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Molecular relaxation in cross-linked poly(ethylene glycol) and poly(propylene glycol) diacrylate networks by dielectric spectroscopy
Authors:Sumod Kalakkunnath  Haiqing Lin  Roy D. Raharjo
Affiliation:a Department of Chemical and Materials Engineering and Center for Manufacturing, University of Kentucky, 177 Anderson Hall (Tower), Lexington, KY 40506-0046, United States
b Center for Energy and Environmental Resources, Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78758, United States
Abstract:
The molecular relaxation characteristics of rubbery amorphous crosslinked networks based on poly(ethylene glycol) diacrylate [PEGDA] and poly(propylene glycol) diacrylate [PPGDA] have been investigated using broadband dielectric spectroscopy. Dielectric spectra measured across the sub-glass transition region indicate the emergence of an intermediate “fast” relaxation in the highly crosslinked networks that appears to correspond to a subset of segmental motions that are more local and less cooperative as compared to those associated with the glass transition. This process, which is similar to a distinct sub-Tg relaxation detected in poly(ethylene oxide) [PEO], may be a general feature in systems with a sufficient level of chemical or physical constraint, as it is observed in the crosslinked networks, crystalline PEO, and PEO-based nanocomposites.
Keywords:Membranes   Poly(ethylene oxide)   Dielectric spectroscopy
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