Entanglement dynamics in ultra-high molecular weight polyethylene as revealed by dielectric spectroscopy. (15th August 2018)

• Record Type: Journal Article
• Authors: Drakopoulos, Stavros X.; Psarras, Georgios C.; Forte, Giuseppe; Martin-Fabiani, Ignacio; Ronca, Sara
• Is Part Of: Polymer. Volume 150(2018)
• Page Start: 35
• Page End: 43
• Publication Date: 2018-08-15
• Subjects: Ultra-high molecular weight polyethylene -- Entanglement formation -- Broadband dielectric spectroscopy; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2018.07.021
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: With the help of Broadband Dielectric Spectroscopy, it has been possible to study the molecular dynamics of disentangled Ultra High Molecular Weight Polyethylene in a wide temperature and frequency range. Catalytic ashes of aluminum oxide act as dielectric probes, allowing the identification of five different processes: an αc -process due to movements in the crystalline phase, two γ-processes attributed to amorphous chain portions close to the crystalline lamellae, and two β-processes that we have attributed to the disentangled and entangled amorphous phases. The entanglement formation has been followed by isothermal runs and a model that predicts the energy spent to form entanglements as a function of time and temperature is thereby proposed. This model allowed us to calculate the associated activation energy of the entanglement process. Our work advances further the understanding of entanglement dynamics of ultra-high molecular weight polymers, and the proposed model could prove useful to describe other similar processes such as cross-linking. Graphical abstract: Image 1 Highlights: Dielectric analysis of disentangled UHMWPE in the presence of Al2 O3 was performed. Two different relaxations correspond to the disentangled and entangled amorphous regions. Entanglement dynamics as a function of temperature and time in dis-UHMWPE samples. A model was proposed to calculate the activation energy of entanglement formation.