caa a22 4500 378903748 CHVBK 20180305123524.0 cr unu---uuuuu 161128e20041201xx s 000 0 eng 10.1515/epoly.2004.4.1.455 doi (NATIONALLICENCE)gruyter-10.1515/epoly.2004.4.1.455 Dielectric and hydration properties of segmental polyurethanes [Elektronische Daten] [Konstantinos Raftopoulos, Ioannis Zegkinoglou, Athanasios Kanapitsas, Sotiria Kripotou, Iraklis Christakis, Aglaia Vassilikou-Dova, Polycarpos Pissis, Yuri Savelyev] Novel polyurethanes (PUs), based on oligo(oxytetramethylene glycol), 4,4'-diphenylmethanediisocyanate and 1,1-dimethylhydrazine as chain extender, were prepared in a two-step process. The ratio prepolymer (PP) to chain extender (CE) was systematically varied in extreme ranges, from 1:1 to 10:1. Dielectric relaxation spectroscopy and thermally stimulated depolarization currents (TSDC) techniques were employed to investigate molecular dynamics and to conclude on microphase separation (MS). In that respect TSDC was proven to be very powerful, in particular as far as the investigation of the interfacial Maxwell-Wagner-Sillars polarization is concerned. Additional information on micromorphology is obtained from water sorption/diffusion measurements. A part of the results suggest that MS improves with increasing the PP:CE ratio. The whole body of results can be explained if, at the same time, it is assumed that a branched structure is developed for samples out of stoichiometry and branching increases with increasing the PP:CE ratio. Preliminary experiments with solutions of the PUs in organic solvents provide support for that assumption. © 2013 by Walter de Gruyter GmbH & Co. Raftopoulos Konstantinos Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Greece aut Zegkinoglou Ioannis Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Greece aut Kanapitsas Athanasios Department of Physics, National Technical University of Athens, 15780 Zografos Greece aut Kripotou Sotiria Department of Physics, National Technical University of Athens, 15780 Zografos Greece aut Christakis Iraklis Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Greece aut Vassilikou-Dova Aglaia Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Greece aut Pissis Polycarpos Department of Physics, National Technical University of Athens, 15780 Zografos Greece aut Savelyev Yuri Institute of Macromolecular Chemistry, National Academy of Sciences of Ukraine, Harkivske shose 48, 02160 Kyiv, Ukraine aut e-Polymers De Gruyter 4/1(2004-12-01), 455-469 2197-4586 4:1<455 2004 4 epoly https://doi.org/10.1515/epoly.2004.4.1.455 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1515/epoly.2004.4.1.455 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Raftopoulos Konstantinos Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Greece aut NATIONALLICENCE 700 1- Zegkinoglou Ioannis Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Greece aut NATIONALLICENCE 700 1- Kanapitsas Athanasios Department of Physics, National Technical University of Athens, 15780 Zografos Greece aut NATIONALLICENCE 700 1- Kripotou Sotiria Department of Physics, National Technical University of Athens, 15780 Zografos Greece aut NATIONALLICENCE 700 1- Christakis Iraklis Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Greece aut NATIONALLICENCE 700 1- Vassilikou-Dova Aglaia Section of Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Greece aut NATIONALLICENCE 700 1- Pissis Polycarpos Department of Physics, National Technical University of Athens, 15780 Zografos Greece aut NATIONALLICENCE 700 1- Savelyev Yuri Institute of Macromolecular Chemistry, National Academy of Sciences of Ukraine, Harkivske shose 48, 02160 Kyiv, Ukraine aut NATIONALLICENCE 773 0- e-Polymers De Gruyter 4/1(2004-12-01), 455-469 2197-4586 4:1<455 2004 4 epoly CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter