Eng 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 Dielectric region DC region  DC decrease with low amount of CNT!!!!!

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: 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. From this model is showed that:

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

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

Eng MWNT  ’ is related with the current through the resistors  ’’ is related with the current through the capacitors 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 The presence of CNT does not affect the conductance of the sample below the percolation point

Eng SWNT Same behavior!!! CNTs affect the resistor contribution of the composite, and at low frequencies changes in the dynamic of the polymers due to CNT decrease their conductivity

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

Eng8450 Effect of the temperature

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

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

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

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

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

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

Eng 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!!!

Eng 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!!!!

Eng MWNT Effect of the strain on the composite dynamic 12% MWNT

Eng MWNT Effect of the strain on the composite dynamic 12% MWNT 10 Hz

Eng SWNT Effect of the strain on the composite dynamic 0.05% SWNT 1.0% SWNT

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

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

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

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

PE3732C + MWNT 6% MWNT

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

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

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