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Eng8450 + MWNT

Eng8450 + MWNT. Sample annealed 15 minutes in the press (140 C) Around 30 minutes between put the sample in the equipment and to start the experiment.  DC decrease with low amount of CNT!!!!!. DC region. Dielectric region. How we can understand this “rare” behavior?.

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Eng8450 + MWNT

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  1. Eng8450 + MWNT Sample annealed 15 minutes in the press (140 C) Around 30 minutes between put the sample in the equipment and to start the experiment DC decrease with low amount of CNT!!!!! DC region Dielectric region

  2. How we can understand this “rare” behavior? Symmetric Hopping Model Based on the study of the displacement of a charge carrier from one position to another close by The nearest-neighbor jump rate (frequency) is: It is possible to show that the transition from DC to AC is determined by the smallest jump rate (c) , and the transition will be given by: From this model is showed that: So, it is possible to think that the presence of nanotubes increase the activation energy for the jump-rate of charge carriers or decrease its diffusion processes. At higher amount the last is compensated by the percolation process.

  3. Another approach based on the same arguments define the probability for a electron (“hole”) transition from state “a” to “b”, as: ’s are the reorganization energy It is showed that the response of the system to an alternating field is: The major contribution to the conductivity comes from polymer pair elements satisfying the last assumption!!! The response at very low frequencies involve pair states with very low transition rates. As a consequence the rare transitions from pair states into new states become more significant. Again, the presence of nanotubes could change the dynamic of charge carriers, decreasing the conductivity

  4. Another theory is based on the equivalent circuit concept: Any solid with spatially varying free charge conductivity and uniform charge dielectric constant At high frequencies the conductive regions are important and at low frequencies the isolated areas limit the charge carrier motion. Under AC conditions, it is defined: Conductance contribution Resistor contribution

  5. Eng8450 + MWNT ’ is related with the current through the resistors Below the percolation point, the high frequency area is influenced by the CNT (conductive) At low frequency, the isolated-region (bulk polymer) make the greater contributions ’’ is related with the current through the capacitors The presence of CNT does not affect the conductance of the sample below the percolation point

  6. Eng8450 + SWNT Same behavior!!! CNTs affect the resistor contribution of the composite, and at low frequencies changes in the dynamicof the polymers due to CNT decrease their conductivity

  7. The effect of the dynamic of the polymer on the conductivity is confirmed by the relaxation process observed in some composites Eng + 1.0 SWNT 3 hrs annealing 140 C Eng + 0.05 SWNT 3 hrs annealing 140 C

  8. Eng8450 Effect of the temperature

  9. Annealing Studies for some Eng/MWNT samples Effect of the amount of filler 12% MWNT Pure Eng 1Hz 1% MWNT

  10. Annealing Studies for some Eng samples Effect of the kind of filler 1% MWNT 1% SWNT

  11. Annealing Studies for some Eng samples Effect of the kind of matrix Eng 1% MWNT PE3732C 1% MWNT

  12. Annealing Studies for some Eng samples Effect of the kind of matrix Eng 12% MWNT PE3732C 12% MWNT 1Hz

  13. Annealing Studies for some Eng samples Effect of the kind of matrix Eng 1% SWNT PE3732C 1% SWNT

  14. Eng8450 + MWNT Effect of the strain on the composite dynamic 0.5 % MWNT The system is not able to relax during the shear-strain of 300% Small relaxation during shear-strain of 100% 1% MWNT 1 Hz 1 Hz

  15. Eng8450 + MWNT Effect of the strain on the composite dynamic 3% MWNT The shear-strain disrupt the conductivity but only in the beginning, after that the system relax independent of the strain!!!! At this condition the kinetic of the relaxation is modified by the external forces The location of this peak is shear-strain dependent!!!

  16. Eng8450 + MWNT Effect of the strain on the composite dynamic 6% MWNT It is clear that the drop in conductivity depends of the shear-strain, and again the system is able to relax independent of the shear-strain!!!!

  17. Eng8450 + MWNT Effect of the strain on the composite dynamic 12% MWNT

  18. Eng8450 + MWNT Effect of the strain on the composite dynamic 12% MWNT 10 Hz

  19. Eng8450 + SWNT Effect of the strain on the composite dynamic 0.05% SWNT 1.0% SWNT

  20. PE3732C + MWNT Sample annealed 15 minutes in the press (140 C) Around 30 minutes between put the sample in the equipment and to start the experiment Same behavior than Eng sample, the changes are related with the resistor contribution

  21. PE3732C + SWNT Sample annealed 15 minutes in the press (140 C) Around 30 minutes between put the sample in the equipment and to start the experiment

  22. PE3732C + MWNT Effect of the processing on the composite dynamic 6% MWNT This plot shows that the decrease in the conductivity is associated with the morphology of CNTs in the polymeric matrix

  23. PE3732C + MWNT Effect of the strain on the composite dynamic 0.05% SWNT 1% MWNT 1% SWNT 6% MWNT

  24. PE3732C + MWNT 6% MWNT

  25. PE3732C + MWNT Effect of the strain on the composite dynamic 12% MWNT

  26. PE3732C + MWNT Effect of the strain on the composite dynamic 12% MWNT 10% strain 100% strain Strain-induced insulation!!! 100% strain, 1 min Effect of time 100% strain, 20 min

  27. PE3732C + SWNT Effect of the strain on the composite dynamic 0.05% SWNT

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