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Anisotropic reversible piezoresistivity in magnetic-metallic/polymer structured elastomeric composites: modelling and
José Luis Mietta1, Pablo I Tamborenea, R Martin Negri
1Instituto de Química Física de Materiales, Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina. rmn@qi.fcen.uba.ar.
Soft Matter
|October 20, 2015
Summary
Structured elastomeric composites with aligned pseudo-chains exhibit anisotropic piezoresistivity. A new model accurately predicts their electrical resistance under stress, crucial for advanced sensors.
Area of Science:
- Materials Science
- Nanotechnology
- Polymer Science
Background:
- Electrically conductive fillers in elastomeric composites can lead to anisotropic piezoresistivity.
- Existing filler structures like string-of-particles do not fully capture complex conduction mechanisms.
Purpose of the Study:
- To propose and validate a constitutive model for anisotropic reversible piezoresistivity in structured elastomeric composites (SECs).
- To analyze electrical conduction mechanisms within pseudo-chains formed by magnetically aligned micro-clusters.
Main Methods:
- Formation of pseudo-chains using micro-sized clusters of nanomagnetic particles coated with noble metals (e.g., silver) within a polymer matrix (PDMS).
- Magnetic field alignment during composite curing to create anisotropic filler structures.
- Development of a constitutive model incorporating electron tunneling, intra-chain conduction, and inter-chain resistivity.
- Experimental validation using Fe3O4[Ag] microparticles under applied normal stress.
Main Results:
- The proposed model accurately fits experimental electrical resistance data for magnetically aligned Fe3O4[Ag] microparticles in PDMS.
- The model accounts for electron tunneling, conduction within pseudo-chains, and chain-contact resistivity.
- Evaluation of parameter sensitivity (potential barrier, tunneling distance) and prediction of tunneling gaps within pseudo-chains.
Conclusions:
- The developed model provides a robust framework for understanding and predicting anisotropic piezoresistivity in SECs.
- The findings are significant for designing advanced piezoresistive sensors with tunable properties.
- Simulations highlight the influence of material properties like Young's modulus on piezoresistive behavior.
