Study of the network formation of carbon nanotubes in epoxy matrices for electrical conductivity improvement [Elektronische Ressource] / von Josef-Zoltan Lott

Study of the network formation of carbon nanotubes in epoxy matrices for electrical conductivity improvement Vom Promotionsausschuss der Technischen Universität Hamburg-Harburg zur Erlangung des akademischen Grades Doktor der Naturwissenschaften (Dr. rer. nat.) genehmigte Dissertation von Dipl.-Phys. Josef-Zoltan Lott (geb. Kovacs) aus Temeschburg, Rumänien 2009 st1 member of committee: Prof. Dr. rer. nat. Wolfgang Bauhofer nd2 member of committee: Prof. Dr.-Ing. Karl Schulte thDate of examination: August 10 , 2009 ii For Christina iii iv Abstract This thesis analyses the network formation of CNT in epoxy matrices using scanning electron microscopic (SEM), electrical, Raman spectroscopic and rheological techniques. Investigations are focused on the improvement of the electrical properties of the CNT/epoxy composites. A non-destructive method called voltage (or charge) contrast SEM was developed for determining the real CNT shapes and distributions in a composite over several length scales. This knowledge is crucial for the interpretation of all upcoming experiments. Conductivity measurements revealed two percolation thresholds, the lower one attributed to a kinetic and the higher one to a statistic network formation process.