate copolymerized with acrylic acid at a component ratio of approximately 70:30 wt.%. The samples were examined using microscopy to identify microcracks formed as a result of UV exposure. In addition, visual assessment of color variation and the appearance of turbidity in the studied materials was performed. Additionally, the carbonyl index was determined to quantitatively evaluate the degree of photooxidative degradation of the polymers. This parameter characterizes the accumulation of carbonyl groups formed as a result of polymer chain scission under UV irradiation and allows estimation of the extent of photodegradation processes in the materials. The obtained results demonstrate that the polymer synthesized on the basis of polyethylene glycol maleate exhibited a more pronounced decrease in the onset temperature of thermal deformation after UV exposure compared with the copolymer based on polypropylene glycol maleate, indicating higher resistance of the latter to UV-induced degradation. The thermal stability of the copolymers was evaluated by thermogravimetric analysis through determination of the onset temperature of thermal deformation before and after 21 days of UV irradiation.