Long-time low-impact ball milling of multi-wall carbon nanotubes

Kukovecz, Ákos; Kanyó, Tímea; Kiricsi, Imre

doi:10.1016/j.carbon.2004.11.030

Cited by 139 publications

(62 citation statements)

References 26 publications

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“…For this to be the case, the distributions need to have a large positive skewness γ (larger than, say, 2), or, equivalently, a large scaled variance s. Clearly, this coupling between the skewness and the spread is not present for a distribution with more than two independent moments, but in the discussion below we show that a large value of s does actually imply a large skewness and that a large variance without any skewness is not sufficient to obtain a low PT. In any event, for those few CNT systems for which the moments of the length distributions have actually been determined, the skewness and spread seem to be quite small, i.e., γ = 0.40 and s = 0.20, giving φ p (x)/φ p (x 0 ) = 0.84, 40 or φ p (x)/φ p (x 0 ) = 0.64, 48 or φ p (x)/φ p (x 0 ) = 0.50 for an exponential distribution; 43,44 so for these the effect of polydispersity is modest. Given the very large scatter in measured PTs of carbon-nanotube composites, 17 we conclude that the skewness in the distributions must usually, in fact, be much larger than this.…”

Section: Realistic Size Distributionsmentioning

confidence: 99%

Connectivity percolation of polydisperse anisotropic nanofillers

Otten¹,

Schoot²

2011

The Journal of Chemical Physics

127

168

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We present a generalized connectedness percolation theory reduced to a compact form for a large class of anisotropic particle mixtures with variable degrees of connectivity. Even though allowing for an infinite number of components, we derive a compact yet exact expression for the mean cluster size of connected particles. We apply our theory to rodlike particles taken as a model for carbon nanotubes and find that the percolation threshold is sensitive to polydispersity in length, diameter, and the level of connectivity, which may explain large variations in the experimental values for the electrical percolation threshold in carbon-nanotube composites. The calculated connectedness percolation threshold depends only on a few moments of the full distribution function. If the distribution function factorizes, then the percolation threshold is raised by the presence of thicker rods, whereas it is lowered by any length polydispersity relative to the one with the same average length and diameter. We show that for a given average length, a length distribution that is strongly skewed to shorter lengths produces the lowest threshold relative to the equivalent monodisperse one. However, if the lengths and diameters of the particles are linearly correlated, polydispersity raises the percolation threshold and more so for a more skewed distribution toward smaller lengths. The effect of connectivity polydispersity is studied by considering nonadditive mixtures of conductive and insulating particles, and we present tentative predictions for the percolation threshold of graphene sheets modeled as perfectly rigid, disklike particles.

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Section: Realistic Size Distributionsmentioning

confidence: 99%

Connectivity percolation of polydisperse anisotropic nanofillers

Otten¹,

Schoot²

2011

The Journal of Chemical Physics

127

168

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“…Ball milling has been frequently used to cut short carbon nanotubes (CNT) by breaking C-C bonds. 15,16 For graphite, the stacked parallel graphene layers tend to slip apart upon milling because of weak van der Waals forces between them. A wet ball milling method was recently employed to exfoliate graphite to form graphene.…”

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confidence: 99%

Size effect of graphene on electrocatalytic activation of oxygen

et al. 2011

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“…18 Various forms of ball-milling, also referred to as mechanical alloying (MA) or mechanical mixing, have been utilized to disperse nanometer-and micrometer-sized reinforcement agents, including CNTs, in MMCs, as the process allows for thorough mixing at relatively low temperatures. At the same time, it is well known that milling under improper conditions can also damage the CNT [19][20][21] or lead to carbide formations. 22 Even if temperatures remain low during milling, the induced residual strain and defects in the material enhance the likelihood for chemical reactions to occur during the following powder consolidation steps.…”

Section: Introductionmentioning

confidence: 99%

Low temperature synthesis of carbon nanotube-reinforced aluminum metal composite powders using cryogenic milling

et al. 2014

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temperature synthesis of carbon nanotube-reinforced aluminum metal composite powders using cryogenic milling. "J. Mat. Sci. 29, 2644(2014 Carbon nanotube (CNT)-reinforced aluminum composite powders were synthesized by cryogenic milling. The effects of different cryogenic milling parameters and CNT contents on the structural characteristics and mechanical properties of the resulting composite powders were studied. Detailed information on powder morphology and the dispersion and structural integrity of the CNTs is crucial for many powder consolidation methods, particularly cold spray (CS), which is increasingly utilized to produce metal-based nanocomposites. While all of the produced composite powders exhibited particle sizes suitable for spray application, it was found that with increasing CNT content, the average particle size decreased and the size distribution became narrower. The dispersion of CNTs improved with milling time and helped to maintain a small Al grain size during cryogenic milling. Although extensive milling allowed for substantial grain size reduction, the process caused notable CNT degradation, leading to a deterioration of the mechanical properties of the composite.

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Long-time low-impact ball milling of multi-wall carbon nanotubes

Cited by 139 publications

References 26 publications

Connectivity percolation of polydisperse anisotropic nanofillers

Connectivity percolation of polydisperse anisotropic nanofillers

Size effect of graphene on electrocatalytic activation of oxygen

Low temperature synthesis of carbon nanotube-reinforced aluminum metal composite powders using cryogenic milling

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