Abstract:

Rubbers show a unique behavior of elasticity coming from a greater contribution of entropy rather than internal energy due to their coil-like molecular architectures and conformations. Almost all rubbers are being used for various applications, notably tires components, in the forms of reinforced compounds with various fillers such as carbon blacks and silicas. The reinforcing mechanisms of conventional micro-sized fillers have been suggested extensively. They can be classified as 1) hydrodynamic interaction, 2) rubber-filler interaction, and 3) filler-filler interaction. Recently, many attempts have been made for reinforcing rubbers with nano-sized fillers including layered clays, carbon nanotubes, and graphenes etc. Relatively little focus has been given to answer the questions: “Are the reinforcing mechanisms of nano-sized fillers similar with those for micro-sized fillers?” and “Is there any difference in reinforcing mechanisms among nano-sized fillers depending on either shape or composition ?”. We will give some representative reinforcing behaviors of layered clays and ionic clusters to rubbers along with some plausible reasons. Then, we will move our discussion to some extraordinary behaviors of carbon nanotubes reinforcement with a well-designed experimental set-up, and then it will be compared with conventional carbon blacks. Finally, we will give some modeling result to explain the difference of reinforcing behaviors between carbon nanotubes and carbon blacks in our experimental observations.

Keywords: rubber;reinforcing;clay;ionic clusters,caron nanotubes;modeling

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Biography:

Changwoon Nah is Professor of Department of Polymer-Nano Science and Technology at Chonbuk National University since 1999, and he is now serving as the department head. Before joining the university, he had worked for the Kumho Tire Company as a senior research fellow at Research and Development Center (1985~1998). His recent research interests are 1) Electro-active polymers including dielectric elastomers for actuators and generators, 2) Nano-fibrous membranes for batteries and solar cells, and 3) Polymer nanocomposites for various applications including gaskets for fuel cells stacks. He published more than 130 peer-reviewed papers and book chapters on the mechanical properties of rubbers and plastic materials. He received BS and MS from Department of Chemical Engineering at Ajou University, Korea in 1984 and 1986. He received his PhD from Department of Polymer Engineering at The University of Akron, USA in 1995.