Molecular orientation in quenched channel flow of a flow aligning main chain thermotropic liquid crystalline polymer

N. Vaish; D. K. Cinader; W. R. Burghardt; W. Zhou; J. A. Kornfield

doi:10.1016/S0032-3861(01)00575-4

Molecular orientation in quenched channel flow of a flow aligning main chain thermotropic liquid crystalline polymer

N. Vaish, D. K. Cinader, W. R. Burghardt^*, W. Zhou, J. A. Kornfield

^*Corresponding author for this work

Chemical and Biological Engineering

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

We report measurements of molecular orientation in solid specimens of a main-chain thermotropic liquid crystalline polymer (LCP) that were quenched from mixed shear-extensional channel flows. The polymer under investigation is a random copolyether with mesogens separated by flexible hydrocarbon spacers. This polymer is known to exhibit 'flow aligning' dynamics under slow shear flow. Experiments were designed to preserve the molecular orientation state, representative of steady, isothermal channel flow in the solid samples, so that comparisons could be made against in situ channel flow measurements on other main chain thermotropes without flexible spacers, including a commercial fully aromatic copolyster. In the flow aligning material, little change in orientation was found in slit-contraction flows, and only modest drops in orientation were found in slit-expansion flow. This contrasts strongly with data on commercial LCPs, suggesting that these materials may be of the 'tumbling' type.

Original language	English (US)
Pages (from-to)	10147-10153
Number of pages	7
Journal	Polymer
Volume	42
Issue number	26
DOIs	https://doi.org/10.1016/S0032-3861(01)00575-4
State	Published - Sep 26 2001

Keywords

Director tumbling
Injection molding
Liquid crystalline polymer

ASJC Scopus subject areas

Organic Chemistry
Polymers and Plastics
Materials Chemistry

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10.1016/S0032-3861(01)00575-4

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title = "Molecular orientation in quenched channel flow of a flow aligning main chain thermotropic liquid crystalline polymer",

abstract = "We report measurements of molecular orientation in solid specimens of a main-chain thermotropic liquid crystalline polymer (LCP) that were quenched from mixed shear-extensional channel flows. The polymer under investigation is a random copolyether with mesogens separated by flexible hydrocarbon spacers. This polymer is known to exhibit 'flow aligning' dynamics under slow shear flow. Experiments were designed to preserve the molecular orientation state, representative of steady, isothermal channel flow in the solid samples, so that comparisons could be made against in situ channel flow measurements on other main chain thermotropes without flexible spacers, including a commercial fully aromatic copolyster. In the flow aligning material, little change in orientation was found in slit-contraction flows, and only modest drops in orientation were found in slit-expansion flow. This contrasts strongly with data on commercial LCPs, suggesting that these materials may be of the 'tumbling' type.",

keywords = "Director tumbling, Injection molding, Liquid crystalline polymer",

author = "N. Vaish and Cinader, {D. K.} and Burghardt, {W. R.} and W. Zhou and Kornfield, {J. A.}",

note = "Funding Information: We acknowledge financial support from an AFOSR MURI on Liquid Crystals, Grant F49620-97. X-ray experiments were conducted at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) Synchrotron Research Center located at Sector 5 of the Advanced Photon Source. DND-CAT is supported by the E.I. DuPont de Nemours and Co., the Dow Chemical Company, and the National Science Foundation through Grant DMR-9304725 and the State of Illinois through the Department of Commerce and the Board of Higher Education Grant IBHE HECA NWU 96. Use of the Advanced Photon Source was supported by the US Department of Energy, Basic Energy Sciences, Office of Energy Research under Contract no. W-31-102-Eng-38. ",

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AU - Vaish, N.

AU - Cinader, D. K.

AU - Burghardt, W. R.

AU - Zhou, W.

AU - Kornfield, J. A.

N1 - Funding Information: We acknowledge financial support from an AFOSR MURI on Liquid Crystals, Grant F49620-97. X-ray experiments were conducted at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) Synchrotron Research Center located at Sector 5 of the Advanced Photon Source. DND-CAT is supported by the E.I. DuPont de Nemours and Co., the Dow Chemical Company, and the National Science Foundation through Grant DMR-9304725 and the State of Illinois through the Department of Commerce and the Board of Higher Education Grant IBHE HECA NWU 96. Use of the Advanced Photon Source was supported by the US Department of Energy, Basic Energy Sciences, Office of Energy Research under Contract no. W-31-102-Eng-38.

PY - 2001/9/26

Y1 - 2001/9/26

N2 - We report measurements of molecular orientation in solid specimens of a main-chain thermotropic liquid crystalline polymer (LCP) that were quenched from mixed shear-extensional channel flows. The polymer under investigation is a random copolyether with mesogens separated by flexible hydrocarbon spacers. This polymer is known to exhibit 'flow aligning' dynamics under slow shear flow. Experiments were designed to preserve the molecular orientation state, representative of steady, isothermal channel flow in the solid samples, so that comparisons could be made against in situ channel flow measurements on other main chain thermotropes without flexible spacers, including a commercial fully aromatic copolyster. In the flow aligning material, little change in orientation was found in slit-contraction flows, and only modest drops in orientation were found in slit-expansion flow. This contrasts strongly with data on commercial LCPs, suggesting that these materials may be of the 'tumbling' type.

AB - We report measurements of molecular orientation in solid specimens of a main-chain thermotropic liquid crystalline polymer (LCP) that were quenched from mixed shear-extensional channel flows. The polymer under investigation is a random copolyether with mesogens separated by flexible hydrocarbon spacers. This polymer is known to exhibit 'flow aligning' dynamics under slow shear flow. Experiments were designed to preserve the molecular orientation state, representative of steady, isothermal channel flow in the solid samples, so that comparisons could be made against in situ channel flow measurements on other main chain thermotropes without flexible spacers, including a commercial fully aromatic copolyster. In the flow aligning material, little change in orientation was found in slit-contraction flows, and only modest drops in orientation were found in slit-expansion flow. This contrasts strongly with data on commercial LCPs, suggesting that these materials may be of the 'tumbling' type.

KW - Director tumbling

KW - Injection molding

KW - Liquid crystalline polymer

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Molecular orientation in quenched channel flow of a flow aligning main chain thermotropic liquid crystalline polymer

Abstract

Keywords

ASJC Scopus subject areas

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