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Nanohole volume dependence on the cure schedule in epoxy thermosetting networks: A PALS study |
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| Authors: | W Salgueiro A Somoza S Goyanes I Mondragón |
| Affiliation: | a Instituto de Física de Materiales Tandil (IFIMAT), Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, B7000GHG Tandil, Argentina b Materials+Technology Group, Departamento de Ingeniería Química y M. Ambiente, Escuela Univ. Politécnica, Universidad País Vasco/Euskal Herriko Unibertsitatea, Pz. Europa 1, 20018 Donostia/San Sebastián, Spain c Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, Calle 526 e/10 y 11, 1900 La Plata, Argentina d LPMPyMC, Depto. de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón I, 1428 Buenos Aires, Argentina e CONICET, Buenos Aires, Argentina |
| Abstract: | A systematic study on the dependence of the volumes at nanoscale in epoxy systems cured with two selected aminic hardeners at different pre-cure temperatures is presented. Nanohole volumes were measured by positron annihilation lifetime spectroscopy. Additional information regarding the structure of the thermosets was obtained using dynamic mechanical analysis. Volume results obtained are discussed in terms of the cure schedule applied to the epoxy systems, their characteristic glass transition temperatures and their crosslink density. The pre-cure temperature and the structure of the hardeners govern the packing of the molecular chains of the epoxy network. Using together positron and mechanical experimental techniques allows to conclude that a strong change in the volume and number density of the nanoholes takes place when the pre-cure temperature crosses the glass transition temperature of the systems. |
| Keywords: | Epoxy Hardener Cure schedule |
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