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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 54: Poster Session 3

CPP 54.75: Poster

Donnerstag, 3. April 2014, 15:00–19:00, P2

Unexpected low-frequency dynamics in DGEBA/SiO₂ — •Rick Dannert¹, Patrick Elens¹, Matthieu Thomassey², Jörg Baller¹, and Roland Sanctuary¹ — ¹Laboratory for the Physics of Advanced Materials, University of Luxembourg — ²G2IP / ICPEES CNRS UMR 7515 - ECPM / University of Strasbourg (France)

We investigate the complex rheological behaviour of nanocomposites based on low molecular weight epoxy resins. The resin consists of DGEBA (diglycidylether of Bisphenol-A ) with different degrees of polymerization (monomers, dimers, trimers). The nanoparticles (diameter: 25 nm) consist of silica coated with a thin silane layer to achieve a good dispersion. In order to investigate the relaxation behaviour of the complex shear moduli, we exploit dynamic rheology at temperatures higher than the thermal glass transition temperature (258K). Measurements of the pure viscoelastic DGEBA system show powerlaw behaviour. The dynamic glass transition is shifted to lower frequencies by adding nanoparticles. In addition to the alpha process, the shear moduli show unexpected relaxations at much lower frequencies. These low-frequency relaxations are systematically investigated for different nanoparticle concentrations and by changing the relaxation dynamics of the matrix molecules. The latter is done by specifically modifying the length of the matrix molecules, e.g. by using dimers instead of monomers.