Influence of shear deformation on carbon nanotube networks in polycarbonate melts: Interplay between build-up and destruction of agglomerates

Skipa, Tetyana; Lellinger, Dirk; Böhm, Wolfgang; Saphiannikova, Marina; Alig, Ingo

doi:10.1016/j.polymer.2009.11.047

Cited by 136 publications

(131 citation statements)

References 46 publications

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“…This indicates that the destruction of conductive paths dominates at the beginning of the shear. After several oscillations, the amplitude decreases, which means that the build-up of new pathways takes place already during the shear which corresponds to the explanations given in the literature [5,6,14,15]. In order to get more information about the pathway destruction at the beginning of the oscillatory shear, this effect was evaluated for different deformation amplitudes.…”

Section: Resultsmentioning

confidence: 77%

Shear induced electrical behaviour of conductive polymer composites

Starý¹,

Krückel²,

Schubert³

2013

AIP Conference Proceedings

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Abstract. The time-dependent electrical resistance of polymethylmethacrylate containing carbon black was measured under oscillatory shear in the molten state. The electrical signal was oscillating exactly at the doubled frequency of the oscillatory shear deformation. Moreover, the experimental results gave a hint to the development of conductive structures in polymer melts under shear deformation. It was shown that the flow induced destruction of conductive paths dominates over the flow induced build-up in the beginning of the shear deformations. However, for longer times both competitive effects reach a dynamic equilibrium and only the thermally induced build-up of pathways influences the changes in the composite resistance during the shear. Furthermore, the oscillating electrical response depends clearly on the deformation amplitude applied. A simple physical model describing the behaviour of conductive pathways under shear deformation was derived and utilized for the description of the experimental data.

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Section: Resultsmentioning

confidence: 77%

Shear induced electrical behaviour of conductive polymer composites

Starý¹,

Krückel²,

Schubert³

2013

AIP Conference Proceedings

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“…In the quiescent state of melt the destroyed agglomerates were found earlier to be rebuilt in the process of quiescent agglomeration [12][13][14][15]. As stated already in [36], for a more realistic description of the filler network and its dependence on the thermo-rheological history a 'superstructure' has to be taken into account, e.g. a distribution of agglomerate sizes or a spinodal-type superstructure.…”

mentioning

confidence: 91%

“…In our first simplified approach [12,13] we assumed, that the 'percolation' path is formed by sphere-like conductive agglomerates, containing loosely packed CNTs. These agglomerates can be formed or destroyed in shear flow [35,36]. For steady shear conditions constant values for the electrical conductivity and the dynamic shear modulus were found, indicating a stationary state of the filler network due to the competition of shear-induced build up and destruction [35,36].…”

mentioning

confidence: 95%

“…These agglomerates can be formed or destroyed in shear flow [35,36]. For steady shear conditions constant values for the electrical conductivity and the dynamic shear modulus were found, indicating a stationary state of the filler network due to the competition of shear-induced build up and destruction [35,36]. In the quiescent state of melt the destroyed agglomerates were found earlier to be rebuilt in the process of quiescent agglomeration [12][13][14][15].…”

mentioning

confidence: 97%

“…In particular, for description of the time-dependent electrical conductivity a hierarchical model [36] assuming different types of agglomerated has been used to fit the experimental data. In the previous studies [36][37][38] the coupling approach has been tested using either the classical percolation theory [39] or the Generalized Effective Medium (GEM) approximation [40]. Here we present a different superposition approach in which the filler particles are assumed to be separated into percolating and non-percolating phases.…”

mentioning

confidence: 99%

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Superposition approach for description of electrical conductivity in sheared MWNT/polycarbonate melts

Saphiannikova¹,

Skipa²,

Lellinger³

et al. 2012

Express Polym. Lett.

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The theoretical description of electrical properties of polymer melts, filled with attractively interacting conductive particles, represents a great challenge. Such filler particles tend to build a network-like structure which is very fragile and can be easily broken in a shear flow with shear rates of about 1 s–1. In this study, measured shear-induced changes in electrical conductivity of polymer composites are described using a superposition approach, in which the filler particles are separated into a highly conductive percolating and low conductive non-percolating phases. The latter is represented by separated well-dispersed filler particles. It is assumed that these phases determine the effective electrical properties of composites through a type of mixing rule involving the phase volume fractions. The conductivity of the percolating phase is described with the help of classical percolation theory, while the conductivity of non-percolating phase is given by the matrix conductivity enhanced by the presence of separate filler particles. The percolation theory is coupled with a kinetic equation for a scalar structural parameter which describes the current state of filler network under particular flow conditions. The superposition approach is applied to transient shear experiments carried out on polycarbonate composites filled with multi-wall carbon nanotubes

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Carbon Nanotube Polymer Composites

Nobile

2012

Wiley Encyclopedia of Composites

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Carbon nanotubes (CNTs) have excellent mechanical, electrical, and thermal properties, and they are considered to be potential ideal fillers in polymers to produce low weight nanocomposites of high performance. This article reviews the thermal, rheological, mechanical, and electrical properties of CNT polymer composites. The crystallization behavior of polymer nanocomposites in the presence of CNTs is discussed because it strongly influences the mechanical properties of the filled polymers. It is, then, shown that the investigation of the rheological properties of CNT composite melts is fundamental to the comprehension of the dynamics and microstructure of CNT polymer composites. New results of the linear viscoelastic behavior and steady‐shear flow of CNT polymer composites are reported and analyzed. After that, the critical issue of the transfer of the superior properties of the CNTs to the nanocomposites is reviewed and discussed. Effective reinforcement can occur only if an adequate interfacial adhesion between the phases is obtained and a stable homogeneous dispersion of the individual CNTs in the host polymer matrix is achieved. If this event occurs, CNT polymer composites show significant improvements in the mechanical properties and electrical conductivity of the polymer matrix; the literature results are summarized and discussed.

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Influence of shear deformation on carbon nanotube networks in polycarbonate melts: Interplay between build-up and destruction of agglomerates

Cited by 136 publications

References 46 publications

Shear induced electrical behaviour of conductive polymer composites

Shear induced electrical behaviour of conductive polymer composites

Superposition approach for description of electrical conductivity in sheared MWNT/polycarbonate melts

Carbon Nanotube Polymer Composites

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