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

Abstract

<jats:p> 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 (TiO<jats:sub>2</jats:sub>) 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/m<jats:sup>2</jats:sup> 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 TiO<jats:sub>2</jats:sub> 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. </jats:p>

Accelerated Degradation of Poly(lactide acid)/Poly(hydroxybutyrate) (PLA/PHB) Yarns/Fabrics by UV and O2 Exposure in South China Seawater

“…This result shows good agreement with Yu et al’s report on the degradation behavior of the transparent PLA films [ 25 ]. Such an appearance change might be induced by the variety of the internal crystal structure (e.g., crystallinity) of PLA/PHB and/or the change of chemical bond (e.g., the so-called “five-fingered” character in ester compounds [ 26 ]), since PLA exhibits slight to broad medium UV absorption bands below 400 nm through n-π* transition of carboxyl groups [ 27 , 28 ].…”

Effects of Printing Temperature and Filling Percentage on the Mechanical Behavior of Fused Deposition Molding Technology Components for 3D Printing

“…They observed that the melting temperature changed by 1-2 • C, and with the glass transition temperature of 70-80 wt%, LDPE increased by 4-5 • C. After irradiating with UV light, LDPE showed brittle failure with the increase in irradiation time. Can et al [23] investigated that the FDM technology for 3D printing, adding micron and nanometer size TiO 2 particles and benzotriazole as UV absorbers into PLA. They found that TiO 2 particles have a strengthening and toughening effect.…”

Aging of 3D Printed Polymers under Sterilizing UV-C Radiation

“…Rasselet et al undertook similar research for PLA [72]. Solutions for mitigating the effect of ultraviolet light on polymers exist in the form of UV stabilization additives that are used to absorb the most damaging parts of the UV spectrum and dissipate the absorbed radiation energy as heat [73,74]. The opposite effect can be reached through the use of photosensitizers to increase the biodegradability of materials [75].…”