A number of experimental studies have demonstrated that the dielectric loss peak that is characteristic of the β-relaxation process spans a wide range of frequencies. It has been suggested that, depending on the polymer, the β-relaxation process can be attributed to the re-orientational motions of a side group or the local motions of the polymer chain backbone, which is independent of the cooperative motion of surrounding chains. In polymer systems, more than one secondary relaxation can exist. It is worth highlighting the Johari-Goldstein (JG) β-relaxation, sometimes also referred to in the literature as the slow β-relaxation. The JG β-relaxation is considered a universal feature of all disordered materials, and, like all higher order relaxation processes, is observed at higher frequencies than the α-relaxation. For a long time there has been a lively discussion regarding the exact physical nature of the higher order relaxation processes and whether such processes are indeed distinctly different from one another. Given this situation, it is not surprising that the terminology of the secondary relaxation processes mostly depends on the traditions developed by each respective community. It is sometimes suggested that the JG β-relaxation process relates to intermolecular degrees of freedom, in contrast to the general β-relaxation process which is intramolecular in nature. Such a view is in direct contrast to the more nuanced potential energy surface (PES) model proposed by Goldstein almost half a century ago. Recent experimental and theoretical work clearly highlights that the PES approach is the most intuitive and comprehensive model to understand the molecular dynamics in disordered systems and that intra-and intermolecular processes are always fundamentally coupled by means of the PES. Poly lactic-co-glycolic acid (PLGA) is a biodegradable and biocompatible copolymer that has found widespread application in biomedical applications. It is soluble in a wide range of solvents and is thermally stable, with no appreciable weight loss observed at temperatures below 473 -523 K. While the overall mechanical properties of PLGA have been investigated in detail the relaxation properties of the material are less well understood.