The mechanical and magnetic alignment of liquid crystalline epoxy thermosets

Autor: David W. Wang, Christopher K. Ober, George G. Barclay, Konstantinos I. Papathomas, S. G. McNamee
Rok vydání: 1992
Předmět:
Zdroj: Journal of Polymer Science Part A: Polymer Chemistry. 30:1845-1853
ISSN: 1099-0518
0887-624X
DOI: 10.1002/pola.1992.080300907
Popis: The processing of a new series of liquid crystalline (LC) epoxy networks was evaluated. Above the glass transition temperature, the low crosslink density networks could be mechanically aligned. The mechanically oriented networks readily lost orientation upon heating. Highly anisotropic liquid crystalline (LC) epoxy networks were also prepared by aligning the mesophase of the prepolymer during the curing process under the influence of a magnetic field. Orientation parameters (f) of 0.13 to 0.57 were achieved by these processes as determined by x-ray diffraction analysis. The ability of the magnetically aligned networks to retain their orientation above the glass transition temperature was determined by time-resolved x-ray diffraction. The stability of the alignment of these networks was found to depend on crosslink density. The effect of the anisotropy of these networks was investigated by measuring the coefficient of thermal expansion (CTE). In the aligned networks, there was a substantial reduction in CTE parallel to the direction of the applied field compared to the randomly oriented networks. © 1992 John Wiley & Sons, Inc.
Databáze: OpenAIRE
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