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Direct relationships between volume variations at macro and nanoscale in epoxy systems. PALS/PVT measurements |
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| Authors: | S Goyanes W Salgueiro JA Ramos |
| Affiliation: | a LPyMC, Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires and Consejo Nacional de Investigaciones Científicas y Tecnológicas, Argentina b IFIMAT-UNCentro and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, Pinto 399, B7000GHG Tandil, Argentina c Materials + Technologies Group, Dpto. Ingeniería Química y M. Ambiente, Escuela Univ. Politecnica, Universidad País Vasco/Euskal Herriko Unibertsitatea, Pz. Europa 1, 20018 Donostia/San Sebastián, Spain |
| Abstract: | The free volume in epoxy systems fully cured with aminic hardeners having different chemical structures was studied by means of positron annihilation lifetimes spectroscopy. The results are compared with those obtained from the analysis of the macroscopic specific volume changes by using pressure-volume-temperature experimental technique. An excellent correlation between the volumes measured at macro and nanoscales was found. From this fact, it can be asserted that the variation of the specific volume is mainly controlled by the variation in the average size of sub-nanometer size local free volumes, which are fixed by the chemical structure of hardener in fully crosslinked epoxy networks. These results give the first evidence of the direct relation existing between macro and nanoscales in thermosetting networks. |
| Keywords: | Epoxy Hardener Chemical structure |
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