Allomorphs of native crystalline cellulose I evaluated by two equatorial d-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 I-alpha/I-beta (triclinic/monoclinic) ratio of the cellulose samples. We investigated various native celluloses by X-ray diffractometry; and discriminant analysis was carried out using two equatorial d-spacings: 0.59-0.62 nm (d(1)) and 0.52-0.55 nm (d(2)). 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 = 1693d(1) - 902d(2) - 549, where Z > 0 indicates the algal-bacterial (I-alpha-rich) type and Z > 0 indicates the cotton-ramie (I-alpha- dominant) type. Another X-ray diffraction study of hydrothermally treated Cladophora cellulose revealed the relation between the d-spacings (d(1), d(2)) and the I-alpha/I-beta ratio. A calibrating equation by which the I-alpha/I-beta ratio was estimated from the two parameters, d(1) and d(2), was then prepared. In the case of relatively highly crystalline native celluloses, it was found that the I-alpha/I-beta ratio is easily determined by applying the two parameters in the equation.