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Full-Text Articles in Engineering

Thermodynamic Behavior Of Poly(Cyclohexylethylene) In Polyolefin Diblock Copolymers, Eric W. Cochran, Frank S. Bates Aug 2002

Thermodynamic Behavior Of Poly(Cyclohexylethylene) In Polyolefin Diblock Copolymers, Eric W. Cochran, Frank S. Bates

Eric W. Cochran

We report the temperature dependence of the Flory-Huggins interaction parameter for three symmetric diblock copolymer systems containing poly(cyclohexylethylene) (PCHE): poly(cyclohexylethylene-b-ethylene) (CE), poly(cyclohexylethylene-b-ethylethylene) (CEE), and poly(cyclohexylethylene-b-ethylenepropylene) (CP). Order-disorder transition temperatures (TODT) were determined using dynamic mechanical spectroscopy and interpreted with mean-field theory, (χN)ODT = 10.5, leading to well-defined expressions for χ(T). These results have been analyzed in the context of solubility parameter (δ) theory resulting in a unique parameter δC that describes the interactions in CE, CP, and CEE, where δC < δEE < δP < δE with (δE - δC) ≈ 1.6 MPa1/2 at 500 K. In contrast to the predictions of group contribution theory, this indicates that δC is in surprisingly close proximity to the solubility parameter for poly(dimethylsiloxane).


Beta Zeolite Supported On A Macroscopic Pre-Shaped Sic As A High Performance Catalyst For Liquid-Phase Benzoylation, G. Wine, Jean-Philippe Tessonnier, C. Pham-Huu, M. J. Ledoux Jan 2002

Beta Zeolite Supported On A Macroscopic Pre-Shaped Sic As A High Performance Catalyst For Liquid-Phase Benzoylation, G. Wine, Jean-Philippe Tessonnier, C. Pham-Huu, M. J. Ledoux

Jean-Philippe Tessonnier

Preparation and characterisation of a highly active and stable beta zeolite supported on a pre-shaped silicon carbide catalyst for the benzoylation reaction in liquid phase.