Atomic scale insights on the degradation process were obtained by using Identical Location TEM--microscopic techniques developed to track morphological changes of the catalysts material at the nanoscale level [2]. The obtained results were correlated with inductively coupled plasma mass spectrometry (ICP-MS), Ramman spectroscopy, and Electron Energy Loss Spectroscopy. Figure 40: (a) XRD patterns of PE-RT/GNPs and (b) thermal conductivity measurements of PEX/GNPs and PE-RT/GNPs nanocomposites. **Acknowledgments:** This work was financially supported by NCN 2019/33/B/ST5/02702. ## References  
* (1) O'Mayre, R.; Cha, S.W. ; Colella, W.; Prinz, F.B. _Fuel Cell Fundamentals_; John Wiley & Sons: Hoboken, NJ, USA, 2016. * (2) Arenz, M.; Zana, A. Fuel cell catalyst degradation: Identical location electron microscopy and related methods. _Nano Energy_**2016**, _29_, 299-313. * (3)_18.4. Preparation and Characterization of Biocompatible Poly(lactic acid)/Poly(ethylene adipate) Blends_
* (4)**M. Lazaridou, C. Samiotaki
* and D. N. Bikiaris *
* (5) Laboratory of Chemistry and Technology of Polymers and Dyes, Chemistry Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
* (6) Correspondence: christinasamiotaki@gmail.com (C.S. ); dbic@chem.auth.gr (D.N.B.) Poly(lactic acid), PLA, is a highly biocompatible polyester that has concentrated a lot of interest in the last few decades. However, despite its unique properties and characteristics, this polyester requires a long time for its biodegradation to be completed, and for that it tends to be combined with other biodegradable polymers. This can happen through copolymerization or with the synthesis of polymeric blends, as is this particular case. The purpose of this study is the synthesis of poly(ethylene adipate), PEAd, another aliphatic linear biodegradable polyester, and the deconstruction of the impact this polymer has on the characteristic properties of poly(lactic acid) (such as the biodegradation rate). The synthesis of poly(ethylene adipate) was performed by a two-step melt polycondensation process (esterification and polycondensation) with tributyltin as catalyst [1]. The polymeric blends were prepared by the solution casting method in five different ratios: PLA/PEAd: 90/10, 80/20, 70/30, 60/40, and 50/50. Both poly(ethylene adipate) and the mixtures were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). In addition, viscosity, tensile strength, and enzymatic hydrolysis of the blends were studied. FTIR spectroscopy confirmed the successful synthesis of poly(ethylene adipate), while FTIR of the mixtures revealed interactions between the reactants (Figure 41). Concerning the mixtures, DSC analysis showed reduced melting point temperature and glass transition compared to neat PLA. Viscosity study revealed a notable increase in the molecular weight and intrinsic viscosity of the polymeric blends as PLA content increases. From the tensile measurements, it became clear that the absolute tensile strength increases with the increase in the PLA content of the mixtures, but we must emphasize that the tensile strength reaches up to a point and then decreases, i.e., it acquires a maximum. Finally, enzymatic hydrolysis revealed that, as the content of the mixtures in PEAd increases, the films present a greater hydrolysis rate. In order to gain a better insight into the enzymatic hydrolysis process, morphological examination of the samples was performed by scanning electron microscope (SEM) (Figure 42). Figure 41: FTIR spectra of PLA-PEAd blends. ## References  
* _Karavelidis et al. (2015)_ Karavelidis, V.; Bikiaris, D.; Avgoustakis, K. New thermosensitive nanoparticles prepared by biocompatible pegylated aliphatic polyester block copolymers for local cancer treatment. _J. Pharm. Pharmacol._**2015**, 67, 215-230. * _18.5.