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Title: | Molecular orientation and optical anisotropy in drawn films of cellulose diacetate-graft-PLLA: comparative investigation with poly(vinyl acetate-co-vinyl alcohol)-graft-PLLA |
Authors: | Unohara, Takeshi Teramoto, Yoshikuni ![]() ![]() ![]() Nishio, Yoshiyuki ![]() ![]() |
Author's alias: | 西尾, 嘉之 |
Keywords: | Cellulose acetate Poly(vinyl acetate-co-vinyl alcohol) Poly(L-lactide) Graft copolymer Molecular orientation Optical anisotropy |
Issue Date: | Jun-2011 |
Publisher: | Springer Science+Business Media B.V. |
Journal title: | Cellulose |
Volume: | 18 |
Issue: | 3 |
Start page: | 539 |
End page: | 553 |
Abstract: | Cellulose diacetate-graft-poly(L-lactide) (CDA-g-PLLA) and poly(vinyl acetate-co-vinyl alcohol)-graft-PLLA (P(VAc-co-VOH)-g-PLLA) were synthesized over a range of compositions, by ring-opening copolymerization of L-lactide at the original hydroxyl positions of the respective trunk polymers, CDA (acetyl DS = 2.15) and P(VAc-co-VOH)-g-PLLA (VAc = 64.2 mol%). All the products of both graft copolymer series were non-crystallizable and their solution-cast films showed no domain segregation of the two components that constituted the trunk and side-chains. A comparative study on the molecular orientation and optical anisotropy induced by uniaxial stretching of film samples was undertaken for the two copolymer series with various side-chain lengths. Overall behaviour of the orientation was estimated from the statistical second (<cos2 ω>) and fourth (<cos4 ω>) moments obtained by a fluorescence polarization method using a rod-like probe of ~2.5 nm. Upon stretching, any film of both series imparted a positive orientation function, i.e., f = (3 <cos2 ω> − 1)/2 > 0, which increased with the extent of deformation. The degree of molecular orientation was higher in the CDA-graft series with a semi-rigid trunk, and, in both series, it declined monotonically with increasing content of the PLLA side-chain. With regard to the optical anisotropy, CDA-g-PLLA films always exhibited a positive birefringence (Δn > 0) upon stretching, while drawn films of P(VAc-co-VOH)-g-PLLA displayed a negative one. This contrast in polarity reflects a difference in the intrinsic birefringence between the two trunk polymers. Of interest was the finding of a discontinuous change in Δn value with copolymer composition (PLLA content) for the respective graft series, when compared at a given stage of elongation of the films. Discussion took into consideration the locally different orientation manners of the attached PLLA chain segments. |
Rights: | The final publication is available at www.springerlink.com This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。 |
URI: | http://hdl.handle.net/2433/141838 |
DOI(Published Version): | 10.1007/s10570-011-9508-0 |
Appears in Collections: | Journal Articles |

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