Thermal, mechanical and electrical properties of highly loaded CNT-epoxy composites - A model for the electric conductivity

Based on their extraordinary mechanical, electrical and thermal properties carbon nanotubes (CNT) are attributed as high potential filler material for polymer matrices. Besides the CNT material and functionalization, the properties of the polymer matrix, stabilization additives as well as the production process have a significant influence on the maximum CNT content and the resultant composite properties. Adapted from a modification of commonly used solvent based approaches a production process for high loaded epoxy based composites is presented in this study. In this process high loadings of up to 80 wt% CNTs are embedded in the epoxy composite matrix. The resultant mechanical, electrical and thermal properties are investigated for various CNT types, CNT modification, stabilization and loadings. Moreover, a model for the electric conductivity of CNT reinforced composites above the percolation threshold is presented. This model describes the electric conductivity as a function of the composite structure including CNT content as well as a theoretical value for the number of contacts within such a composite network.