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Key Characteristics Orientation Defect density Anchoring. Computational and Topological Modeling of Mesophase Carbon Composites. Alejandro D. Rey, Dept. of Chemical Engineering, McGill University, Montreal, Quebec, Canada H3A2B2.
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Key Characteristics • Orientation • Defect density • Anchoring Computational and Topological Modeling of Mesophase Carbon Composites Alejandro D. Rey, Dept. of Chemical Engineering, McGill University, Montreal, Quebec, Canada H3A2B2 Textures in mesophase pitch carbon/carbon fiber composites are a function of : (1) fiber arrangements, (2) processing flows , and (3) wetting and interfacial anchoring. Mesophase Pitch: polycyclic aromatics with a viscoelastic anisotropic discotic nematic phase; n is the average orientation. C/C composites : carbon fibers randomly dispersed in a mesophase pitch are an example of anisotropic colloids. Inserting fibers into a liquid crystal creates a texture; the specific textural features depend on the topology of the fiber arranegement (see 1). 1. Fiber arrangements (topology) 2. Liquid Crystal Coating Flows (collaboration with M. Srinivasarao (Georgia Tech) Soft Matter 5, 2277, 2009)) 3. Wetting and Anchoring on Fiber Bundles L:elastic constant S:order parameter rf:fiber radius gLC:inter. tensiom Anisotropic fluids have cross couplings. Shear deformation creates extensional stress! Theory shows that the defect charge around N fibers is –(N-2)/2. Liquid crystals always wet fiber bundles. The critical spreading parameter is larger for LCs than for isotropic fluids.
