Processing dependency of percolation threshold of MWCNTs in a thermoplastic elastomeric block copolymer

We prepared carbon nanotube thermoplastic elastomeric block copolymer nanocomposites using a commercial styrene–ethylenebutylene–styrene (SEBS) block copolymer and multiwall carbon nanotubes (MWCNTs) at different filler concentrations. Hereto we applied two different processing strategies, namely di...

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Bibliographic Details
Published in:Polymer (Guilford) 2011-04, Vol.52 (8), p.1788-1796
Main Authors: Meier, J.G., Crespo, C., Pelegay, J.L., Castell, P., Sainz, R., Maser, W.K., Benito, A.M.
Format: Article
Language:English
Subjects:
Applied sciences
Block copolymers
Carbon nanotube composites
carbon nanotubes
Composites
Dielectric spectroscopy
Dielectrics
Elastomers
electrical properties
Exact sciences and technology
Fillers
Forms of application and semi-finished materials
gap junctions
mechanical properties
mixing
nanocomposites
Nanostructure
Networks
Percolation
Polymer industry, paints, wood
polymers
Technology of polymers
Thermoplastic elastomers
Thermoplastic resins
thermoplastics
Thresholds
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Summary:We prepared carbon nanotube thermoplastic elastomeric block copolymer nanocomposites using a commercial styrene–ethylenebutylene–styrene (SEBS) block copolymer and multiwall carbon nanotubes (MWCNTs) at different filler concentrations. Hereto we applied two different processing strategies, namely direct melt mixing and solution-precipitation. We observe that the mechanical and electrical properties such as storage module and electrical percolation threshold are clearly affected by the processing approach. We studied these effects in detail by means of dielectric spectroscopy, which provided important information about the dispersion state of the MWCNT filler network. It revealed a fractal filler behaviour of the samples independent of the processing method. However, in samples prepared by melt mixing an additional dielectric response related to nanoscopic gap junctions of 1.5nm was identified. This response was not present in solution-mixed samples, which are characterized by improved polymer wetting. We discuss how the interactions between CNTs and the two phases of the block copolymer matrix are affected by the processing conditions resulting in the important differences in the filler network structure, which directly influence the final electrical and mechanical properties of the composite. [Display omitted]
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2011.02.024