Effect of Moisture on the Orientation Birefringence of Cellulose Esters

Abd Manaf, Mohd Edeerozey and Tsuji, Manami and Nobukawa, Shogo and Yamaguchi, Masayuki (2011) Effect of Moisture on the Orientation Birefringence of Cellulose Esters. Polymers, 3. pp. 955-966. ISSN 2073-4360

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Orientation birefringence and its wavelength dispersion are studied for hot-drawn films of cellulose esters such as cellulose triacetate (CTA), cellulose diacetate (CDA), and cellulose acetate propionate (CAP) exposed to three different humidities of environments. Hot-drawn CTA films show negative birefringence that decreases with increasing wavelength. On the other hand, CDA and CAP films show positive birefringence that increases with increasing wavelength, i.e., the so-called extraordinary wavelength dispersion of birefringence. Upon exposure to high humidity environment, the orientation birefringence of CDA and CAP decreases. The decrease is prominent for the samples containing a large amount of water. CTA, however, shows an increase in magnitude of its negative orientation birefringence with increasing moisture content. The results can be explained by the increase of the polarizability anisotropy perpendicular to the stretching direction in the cellulose esters. It is found from ATR-FTIR measurements that hydrogen bonds are formed between carbonyl groups of cellulose esters and water molecules. Considering that orientation birefringence of cellulose esters is determined mainly by ester groups, the formation of hydrogen bonds contributes to the polarizability anisotropy, thus affecting the orientation birefringence.

Item Type: Article
Uncontrolled Keywords: birefringence, cellulose ester, moisture content, optical film
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Faculty of Manufacturing Engineering > Department of Engineering Materials
Date Deposited: 08 Apr 2013 03:52
Last Modified: 14 Feb 2022 14:38
URI: http://eprints.utem.edu.my/id/eprint/7081
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