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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Modeling and Simulation of Soft Matter II
CPP 21.5: Vortrag
Dienstag, 18. März 2025, 15:00–15:15, H34
Influence of hydroxyl groups on the dielectric constant of polyethylene — •Roshal Perepadan Shaju1, Guido Roma1, and Xavier Colin2 — 1Université Paris-Saclay, CEA, Service de recherche en Corrosion et Comportement des Matériaux, SRMP, Gif sur Yvette, 91191, France — 2PIMM, Arts et Métiers Institute of Technology, CNRS, CNAM, HESAM University, 151 Boulevard de L'Hôpital, 75013 Paris, France
Polyethylene (PE) is widely used as an insulation for electric cables in various environments, including nuclear power plants. PE is susceptible to chemical modifications when exposed to ionizing radiation and oxidative environments. Introducing polar functional groups to this semi-crystalline PE, such as carbonyls and hydroxyl (OH) groups, has been observed to modify its dielectric response. However, the precise influence of hydroxylation on the dielectric properties of semi-crystalline PE is still inadequately understood. In this paper, we employ DFT and Density Functional Perturbation Theory (DFPT) to systematically investigate the effect of OH groups on the dielectric properties of semi-crystalline PE. By modeling PE with distinct surface, amorphous, and crystalline regions, the complexity of its semi-crystalline nature is explored. The static and high-frequency dielectric constants of polyethylene systems with different concentrations of OH groups were determined. The orientation of the OH defect relative to various crystallographic axes is thoroughly examined in order to determine how the alignment of the defects in the crystal lattice may affect the dielectric tensor.
Keywords: Polyethylene; DFPT; Hydroxyl defect; Dielectric constant; Radio-oxidation