Explication of mechanism governing atmospheric degradation of 3D-printed poly(lactic acid) (PLA) with different in-fill pattern and varying in-fill density

Abstract

With accelerated weathering test instruments lacking the ability to correlate with actual instabilities during application, this work makes an attempt to explore the degradation of PLA under natural atmospheric conditions of UV, rain and humidity.

Effect of Degradation on the Physicochemical and Mechanical Properties of Extruded Films of Poly(lactic acid) and Chitosan

“…Additionally, similar to the PLA, this film presented a peak around 895 cm –1 at 144 and 192 h of exposure (Figure d). Furthermore, during the latter two times T5-T6, another new signal was observed at 920 cm –1 , which is attributed to the asymmetric bending of double bonds, as previously mentioned, is associated with the photodegradation of the PLA within the composite film. − Finally, similar to Q1, the Q2 film exhibited the peak associated with hydrolysis at 3390 cm –1 ; however, this peak only appeared after 288 h of degradation (Figure e). Its appearance during the final degradation period (T6) may indicate the higher resistance of this film to the degradation process.…”

“…The spectrum of the PLA film (Figure b) presented a new peak at around 895 cm –1 after 240 h of exposure. This signal is attributed to the symmetric bending of a double bond in acrylate residues resulting from the Norrish type II photodegradation of the polymer (Figure a). , On the contrary, it proved challenging to identify other changes in the infrared spectrum associated with alternative degradation mechanisms, possibly due to this film’s pronounced resistance to degradation. On the other hand, the Q1 film (Figure c) displayed a new peak around 3412 cm –1 at 240 h of exposure, which can be attributed to the stretching of the hydroxyl (OH) group, associated with chitosan hydrolysis within the film (Figure b) .…”