Structural elucidation of network effects in highly filled polymers

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The modification of existing technical thermoplasts with active fillers, functional fillers or inactive fillers is a cost effective and commonly used way. Blending of different polymers with fillers is an essential way to develop new polymers in modern polymer processing, as well. Goal of the modification is always the change of physical properties. In this way active fillers are able to enhance the mechanical properties and elastic fillers are able to enhance the elongation behavior. Conductive fillers improve for example the electrical and/or the thermal conductivity of polymers. A high homogeneity of all modifiers in the polymers is very important in order to achieve the desired performance. Additionally, the modifiers should only change negligibly the flowability of the unmodified polymer due to changes in the processability. Up to now the common knowledge is, that the yielding behavior at low shear rates of highly filled polymers is caused by particle networks. The literature talks often about particle-particle interactions, which have not been investigated by images. Some sources report images, but cannot proof a particle-particle network. The aim of this research project is the gain comprehensive knowledge of the three-dimensional network structures of different fillers in various polymers. If - as has been described in the literature - some of these three-dimensional networks are refuted figuratively, although the yielding behavior occurs, the hypothesis of the applicant to should be investigated intensively. These studies are focused on the one hand distinguish the effects of different pairings of polar and nonpolar partners of matrix and secondly targeted lower molecular weights (shorter molecular chains) are used to reduce the influence of the particles environment. Thus, initially, various material-additive combinations with different selected additive geometries are combined by a compounding process. At low shear rates the yield behavior should occur and can be achieved with a rheometer. In this state, the samples are cooled and will be morphologically analyzed using various methods in all three dimensions. Quantification of structures depending on the deformation size can be quantified by the fractal dimension, as well. For this purpose the non-destructive testing is used in addition to extend the structural analysis. The characterization of the particulate structure by means of nondestructive testing even has the potential to be used as an online monitoring tool in industrial applications.