Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 1: Nanoparticles and Composite Materials I

CPP 1.2: Vortrag

Montag, 11. März 2013, 10:00–10:15, H34

Investigation of particle-induced confinement effects on free volume in PEP-Silica Nanocomposites — •Christian Ohrt¹, Tönjes Koschine¹, Stephan Harms¹, Klaus Rätzke¹, Franz Faupel¹, Lutz Willner², and Gerald Schneider³ — ¹Materialwissenschaft-Materialverbunde , Universität Kiel, 24143 Kiel — ²Jülich Centre for Neutron Sciene 1 and Institut for Complex Systems Forschungszentrum Jülich, D-52425 Jülich — ³Forschungs-Neutronenquelle Heinz Maier-Leibnitz 85747 Garching Germany

PPolymer nanocomposites are widely used due to improved properties compared to pure polymers. Some of the improved properties can be a result of a so called interphase, a part with a modified free volume, resulting from the interaction between nanoparticles and polymer or they can be a consequence of the restricted mobility of polymer chains due to the nanoparticles, usually termed confinement. Positron annihilation lifetime spectroscopy (PALS) can be used to investigate the influence of nanoparticles in a polymer matrix on the free volume. We analysed the change in free volume due to confinement in a weakly repulsive system consisting of poly(ethylene-alt-propylene) (PEP) with different molecular weights and silica nanoparticle concentrations by PALS and thermal properties by DSC. DSC showed no change in glass transition temperature, whereas PALS showed an increase in o-Ps lifetimes for low temperatures and a decrease for high temperatures with increasing filler concentration, which can be explained by a mixing rule of o-Ps lifetimes of the pure constituents. Thus no interphase is formed and the dynamics of the polymer are not affected by confinement.