Abstract
Dielectric thermoplastic elastomers (TPEs) offer a number of advantages over traditional dielectric elastomers or rubbers in terms of tailorable mechanical and electrical properties, higher mechanical strain, and ease of processing and shaping. Such a combination of properties has attracted increasing attention in flexible energy harvesting and storage applications. The combination of styrene–butadiene-styrene (SBS) and poly(vinylidene fluoride) (PVDF) has the potential to provide a combination of high elongation to break and increased relative permittivity, however the immiscibility between SBS and PVDF results in polymer blends with poor stretchability and processing properties. In this work, a dual percolated structure was created in a thermoplastic elastomer of SBS/PVDF (50/50 wt%), by coupling EVA as a compatibiliser for SBS/PVDF with multi-walled carbon nanotubes (MWCNTs) as a conductive filler that created an electrical percolation network. The elongation at break of SBS/PVDF was significantly enhanced by adding 20 wt% of EVA due to the reduced phase dimensions and enhanced interfacial adhesion. The addition of MWCNTs enabled the formation of a percolated network at 1 wt% in the SBS phase, followed by a second percolation at 3 wt% in both PVDF and SBS phases. The relative permittivity of the composite increased to 22.5 at 1 wt% MWCNT with a tan δ of 0.5, and further increased to 34.9 for a 2 wt% of MWCNT concentration while the tan δ remained constant. In-situ electrical testing for the SBS/PVDF thermoplastic elastomer under strain showed that, at 1 wt% MWCNT, the non-percolated PVDF islands acted as variable capacitors whose capacitance increased with degree of stretching. For the dual percolated structure formed at 3 wt% MWCNT, the capacitance and conductivity of the composites were unaffected up to 30% strain. The high relative permittivity and strains of over 100% means that the SBS/PVDF based thermoplastic elastomer is readily suitable for vibration control sensors, variable impedance devices, energy harvesters and artificial muscles and actuators.
Original language | English |
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Pages (from-to) | 504-514 |
Number of pages | 11 |
Journal | European Polymer Journal |
Volume | 112 |
Early online date | 16 Jan 2019 |
DOIs | |
Publication status | Published - 1 Mar 2019 |
Funding
CE thanks EPSRC and Jaguar Land Rover (UK) for funding a PhD studentship (iCASE award). XY thanks China Scholarship Council for funding. Appendix A
Keywords
- Compatibility
- Composite
- Dielectric properties
- Double percolation threshold
- Thermoplastic elastomer
ASJC Scopus subject areas
- General Physics and Astronomy
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry
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Chris Bowen
- Department of Mechanical Engineering - Professor
- Faculty of Engineering and Design - Associate Dean (Research)
- Centre for Sustainable Chemical Technologies (CSCT)
- Centre for Nanoscience and Nanotechnology
- Institute for Mathematical Innovation (IMI)
- Institute of Sustainability and Climate Change
- Centre for Integrated Materials, Processes & Structures (IMPS)
- IAAPS: Propulsion and Mobility
Person: Research & Teaching, Core staff, Affiliate staff