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Static and Shear Dependent Phase Behavior of Polydiene Elastomer Blends
Views：982    Date：2014/1/23
Prof. Charles C. Han
Joint Laboratory of Polymer Science and Materials Institute of Chemistry, Chinese Academy of Sciences,USA
Title:Static and Shear Dependent Phase Behavior of Polydiene Elastomer Blends
  

Abstract:

Polybutadiene (PB) and polyisoprene (PI) are technologically important elastomers. However, due to the polymerization chemistry, almost all the synthetic PB’s and PI’s are copolymers due to the inevitable co-existence of both 1,4 and vinyl (1,2 for Butadiene and 3,4 for Isoprene) additions in the polymerization processes except the real natural PI rubber. This has made it very important and meanwhile difficult to understand the equilibrium and kinetic phase behavior of the blends of these elastomers, especially under the shear fields. In this presentation, the technique of Small Angle Neutron Scattering will be used to demonstrate the study of the pair interaction parameters between all the possible co-monomer pairs on the basis of the Flory-Huggins mean-field theory and the Random Phase Approximation of de Gennes. Also, the kinetics of phase separation under oscillatory shear flow and the shear induced mixing (critical temperature shift) of a polymer blend of low vinyl PB and low vinyl PI (LPI) will be presented. The underlying physics has been investigated for the storage modulus at various temperatures and shear frequencies as the system passes through the binodal and the spinodal phase boundary lines. We considered the nucleation mechanism, spinodal fluctuations, shear induced mixing and rheological models in the interpretation of these interesting phenomena. Also, with proper theoretical analysis, proper procedures of obtaining bimodal and spinodal points will be discussed.

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Biography:

Charles C. Han received his B.S. degree in Chemical Engineering from the National Taiwan University in 1966. He received his Ph.D. degree in Physical Chemistry from the University of Wisconsin, Madison in 1973. He joint the National Bureau of Standards (changed to National Institute of Standards and Technology) in 1974. He was a research scientist, then group leader for the polymer blends group and later the multiphase materials group. He was elected as the NIST fellow in 1995. He joint the Institute of Chemistry, the Chinese Academy of Sciences in 2002 as the chief scientist and the director for the joint laboratory of polymer science and materials. His research interests include light scattering, dynamic light scattering, small angle neutron scattering and small angle X-ray scattering in polymer research, order-disorder transition and pattern formation of block copolymers, equilibrium phase behavior and kinetics of spinodal decomposition of polymer mixtures and crystallization behaviors, shear dependence of the static and kinetic phase behavior of polymer mixtures and its application in polymer processing, and more recently on the in-reactor alloying of polyolefins with compound catalyst. He has won many awards and prizes, include Dillon Medal of American Physical Society, Humboldt Senior Research Award from Alexander von Humboldt Foundation, the High Polymer Physics Prize, American Physical Society, and the International Award of The Society of Polymers, Japan. He has published more than 400 research papers, and authored or co-authored 27 books, with a H-index of 46. He also has more than 30 US and/or Chinese patents which have been approved or disclosed.