Water vapor transport in liquid crystalline and non-liquid crystalline epoxies

This paper presents a comparison of moisture permeation in liquid crystalline and non-liquid crystalline epoxy systems. The permeability is obtained using a dynamic method. It is found that diffusion in both epoxy systems is Fickian. The liquid crystalline epoxy network exhibits higher barrier prope...

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Bibliographic Details
Published in:Journal of materials science 2004-05, Vol.39 (10), p.3413-3423
Main Authors: Feng, Jianxun, Berger, K. R, Douglas, E. P
Format: Article
Language:English
Subjects:
Applied sciences
Crystal structure
Crystallinity
Diffusion coefficient
diffusivity
epoxides
Exact sciences and technology
Hydrogen bonding
Liquid crystals
liquids
Materials science
Mesophase
Miscellaneous
Moisture
Morphology
Organic polymers
Penetration
Permeability
Physicochemistry of polymers
Properties and characterization
solubility
Stoichiometry
Transport
Water vapor
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Description
Summary:This paper presents a comparison of moisture permeation in liquid crystalline and non-liquid crystalline epoxy systems. The permeability is obtained using a dynamic method. It is found that diffusion in both epoxy systems is Fickian. The liquid crystalline epoxy network exhibits higher barrier properties to moisture transport than the conventional epoxy network. The efficient chain packing of the smectic mesophase of the liquid crystalline epoxy is the main factor for this difference. The stoichiometry has a large effect on the moisture permeation. The diffusion coefficient decreases monotonically with increasing amine/epoxide functional ratio. The permeability (P) and solubility coefficient (S) reach a minimum for a functional ratio of one. The results are described on the basis of hydrogen bonding of water to the epoxy network and the two phase morphology of cured epoxies.
ISSN:0022-2461
1573-4803
DOI:10.1023/B:JMSC.0000026944.85440.f3