13 June 1997 Dielectric relaxation phenomena in polymers: recent findings by chemical vitrification experiments
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Proceedings Volume 3181, Dielectric and Related Phenomena: Materials Physico-Chemistry, Spectrometric Investigations, and Applications; (1997) https://doi.org/10.1117/12.276275
Event: Dielectric and Related Phenomena: Materials Physico-Chemistry, Spectrometric Investigations, and Applications, 1996, Szczyrk, Poland
Abstract
A novel approach to the dielectric analysis of relaxation phenomena in glass-forming liquids is discussed. Instead of cooling, the system is polymerized so that the glass transition is approached by a chemical vitrification process. Measurements were carried out in a wide frequency interval covering 7 decades, from 103 to 1010 Hz, on different polymerizing systems, namely two epoxy systems, the butyl acrylate and an unsaturated polyester. The relaxation function adopted for extracting the dielectric parameters is validated through a careful verification of the chemical and physical meaning of the changes observed in the dielectric susceptibility as the reaction goes on. The evolution of the shape of the relaxation function is discussed within the percolation theories developed or undercooled liquids and a satisfactory agreement between experimental results and theoretical predictions was found. The scaling behavior vs. conversion of relaxation times of both main and secondary processes closely parallels those observed in many glass-formers vs. temperature and it can well be represented by Vogel Fulcher-like Arrhenius-like equations, respectively.
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Pierangelo A. Rolla, Pierangelo A. Rolla, A. Livi, A. Livi, Simone Capaccioli, Simone Capaccioli, Daniele Fioretto, Daniele Fioretto, } "Dielectric relaxation phenomena in polymers: recent findings by chemical vitrification experiments", Proc. SPIE 3181, Dielectric and Related Phenomena: Materials Physico-Chemistry, Spectrometric Investigations, and Applications, (13 June 1997); doi: 10.1117/12.276275; https://doi.org/10.1117/12.276275
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