title: Effects of Solvent Crystallization in Swollen net-Poly(ethyl acrylate) α Relaxation Dynamics.
abstract: The polymer α relaxation process for net-PEA gels swollen with nonpolar p-xylene is studied by employing dielectric relaxation spectroscopy. The results present the in situ monitoring of the dielectric behavior of α relaxation process under p-xylene cold crystallization, isothermal crystallization as well as crystallization from quenching. For the partially crystallized systems, the results exhibit that the amount of p-xylene crystal phase has no remarkable effects on the time scale, being controlled mainly by the amount of the noncrystallized p-xylene (cpx= 0.11-0.15) gel phase. Surprisingly, the stretching exponent βKWWobtains higher values in the isothermal crystallization process as the p-xylene crystallization is in progress and the reorganization of p-xylene through diffusion to crystallites approaches thermodynamic equilibrium. This directly indicates that any α process broadening is originated not solely from the amount of p-xylene crystallites and the induced heterogeneities, but from the presence of remarkable concentration fluctuations close to respective effective glass transition temperature, enhanced for higher solvent contents as well. Finally, the results suggest that the existence of p-xylene crystallites decrease significantly the dielectric strength of α process. The effective medium theory is applied to check whether this recorded reduction originates from the induced spatial heterogeneities (p-xylene crystallites) or from the immobilization in parts of polymer configurations.
authors.affiliation: Department of Physics, National Technical University of Athens , Zografou Campus, 15780 Athens, Greece.
authors.forename: Andreas T
authors.identifier: 0000-0001-5175-3705
authors.initials: AT
authors.lastname: Stathopoulos
authors.affiliation: Department of Physics, National Technical University of Athens , Zografou Campus, 15780 Athens, Greece.
authors.forename: Apostolos
authors.initials: A
authors.lastname: Kyritsis
authors.affiliation: Department of Physics, Tokai University , Hiratsuka, Kanagawa 259-1292, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Shinyashiki
authors.affiliation: Centro de Biomateriales e Ingeniería Tisular, Universidad Politecnica de Valencia , P.O. Box 22012, E-46071 Valencia, Spain.|Regenerative Medicine Unit, Centro de Investigación Príncipe Felipe , Autopista del Saler 16, 46013 Valencia, Spain.|CIBER en Bioingeniería, Biomateriales y Nanomedicina , 46012 Valencia, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Gómez-Ribelles
authors.affiliation: Department of Physics, National Technical University of Athens , Zografou Campus, 15780 Athens, Greece.
authors.forename: Polycarpos
authors.initials: P
authors.lastname: Pissis