## 4 Discussion
A small drop in pH over the 56 days confirmed the stable crystalline nature of the polymer in combination with the highly porous structure, aiding in a low build-up of acidic byproducts. The change in thermal characteristics from the DSC thermograms displayed a small decrease in T\({}_{\text{g}}\) of 0.55 \({}^{\circ}\)C (Table 2). This is also indicative of a low change in acidity in the PBS solution. A small drop in T\({}_{\text{g}}\) is indicative of surface degradation occurring due to the chain scission of oligomers on the surface of the polymer [39]. PLA has a methyl side chain, which is denser and less hydrophilic than PGA. As a result, lactic-rich PLLGA 85:15 copolymers absorb less water and disintegrate more slowly [40]. It has been stated that the chemical composition, hydrophobicity of the polymer, polymeric device's architecture, and how easily the scaffold may be accessed by degrading media are significant elements that affect degradation [41]. The changes in molecular weight of the scaffolds provided further information on the degradation mechanism. The molecular weight decreased before any changes in the mass loss. When water diffuses into a polymer, hydrolysis starts, and degradation then happens in two phases where a decrease in molecular weight is seen before any mass loss [8; 42]. Furthermore, the gradual decrease in molecular weight of the scaffold to day 56 has been previously observed by [PERSON] et al. [9]. The low decrease in the molecular weight of the polymer can be associated with random chain scission occurring in the polymer. As the molecular weight in the scaffold drops due to random chain scission, there is initially no mass loss since the chains created are too big to diffuse outside of the polymer matrix. It can be stated that the polymer chains did not reach a critical length corresponding to a significant drop in molecular weight, which resulted in low changes in mass loss and swelling within the fabricated scaffolds [43]. The ramp modulus of the scaffold decreased by 25.90% for over 56 days. The gradual decrease can be attributed to the slow degradation of the scaffold material as ramp testing involves a biphasic response of the scaffold from both fluid pressurisation and the scaffold's solid phase being deformed [44]. The equilibrium modulus is a measure of the solid phase of the scaffold bearing the compressive load when fluid is no longer flowing through the scaffold. In this regard, the material's behaviour is comparable to the solid phase of the cartilage [45]. The degradation of the scaffold yielded a maximum decrease in the equilibrium modulus because of the degradation in the solid matrix of the scaffold. Another notable factor is the swelling of the scaffold strands. The fluid retained within the strands of the scaffold provides additional biphasic response even when the interstitial fluid has stopped flowing. The swelling observed over 56 days of degradation, along with mass loss, was comparable to the percentage decrease in the equilibrium modulus, which was related to the decrease in the equilibrium modulus as the scaffold degrades. The decrease in the equilibrium modulus was well within a comparable range of the native cartilage, which showcased the stable functional strength of the scaffold [12]. This phase was followed by a cyclic displacement during a dynamic test. Fluid pressurisation in the pores of the scaffold supports a sizeable portion of the force used in such dynamic testing for normal articular cartilage [44]. Therefore, the dynamic modulus sheds light on both the permeability and compressive stiffness of the designed scaffold during cyclic loading. Furthermore, the dynamic properties of the scaffold are dependent on the amount of strain applied to the scaffold. The articular cartilage experiences a cyclic loading between 10-20% strain amplitude at 1 Hz frequency, depending on the activity [46].