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Dielectro -Rheological Device (DRD)

Dielectro -Rheological Device (DRD). Dielectric Spectroscopy: The measurement. Electrical current flowing through a sample as a response to an alternating electric field is measured as a function of the field frequency

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Dielectro -Rheological Device (DRD)

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  1. Dielectro-Rheological Device (DRD)

  2. Dielectric Spectroscopy: The measurement • Electrical current flowing through a sample as a response to an alternating electric field is measured as a function of the field frequency • Dielectric spectrum gives information on structure and behavior of the material Voltage Voltage application DC or AC voltage + Dielectric + Induction of an - electric field - LCR meter Current Measurement of the flowing current

  3. Dielectro-Rheological Device (DRD) • Setup for Peltier and CTD chambers • available • Contact at upper geometry by spring • (Rotation) or wire (Oscillation) • Applications • Filled rubbers • Polymers nanocomposites • carbon nanotubes • clays • Battery research • Conductivity of filled polymers

  4. Ceramic isolation Goldspring or -wire contact Measuring Plate PP25/PP50 The bottom measuring plate is isolated to the Rheometer Sample Contact Peltier Counter Cooling Rheo-Dielectric-SpectroscopyDielectro Rheological Device DRD • An electrical potential is applied by a spring system onto the shaft and the capacitance is measured. • Uniform temperature distribution with Peltier Hood (-40°C - +200°C)

  5. Dielectro Rheology Example: Polymer Carbon Black Composite • Carbon black clusters dispersed in a polymer matrix. • Carbon black induces dielectric properties in the composite. Rheology: (Shear stress: 65400 Pa) Dielectricity: (Frequency: 1 kHz) • Slow mechanical relaxation of long chain polymers • Fast electrical relaxation of carbon black clusters

  6. Epoxy resin filled with carbon nanotubes The nanotubes are inducing electric conductivity in the resin. Flow curve: 0.1 – 100 s-1 , 1 kHz and 1V • Capacity changes due to an orientation of the nanotubes

  7. Epoxy resin filled with carbon nanotubes Strain sweep 0.1 -1000% at 10 1/s, 1kHz and 1V • Capacity is constant within the linear viscoelastic range and decreases in the non- • linear regime due to an alignment in flow direction.

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