![](bg5.png)
Figure 6: Fitting of experimental curve of change of
resistance in time at constant 6.6 % strain deformation
with equation (2) taking into account three mean
relaxation times:
1
= 1754,
2
= 197, and
3
= 22s.
aggregates have enough time to relax, therefore R
also relaxes with time when the mechanical loading
and the strain sensitivity is the highest. At higher
(>1Hz) frequencies CB aggregates have a difficulty
to follow the macromolecular chains during loading,
so the strain sensitivity decreases versus frequency.
4 CONCLUSIONS
It was shown that the polyisoprene high structure
carbon black composite samples can be used for
periodically changed mechanical load or mechanical
vibration testing. The maximal and minimal values
of resistivity increase with mechanical load
frequency while the piezoresistivity effect decreases.
These can be explained by analysing the
experimentally determined values of relaxation
times of carbon black aggregates and polymer
chains. The limiting factors for use of the developed
sensors at higher mechanical load frequencies are
the rise of maximal and minimal resistivity as well
as the decrease of piezoresistivity versus frequency.
ACKNOWLEDGEMENTS
This study was supported by ESF Grants Nr.
1DP/1.1.1.2.0/13/APIA/VIAA/021.
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