Three-dimensional morphology analysis and finite element modeling of nano particle dispersed materials

This paper presents a three-dimensional morphology analysis technique by means of TEM tomography and finite element modeling of nano particle dispersed composite materials. The target material system in this paper is natural rubber reinforced by carbon black (CB) nano-particles. The average diameter of CB ranges from 30 to 122nm. The main feature of this paper is that the interphase named sticky hard layer between CB and free rubber is considered in detail. The Young's modulus was estimated by pulse nuclear magnetic resonance (NMR), and the thickness was obtained by measuring the volume content and moreover considering the agglomeration of CB nano-particles. The Young's modulus of the sticky hard layer was 5 to 30 times larger than that of free rubber. The relative thickness of the sticky hard layer divided by the CB diameter was found to be very influential on the overall properties of the composites, because its percolation forms the load carrying path in the composites as demonstrated by finite element analysis. These results have been supposed to be the major reason to explain the nano-particle size effect on the overall properties, which have never been understood by the classical rule of mixture.