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Electro–optic studies on polymer‐dispersed liquid crystal composite films. I. Composites of PVB–E7
Author(s) -
Kalkar A. K.,
Kunte V. V.,
Deshpande A. A.
Publication year - 1999
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19991227)74:14<3485::aid-app23>3.0.co;2-5
Subject(s) - materials science , composite material , liquid crystal , composite number , transmittance , scanning electron microscope , optical microscope , polymer , phase (matter) , polyvinyl butyral , optoelectronics , chemistry , organic chemistry
The electro‐optic performance characteristic of polymer‐dispersed liquid crystal (PDLC) composite films out of poly(vinyl butyral) (PVB) and nematic liquid crystal (E7) have been studied for a wide range of PVB–E7 composite compositions (20–70 wt % of E7). Composites were prepared by solvent casting from chloroform at room temperature. A scanning electron microscopy study showed that a E7 phase is continuously embedded in chink‐like structure of PVB matrix. Optical transmittance of the composite films (of 60 and 70 wt % loading of E7) under an alternating current (ac) electric field (0–250, V p ‐ p ) and frequency (50 Hz to 1 KHz) were measured employing HeNe laser (λ = 632.8 nm). The results indicate that the (PVB–E7) composite exhibits a memory effect. In the memory state, higher transmittance is preserved without applying voltage. The memory state can be erased and changed to the scattering Off‐state by heating the film to the clearing temperature of the liquid crystal. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3485–3491, 1999