本文发表在 rolia.net 枫下论坛Computational study of the texture formation in mesophase pitch‐based carbon fibres
Authors: Hong, Shujuan1; Chan, Philip1
Source: Liquid Crystals, Volume 33, Number 3, March 2006, pp. 295-306(12)
Publisher: Taylor and Francis Ltd
< previous article | next article > | View Table of Contents
Key: - Free content - New Content - Subscribed Content - Free Trial Content
Abstract:
This paper studies the thermal relaxation phenomena after melt‐extrusion of a rigid discotic uniaxial nematic mesophase pitch using mathematical modelling and computer simulation. The Ericksen and Landau–de Gennes continuum theories are used to investigate the structure development and texture formation across mesophase pitch‐based carbon fibres. The two‐dimensional model captures five types of transverse patterns, which match the commonly observed textures for mesophase pitch‐based carbon fibres. They are: random, zig‐zagged radial, radial, quasi‐onion and onion. These textures represent the various combinations possible from the interplay between structure (i.e. texture) development and cooling during the fibre spinning process. During the thermal relaxation after the cessation of extensional flow the discotic nematic molecules store elastic free energy decays. The distorted nematic molecular profiles reorient to release the stored elastic free energy. The difference in time scales for molecular reorientation and thermal relaxation result in different transverse textures. The rate at which the fibres are cooled is the main factor in controlling the structure development. A slow cooling rate would permit the nematic discotic molecules to reorient to a well‐developed (radial or onion) texture. The random texture is a result of rapid quenching. The numerical results are consistent with published experimental observations.
Document Type: Research article
DOI: 10.1080/02678290500242213
Affiliations: 1: Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada更多精彩文章及讨论，请光临枫下论坛 rolia.net
Authors: Hong, Shujuan1; Chan, Philip1
Source: Liquid Crystals, Volume 33, Number 3, March 2006, pp. 295-306(12)
Publisher: Taylor and Francis Ltd
< previous article | next article > | View Table of Contents
Key: - Free content - New Content - Subscribed Content - Free Trial Content
Abstract:
This paper studies the thermal relaxation phenomena after melt‐extrusion of a rigid discotic uniaxial nematic mesophase pitch using mathematical modelling and computer simulation. The Ericksen and Landau–de Gennes continuum theories are used to investigate the structure development and texture formation across mesophase pitch‐based carbon fibres. The two‐dimensional model captures five types of transverse patterns, which match the commonly observed textures for mesophase pitch‐based carbon fibres. They are: random, zig‐zagged radial, radial, quasi‐onion and onion. These textures represent the various combinations possible from the interplay between structure (i.e. texture) development and cooling during the fibre spinning process. During the thermal relaxation after the cessation of extensional flow the discotic nematic molecules store elastic free energy decays. The distorted nematic molecular profiles reorient to release the stored elastic free energy. The difference in time scales for molecular reorientation and thermal relaxation result in different transverse textures. The rate at which the fibres are cooled is the main factor in controlling the structure development. A slow cooling rate would permit the nematic discotic molecules to reorient to a well‐developed (radial or onion) texture. The random texture is a result of rapid quenching. The numerical results are consistent with published experimental observations.
Document Type: Research article
DOI: 10.1080/02678290500242213
Affiliations: 1: Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada更多精彩文章及讨论，请光临枫下论坛 rolia.net