Structure and Dynamics of the Exfoliation of Layered Nanosilicates in 'Liquid Rubber'

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The clay montmorillonite (MMT) is a frequently used compound for medical applications and industrial production of improved polymeric materials (composite materials). Global production ranges in mega-tons per year. The clay consists of stacks of thin aluminium silicates. By evenly distributing these sheets within the polymer matrix, enhanced mechanical properties can be archived. Mixing of MMT with "liquid rubber", low molecular end-functionalized poly(butadiene), results in a fast gelation and a subsequent delamination of the stacks. Whereas the structure during this process is not known yet, the product of the modulus and the characteristic relaxation time, which shows the dimension of a viscosity, stays constant during this whole delamination process. To the knowledge of the author, this unique behaviour was not observed for other materials and may indicate a potentially new class of materials. Organically modified MMT and laponite (as a model system) will be investigated by scattering measurements (static and dynamic light scattering, X-ray and neutron scattering) and complemented by rheological methods in order to examine the system. Optimum properties are found at intermediate clay loadings. Understanding of structure and exfoliation mechanism is the basis for increasing the MMT content in composites to higher values without the loss of the improved material properties of the composite.