## 4 Discussion
[42] noted swelling in PLGA 75:25 solid compression molded scaffolds that turned whitish following 9 weeks of degradation at 37 \({}^{\circ}\)C. The increased water absorption due to swelling and change in appearance may be due to water molecules penetrating through the surface and causing a hydrolysis reaction, which increases the creation of water-insoluble low molecular weight polymers and oligomers in the outer layers [18]. For the scaffolds fabricated in this study, there is a higher surface area for the water molecules to penetrate the polymeric strands due to the high porosity. The change in mass loss and swelling goes hand in hand with the stable structural features of the scaffold observed during the degradation. The pH of PBS depleted to 7.11 towards the end of 28 days of degradation. This change in pH is crucial to consider since the hydrolysis reaction is catalysed by elevating the acidity of the degradation media [9]. Once the acidity reaches a critical rate, the degradation mechanism includes both bulk and surface degradation, leading to drastic changes in scaffold properties [50]. However, in the fabricated scaffolds, the change in the physiochemical properties remained stable and had not deteriorated drastically, indicating bulk degradation was not being induced. The DSC thermograms indicated an increase in crystallinity on day 21 and day 28 of accelerated degradation. As more water is absorbed into the polymer due to the large pore size within the scaffold, the oligomer chains released become smaller. The shorter and more mobile chains facilitate their rearrangement into a crystalline structure [9], confirmed by the increase in crystallinity. The molecular weight showed a rapid decline until day 28, when a whitish appearance was observed in the scaffold. Despite the decrease in molecular weight, the scaffolds retained their volumetric structure for 28 days, owing to the crystalline nature of the scaffolds. Furthermore, the mechanical properties of the scaffold observed a rapid decline in comparison to physiological degradation. The decrease in the equilibrium modulus was more drastic at accelerated degradation due to greater swelling and loss in mass of the scaffold. It was observed that this architecture of the fabricated 3D-printed PLLGA scaffolds could be treated for up to 28 days in PBS solution at an elevated temperature without critically affecting its properties. According to [PERSON] et al. [43], the degradation rates double when the temperature is raised by 10 \({}^{\circ}\)C. However, this does not account for the influence of the nature and molecular weight of the polymer and the geometry of the device, which are factors that can influence the degradation of these scaffolds [33; 44; 45; 46]. On comparing the change in properties at physiological and accelerated degradation conditions, the percentage decrease in mass on day 56 at 37 \({}^{\circ}\)C was similar to that of day 28 at 47 \({}^{\circ}\)C. A similar trend was also observed for the changes in pH and swelling. However, the change in Tg displayed a faster decline at accelerated degradation, with the Tg at day 7 at accelerated degradation being comparable to a time point between day 28 and day 42 at physiological degradation. On comparing the molecular weight, the Mn on day 56 of degradation at 37 \({}^{\circ}\)C was comparable to day 7 of accelerated degradation. Furthermore, on comparing the compressive properties, the decrease in ramp, equilibrium, and dynamic moduli was attained between day 10 and day 14 at accelerated degradation compared with 56 days of physiological degradation. This goes on to show that the degradation progresses through complex changes in the molecular and bulk properties of the scaffold due to multiple factors such as polymer composition, molecular weight, morphology, geometry, and the presence of residual monomers that can result in discrepancies in degradation rates [9].