title: The effect of ball milling and rehydration on powdered mixtures of hydrocolloids.
abstract: In many applications, particularly in food related work, it is assumed that ball milling merely serves as a means of reducing crystallinity by the steady attrition of crystals. In this work mixtures of cellulose with other biopolymers have been co-ball milled in the dry state typically at moisture contents of <12% (w/w) and the effects of recrystallizing these mixtures studied. We have found that recystallizing the mixtures under a humid (97%RH) atmosphere increases the crystallinity of the cellulose fraction in a fashion governed by the other hydrocolloid present in the mixture. Some of the measured effects occur during ball milling of the dry powders. A relative method of fitting mixtures of type I and type II cellulose is described. Progressive transition between these forms with time was discovered for eucalyptus and microcrystalline cellulose at 97%RH. Locust bean gum (LBG) appeared to exert a protective effect on both eucalyptus and microcrystalline cellulose against the destruction of crystallinity by ball milling. For eucalyptus cellulose high levels of type I were produced during recrystallization with LBG under humid conditions. Both cellulose samples crystallized in the type I form in the presence of LBG whereas type II was produced in the presence of other hydrocolloids. Possible mechanisms for these unusual observations are proposed.
authors: Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK. Electronic address: abaszadeh@hotmail.com.
authors: A
authors: A
authors: Abbaszadeh
authors: Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.
authors: W
authors: W
authors: MacNaughtan
authors: Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK. Electronic address: tim.foster@nottingham.ac.uk.
authors: T J
authors: TJ
authors: Foster
keywords: Ball milling; Cellulose crystallinity; Hydrocolloid powder mixtures; Locust bean gum; X-ray powder diffraction