Performance of polylactide against UV irradiation: Synergism of an organic UV absorber with micron and nano-sized TiO2

The research article “Performance of polylactide against UV irradiation: Synergism of an organic UV absorber with micron and nano-sized TiO2”, co-authored by METU member Prof. Cevdet Kaynak, has been published in Journal of Composite Materials.

The main purpose of this study was to investigate mechanical and thermal performance of polylactide specimens against UV irradiation; first when only adding benzotriazole benzotriazole-based organic UV absorber (UVA), micro (200 nm) and nano (50 nm) sized titania (TiO₂) particles alone, and then to reveal possible synergism when they are added together. Compounds were prepared by twin-screw extruder melt mixing, while the 2 mm thick specimens were shaped by compression molding. Specimens were exposed to UV irradiation under fluorescent lamps (UVB-313) with 0.50 W/m² for the periods of 12 and 24 days. Changes in the performance of UV irradiated specimens were evaluated in terms of % weight loss, changes in color and chemical structure, including the decreases in the mechanical and thermal properties. Various tests and analysis revealed that synergistic benefits of using micro and nano TiO₂ particles together with benzotriazole-type UVA were not only due to the effective stiffening, strengthening and toughening actions of titania particles, but also due to their very significant “UV screening” actions absorbing the photons of the UV irradiation, thus decreasing the degree of the detrimental photodegradation reactions leading to chain scissions in their PLA matrix.

Can, U., & Kaynak, C. (2020). Performance of polylactide against UV irradiation: Synergism of an organic UV absorber with micron and nano-sized TiO2. Journal of Composite Materials, 54(18), 2489-2504. doi:10.1177/0021998319899140

Article access: https://journals.sagepub.com/doi/10.1177/0021998319899140

Keywords:

benzotriazole; organic UV absorber; Polylactide; titania; UV irradiation

Other authors:

Can, U. (METU)