Experimental investigation into flexural and impact behaviour of 3D printed PETG short carbon fibre composite under solar light irradiation

Polymeric materials exposed to sunlight radiation and environmental conditions experience severe surface degradation, affecting the material physical and mechanical properties. The interaction of sunlight with material results in photolytic, photooxidative, and thermo oxidative reactions, all of which are considered major degradation processes. In this study, a 3D printed PETG carbon fibre composite was exposed to sunlight for 10, 20 and 30 days, and the resulting degradations of impact and flexural properties were studied and analysed. The experiment revealed that the flexural and impact properties of the specimens deteriorated as the specimen exposure time increased, with the impact properties deteriorating more sharply than the flexural properties. To determine and comprehend the cause of the degradation, irradiated specimens were subjected to a Fourier transformation infrared spectroscopy (FTIR) test, and the evolved peaks in the FTIR plot of degraded specimens were compared to untreated specimens. Furthermore, the effect of irradiation on the bulk domain of the printed specimens is investigated using scanning electron micrography on fractured specimens. It is observed that irradiation had little effect on the geometrical properties of the bulk zone (mesostructure), and the formation of the mesostructure was largely influenced by infill density and layer thickness. An in-depth scanning electron microscopy study is carried out to investigate the reasons for the influence of mesostructure on fracture initiation to termination in the specimens caused by impact load.