Weathering of chitosan films in the presence of low- and high-molecular weight additives

The effects of artificial solar radiation from an Accelerated Weathering Chamber (Weatherometer) on thin chitosan films were studied by UV–Vis and FTIR spectroscopy, contact angle measurements, microscopy methods and mechanical properties investigation. Chitosan films were prepared through a solution casting method. Several films were prepared with low- and high-molecular weight additives, such as camphorquinone, glutathione, tyrosine, phenylalanine and collagen. It was found that UV–Vis spectra, which characterize chitosan, were significantly altered by artificial solar radiation. The thermal properties and polarity of the surface were also altered by artificial solar light. Mechanical properties such as the ultimate tensile strength, percentage elongation and Young's modulus of chitosan films were changed irregularly according to irradiation time. The deterioration of the mechanical properties of chitosan films after irradiation results mainly from photochemical changes such as cross-linking and chain scission. The contact angle and the surface free energy of chitosan films were altered by artificial solar UV irradiation. The influence of low- and high-molecular weight additives on photodegradation of chitosan has also been discussed.