An X-Ray Diffraction Study of the Crystalline to Amorphous Phase Change in Cellulose During High-Energy Dry Ball Milling

Abstract

In methods used widely for determining "crystallinity" of cellulose substrates by X-ray wide angle diffraction the scattering characteristics of truly "amorphous" cellulose is needed. So far, such scattering curves have not been available. It was the aim of this study to arrive at an experimentally determined scattering curve of amorphous cellulose. For this purpose, two cellulose samples (a pine wood pulp and a microcrystalline powder) were ball milled in a high-energy equipment in order to destroy the crystalline structure. The structural changes in the cellulose samples and the kinetics of amorphization were followed by taking X-ray diffractograms. After 30 min of milling, no more change in the structure could be observed and the diffraction curve of amorphous cellulose with two diffuse maxima at spacings of 0.427 nm (strong) and 0.247 nm (weak) was obtained. The amorphization was found to follow a first order kinetics, the rate constant of k = (0.0033 ± 0.0004) s" 1 holding for both samples. However, while the amorphization of the microcrystalline cellulose started immediately, with the wood pulp sample an induction period of about 300 seconds was observed, which is probably due to residual morphological structures present in this sample.

Cellulose I crystallinity determination using FT–Raman spectroscopy: univariate and multivariate methods

“…3j). Further support comes from the literature (Teeaar et al 1987;Hulleman et al 1994;Stubičar et al 1998;Isogai et al 2009) wherein the peak position in completely amorphous cellulose is reported to be 20-21°and not 18°(as Segal et al 1959 reported). Although not clear why this is the case, the finding of the higher 2h value may possibly result from the Fig.…”

“…3;Hulleman et al 1994, Fig. 1; Stubičar et al 1998) it was concluded that the 120-min milled sample was completely amorphous. This conclusion was further supported by the great similarity between the band profiles of 357 and 380 cm -1 of 60-120 min milled samples (Fig.…”

The hygroscopic power of amorphous cellulose: A modeling study

“…On the other hand, water, which is free to penetrate the amorphous domains, strongly affects the physico-chemical properties of such a phase (Mihranyan, Llagostera, Karmhag, Stromme, & Ek, 2004;Mohan et al, 2012;Stromme, Mihranyan, Ek, & Niklasson, 2003). All the key interactions between water and cellulose are thus concentrated essentially within the cellulose amorphous phase (Princi, Vicini, Pedemonte, Arrighi, & McEwen, 2005 Completely amorphous samples of cellulose are not natural but they can be produced following different methods (Ciolacu, Ciolacu, & Popa, 2011), including ball milling (Hermans & Weidinger, 1946;Shimura, Nishioka, Kano, Koda, & Nishio, 2014;Stubicar et al, 1998), deacetylation of cellulose acetate under non aqueous conditions (Manley, 1963) and regeneration of cellulose solutions into non aqueous media (Atalla, Ellis, & Schroeder, 1984;Schroeder, Gentile, & Atalla, 1986). Whereas many of these amorphous celluloses will readily recrystallize in water (Ciesla, Rahier, & Zakrzewska-Trznadel, 2004;Hatakeyama & Hatakeyama, 1981Hatakeyama, Nakamura, & Hatakeyama, 2000;Kimura, Hatakeyama, & Nakano, 1974;Paes et al, 2010), some specimens remain amorphous under hydrated conditions (Isogai & Atalla, 1991;Isogai, Akishima, Onabe, Usuda, & Atalla, 1989) and among these, some of them display remarkable swelling properties .…”

Microstructural evolution of some MgO–TiO2 and MgO–Al2O3 powder mixtures during high-energy ball milling and post-annealing studied by X-ray diffraction

“…Since the discovery in 1983 that even amorphous alloys can be produced by these techniques [7,8], a new wave of research activity concerned with the possibilities and perspectives of this process has been unleashed. During the past decade we have published the results of our investigations regarding the structural changes in various examined systems induced by ball-mill processing [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In our and in other investigations [25][26][27][28][29] it has been established, that ball milling can facilitate many solid-state reactions, which normally occur only at elevated temperatures and/or high pressure.…”