Abstract
This paper presents x-ray diffraction studies on acid-hydrolyzed and ball-milled celluloses which are, respectively, used as "standards" of crystalline and amorphous cellu lose in crystallinity determinations of other samples. It is shown that the observed x-ray powder diffractograms of cellulose I and II standards, when compared with calcu lated diffraction profiles of cellulose crystallites with certain plausible dimensions, clearly indicate the presence of small amounts of imperfectly ordered material in both "standards." Data on some physical properties of these standards also support this finding. In the case of ball-milled cellulose, it has been shown that above a scattering angle of 43° with copper radiation, the intensity of scattering can be completely accounted for in terms of independent scattering from individual β-anhydroglucosidic units. Below this angle, the diffuse maximum in the scattering curve appears to be due to the repeat distance within a cellulose chain. Thus, ball-milled cellulose is a satisfactory amorphous standard.
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