Probing the molecular dynamics in XLPE aged at different temperatures by 1H NMR relaxation time measurements

Autor:	Jobby Paul, Jaan Roots, Eddy W. Hansen
Rok vydání:	2012
Předmět:	Thermal oxidation Materials science Polymers and Plastics Drop (liquid) Relaxation (NMR) Analytical chemistry Polyethylene Condensed Matter Physics Amorphous solid Molecular dynamics chemistry.chemical_compound chemistry Mechanics of Materials Materials Chemistry Melting point Proton NMR
Zdroj:	Polymer Degradation and Stability. 97:2403-2411
ISSN:	0141-3910
DOI:	10.1016/j.polymdegradstab.2012.07.022
Popis:	Ageing of cross-linked polyethylene (XLPE) insulation used in high voltage cable was monitored using low-field solid-state 1 H NMR. The effect of thermal ageing at different temperatures on the phase composition and molecular mobility was studied by 1 H NMR relaxation time experiments. The onset and progress of oxidation is observed to be very different for XLPE aged at different temperatures. Crystalline fraction dropped monotonically after the onset of oxidation for sample aged above melting point while it remained constant after a small initial drop for the sample aged near the melting point. Thermal oxidation caused a drastic change in molecular dynamics of the amorphous region as indicated by the change in correlation time. Thermal oxidation is confined to the amorphous region in the case of sample aged close to the melting point. The change in phase composition and relaxation time suggest that chain scission was predominant during the early stages of oxidation and later dominated by crosslinking. The presence of antioxidant prolonged the onset of oxidation depending on the ageing temperature.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::0f6b946111de260774a3687f16daec3d https://doi.org/10.1016/j.polymdegradstab.2012.07.022 Zobrazit plný text záznamu Full Text from ScienceDirect