Synergistic effects in network formation and electrical properties of hybrid epoxy nanocomposites containing multi-wall carbon nanotubes and carbon black

Synergistic effect in conductive networks constructed with carbon nanofillers in different dimensions

“…As widely reported in the literature [4,32], the percolation threshold of CPCs can be determined accurately, and information on the dimensionality of the conducting network can be obtained through the fitting of classical percolation scaling law to experimentally obtained conductivity data. Hence, the percolation threshold P c and exponent t are obtained, the results are shown in Figure 2 Zhang et al -eXPRESS Polymer Letters Vol.6, No.2 (2012) Recently, it is reported that the percolation threshold of ternary systems containing two types of conductive fillers can be estimated by using an equation derived from the excluded volume approach [26,29,33] (Equation (3)):…”

“…Furthermore, excluded volume theory has been widely used in conductive polymer composites filled with one type of conductive filler to analyze their conductive percolation behavior [19,24]. Recently, it is reported that the percolation threshold of ternary systems containing two types of conductive fillers can be estimated by using an equation derived from the excluded volume approach [26,29,33] (Equation (3)):…”

“…Regarding the formation of conductive network with fillers in different aspect ratios, theoretical study has shown that it is not necessary to build conductive network with high aspect ratio filler alone [26], and the percolation threshold is sensitive to the portion of high aspect ratio filler in a system containing fillers in different aspect ratios [27]. There are a number of investigations reported in the literature on mixed carbon fillers filled CPCs [26,[28][29][30][31]. However, the percolation thresholds of these systems filled with mixed fillers are only simple average of that for systems filled with a particular kind of carbon filler.…”

“…It is thought that there are three different mechanisms of conductive network formation in such a ternary system (see Figure 6d, 6e, 6f). Mechanism 1: shortcut of 'dead' network branches caused by new active branches of networks co-formed by CB [29]; mechanism 2: incorporation of CB into active 'MWNT' networks through bridging MWNT local networks with CB [29]; and mechanism 3: bridging local contacts between CB clusters through MWNTs. In the different ternary systems investigated in current study, mechanism 3 might be dominant in CPC-MWNT 1 -CB4, as most of the conductive networks are formed by CB.…”

Modelling percolation in fibre and sphere mixtures: Routes to more efficient network formation

“…The results are relevant to understanding rheological [24] and phase behaviour [25][26][27][28][29], as well as computer simulation studies [30][31][32][33] of rod-sphere mixtures. The experimental relevance of such work is demonstrated in a recent paper by Sumfleth et al [34], who found that for an conductive epoxy nanocomposite, a considerable amount of multi-wall carbon nanotubes (MWCNTs) can be replaced by carbon black (CB) without changing the electrical properties. Since MWCNTs are currently more expensive than CB per unit mass, this may have important cost implications for the manufacture of electrically conductive composites.…”