A NEW LOOK AT THE CHAIN POLARITY PROBLEM OF CELLULOSE

Abstract

It is suggested that the chain polarity of native cellulose, cellulose I, is preserved in the course of the transformation to cellulose II by mercerization as a resonable interpretation of following results. The selective uniplanar orientation of (1_??_0) plane of original bacterial cellulose is maintained during and after mercerization to provide cellulose 11 pattern resulted in the preferential orientation. Furthermore, when the air-dried or never-dried spherulite of bacterial cellulose was immersed in 18% NaOH, the Maltese cross pattern and the color correlation are the same as those of the original. There are several other evidences for the same polarity of cellulose 1 and II. It was proved that cellulose triacetate (CTA) I can be formed by the heterogeneous acetylation of cellulose II as well as cellulose I when the swelling in the pretreatment media is low. It seems that parallel arrangement is not necessarily correct structure of CTA I. It is possible to transform CTA I to CTA II without any dissolving process but by a comparatively simple treatment with superheated steam. These mean that CTA I and CTA II have the same polarity in their crystal structures. The transformation of cellulose I to cellulose II through cellulose III_I which is hydrolyzed by 20N H₂SO₄ without disolution has been newly observed in the present study. Completely amorphous wood pulp decrystallized by the mechanical milling is recrystallized to cellulose II with water or 1% NaOH. It seems to be difficult to reverse the chain or to attain antiparallel arrangement from parallel one during the mechanical milling. On the other hand, the chain polarity problem has been solved by the direct TEM observation of LODP cellulose reacted with hydrazine. Characteristic microfibril of the LODP cellulose are observed with uniform width and length of about 200A and 2000A, respectively. In contrast with this, the reacted microfibril is long but has irregular pattern in shape. The possibility of antiparallel arrangement in ramie cellulose has been directly proved by the microphotographs.