Browsing by Author "Alegria, Luz"

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    Water sorption by poly(tetrahydrofurfuril methacrylate)'s
    (WILEY, 2008) Sanchis, Maria J.; Diaz Calleja, Ricardo; Garcia Bernabe, Abel; Alegria, Luz; Gargallo, Ligia; Radic, Deodato
    Polymers consisting of poly(heterocyclic methacrylate)s are considered as potential materials for clinical applications such as drug delivery and cartilage repair. Much of the success of these systems has been attributed to the complex nature of their water sorption properties. Dielectric permittivity is very sensitive to water sorption. Dielectric relaxation spectroscopy studies have been carried out on two heterocyclic poly(methacrylate)s: poly(tetrahydrofurfuryl methacrylate) (PTHFMA) and poly (3-methyl tetrahydrofurfuryl methacrylate) (P3MTHFMA). The isochrones representing the dielectric losses show in both cases high conductivity at low frequencies and high temperatures. In PTHFMA two conductive processes are observed, which can be associated to the existence of two types of water sorption. These effects have been analyzed and were removed from the dielectric spectra by using classical empirical equations. Both polymers show ostensible alpha-relaxation centered in the vicinity of 350 K at 10(0) Hz. This relaxation was analyzed by means of the empirical Havriliak-Negami equation. Reminiscent beta-relaxation could also exist. Both polymers present well defined gamma and delta subglass absorptions at approximately 120 K, 160 K for PTHFMA and 125 K, 163 K for P3MTHFMA, at 10(0) Hz, associated to local intramolecular relaxations in side groups. These relaxations were analyzed using semiempirical symmetric model. (C) 2007 Wiley Periodicals, Inc.