Influence of non-linear mechanical stress on the molecular dynamics of composite materials via simultaneous Rheo-NMR and Rheo-SAXS characterisation

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The high surface area in nano-scaled composite materials and the large volume fraction of the resulting polymer-solid interphase influence strongly the properties of the resulting materials. One important aspect is the mechanical behaviour and the response of composite materials under mechanical stress, especially non-linear stress usually applied during processing and utilization of polymers and polymer composites. The proposed project studies the influence of mechanical stress on the polymersolid interphase, especially the local molecular dynamics of the polymer chains in bulk and interface. Therefore, we use a combination of different methods: First, the mechanical properties are characterised by linear rheology and their non-linear extension, e.g. Fouriertransform-Rheology. Then the influence of nonlinear stress on the interface is characterised with Rheo-SAXS, and the local dynamic properties, especially the differences between the mobility in bulk and in the interface, are examined with NMR-relaxometry. One important point of the project is the use and the optimization of new, self developed combined instrumentations (Rheo-NMR and Rheo-SAXS) allowing simultaneous characterisation of local mobility of single monomers (≈ 0.5 nm, mainly via NMR) and local structure and ordering (mainly via Rheo-SAXS) under applied non-linear mechanical stress.