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may never overcome the effects of hysteresis and stress (see
Chapters 6 and 12). The first sentence of the reference work,
Handbook of Liquid Crystals, reads: The terms liquid crystals,
crystalline liquid, mesophase, and mesomorphous state are used
synonymously to describe a state of aggregation that exhibits a
molecular order in a size range similar to that of a crystal but
acts more or less as a viscous liquid: [2] In other words,
molecules within a liquid crystalline phase possess some
orientational order and lack positional order; furthermore, the
shape of a liquid crystalline sample is determined by the vessel in
which it is contained rather than by the orientational order of its
aggregated molecules. The authors recognized the limitations and
imprecision of this definition but, like others preceding them,
could not devise a simple and generally applicable one that is
better. Regardless, the terms 'liquid crystal' and 'mesophase'
should not be used interchangeably. As mentioned above, all liquid
crystals are mesophases, but all mesophases are not liquid
crystals. Recent studies, employing elaborate and sophisticated
analytical techniques, have permitted finer distinctions between
classical crystals and mesophases. At the same time, they have made
definitions like that from the Handbook of Liquid Crystals somewhat
obsolete for reasons other than terminology. One part of the
problem arises from the use of a combination of bulk properties
(like flow) and microscopic properties (like molecular ordering)
within the same definition.
may never overcome the effects of hysteresis and stress (see
Chapters 6 and 12). The first sentence of the reference work,
Handbook of Liquid Crystals, reads: The terms liquid crystals,
crystalline liquid, mesophase, and mesomorphous state are used
synonymously to describe a state of aggregation that exhibits a
molecular order in a size range similar to that of a crystal but
acts more or less as a viscous liquid: [2] In other words,
molecules within a liquid crystalline phase possess some
orientational order and lack positional order; furthermore, the
shape of a liquid crystalline sample is determined by the vessel in
which it is contained rather than by the orientational order of its
aggregated molecules. The authors recognized the limitations and
imprecision of this definition but, like others preceding them,
could not devise a simple and generally applicable one that is
better. Regardless, the terms 'liquid crystal' and 'mesophase'
should not be used interchangeably. As mentioned above, all liquid
crystals are mesophases, but all mesophases are not liquid
crystals. Recent studies, employing elaborate and sophisticated
analytical techniques, have permitted finer distinctions between
classical crystals and mesophases. At the same time, they have made
definitions like that from the Handbook of Liquid Crystals somewhat
obsolete for reasons other than terminology. One part of the
problem arises from the use of a combination of bulk properties
(like flow) and microscopic properties (like molecular ordering)
within the same definition.
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