Allomorphs of native crystalline cellulose I evaluated by two equatoriald-spacings

The aim of this study was to develop a facile method for categorizing native celluloses as the algal-bacterial type or the cotton-ramie type and for estimating the Iα/Iβ (triclinic/monoclinic) ratio of the cellulose samples. We investigated various native celluloses by X-ray diffractometry; and discriminant analysis was carried out using two equatoriald-spacings: 0.59–0.62 nm (d1) and 0.52–0.55 nm (d2). All of the samples were classified into the two groups without error. The function used to discriminate between the two groups is represented as:Z=1693d1 — 902d2 — 549, whereZ>0 indicates the algal-bacterial (Iα-rich) type andZ<0 indicates the cotton-ramie (Iβ-dominant) type. Another X-ray diffraction study of hydrothermally treatedCladophora cellulose revealed the relation between thed-spacings (d1,d2) and the Iα/Iβ ratio. A calibrating equation by which the Iα/Iβ ratio was estimated from the two parameters,d1 andd2, was then prepared. In the case of relatively highly crystalline native celluloses, it was found that the Iα/Iβ ratio is easily determined by applying the two parameters in the equation.