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ball mill for nanoparticles fristch ball mill for the perfec

ball mill for nanoparticles fristch ball mill for the perfec

Ball milling: a green technology for the preparation and ...

This linear homopolysaccharide is composed of glucose units linked together through β glycosidic bonds.6 The cellulose chains are interconnected through hydrogen bonding and Van der Waals interactions to form elementary fibrils, which further assemble into larger micro and nanofibrils about 210 nm thick . Within these aggregates the cellulose chains can be organized into disordered amorphous like regions or into highly ordered crystalline structures. Depending on the unit cell dimensions and the polarity of the chains, cellulose can exist in different polymorphs .7 Cellulose I is the most common polymorph in native cellulose, whereas cellulose II is the crystal after different types of treatment. The term microfibrillated cellulose describes aggregates of cellulose nanofibers containing both amorphous and crystalline regions, which can be extracted from raw materials by a combination of mechanical and chemical actions. Nanofibers can be...

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Effects of milling on the properties of cellulose

A change in morphology of microcrystalline cellulose was also described by Zheng et al., who observed a morphological transformation of microcrystalline cellulose from rod like to spherical after ball milling was applied.21These particles were employed in combination with starch to produce some pastes, whose rheological properties were remarkably influenced by the concentration of microcrystalline cellulose and the milling time applied to obtain it. Further research on the effects of milling...

Preparation of cellulose nanocrystals

Lu et al. employed the ball mill to obtain nanocrystals from bamboo pulp by a mechano chemical treatment in the presence of phosphoric acid.38 The pulp was firstly pre treated using a Fibre Dissociation Device. The obtained material was then ball milled for 1.53.5 hours at 400 rpm in the presence of phosphoric acid to give a transparent solution. In this mechano chemical approach, phosphoric acid worked as a swelling agent during cellulose dissolution and facilitated the disintegration of ce...

Functionalisation of CNCs

Tang et al., for example, described a solvent free method to extract and chemically modify CNCs in the presence of maleic anhydride.45 This process was applied on cellulose pulp from filter paper, which was mechano chemically treated in a planetary ball mill with maleic anhydride and sulphuric acid at 500 rpm for 0.52 hours. This was followed by treatment in an ultrasonic reactor to improve the efficiency of the chemical reaction. The treatment with the ball mill had an effect on the yield .71The cellulose nanocrystals used as starting materials were obtained from bacteria and ground to a powder. These were milled together with PHBV using a centrifugal ball mill at 650 rpm for 60 minutes. The resulting composites were then moulded in a hot press to form thick films. The dispersion of the CNCs within the polymer matrix was studied by SEM, which showed a good dispersion and distribution of the crystals within the nanocomposites. Compared to PHBV, the nanocomposites exhibited better thermal stability, crystallinity, oxygen permeability and a reduction of water vapour diffusion. In a subsequent study, they also combined CNCs from bacterial sources with polylactic acid .72Also in this case, the nanocrystals were firstly ground and then mixed with the polymer using a centrifugal ball mill under the...

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Although ball milling technology has been exploited in process engineering, organic synthesis and the formation of nanocomposites, its potential to isolate and chemically modify cellulose nanoparticles has not been fully explored, as only a number of studies has been carried out. In particular, further studies on the functionalisation of CNCs and CNFs would be of great interest, as it is often problematic to react these materials, due to their low solubility in water and organic solvents. To our knowledge, esterification is the most commonly reported reaction; however, other types of chemical modification could be explored, although by the functional groups present. Options, for example, could be other reactions where the cellulosic hydroxyl groups act as a nucleophile. Moreover, since ball milling can be employed in dry and aqueous conditions, it could represent a green, sustainable technology for industrial application. Further studies on the preparation of cellulo...

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