Effect of acetylation site on orientation birefringence of cellulose triacetate

Abstract

The effect of a substitution site on orientation birefringence for cellulose triacetate (CTA) was investigated by the addition of xylan ester. Since CTA has three substitution sites (C-2, C-3, and C-6) while xylan ester has two substitution sites (C-2 and C-3), the change of birefringence by xylan acetate (XylAc) is attributed to the contribution of the C-6 acetyl group. Dynamic mechanical analysis and thermal measurements showed a single glass transition peak, indicating that XylAc is miscible with CTA at any compositions. The orientation birefringence (Dn) of CTA/XylAc films stretched beyond the glass transition temperature increased with increasing the XylAc content. The result for the stretched film suggested that the contribution of acetyl group in the C-2 and C-3 sites to Dn is positive while that in the C-6 is negative. The negative sign for the C-6 site is in agreement with the result simulated by using the molecular dynamics method. In addition, Dn of CTA films containing xylan propionate (or butyrate) indicated that the propionyl and butyryl groups in the C-2 and C-3 sites show positive birefringence similar to the acetyl group.

Effect of propionyl group on birefringence and wavelength dispersion of propionylated cellulose acetate optical compensation films

“…Compared with TAC, CA has more residual substitution sites, which is more suitable for chemical modi cation with different substitution degrees. The propionyl group will be selected as the modi cation group because the propionyl group can provide positive birefringence and inverse wavelength dispersion (Yamaguchi et al 2009a(Yamaguchi et al , 2012Nobukawa et al 2015Nobukawa et al , 2017, both of which are opposite to the acetyl group. Theoretically, the combination of the above two groups can prepare the compensation lm meeting the requirements of VA-LCD.…”

Miscible Transparent Polymethylmethacrylate/Cellulose Acetate Propionate Blend: Optical, Morphological, and Thermomechanical Properties

“…Recent research has focused on the use of biodegradable materials such as cellulose esters in the formation of layers or blends to handle some of their polymer optical, mechanical, and thermal properties (Nobukawa et al 2014;Park et al 2014;Kunthadong et al 2015;Nobukawa et al 2015). Cellulose acetate propionate (CAP) is an amorphous, transparent, and thermally stable polymer belonging to the cellulose ester family that has attracted attention from scientists because of its biocompatibility and properties intermediate between cellulose acetate and cellulose acetate butyrate.…”