Extensive research conducted by Polymer Aging Concepts in cooperation with Georgia Tech and Rockbestos Surprenant Cable Corporation has focused on industrial applications for PE, silicone rubber and EPR.
Research Abstracts and Conclusions
Georgia Tech School of Materials Science and Engineering — conclusions
from the abstract on AgeAlert research conducted for the U.S.
Department of Energy:
Polymeric materials are widely used as insulation and jacketing
materials in wire and cable. When such materials are used
for long-term applications, they undergo thermal oxidation aging
in the environment. It is necessary to develop an in-situ
and non-destructive condition monitoring (CM) method to follow
the aging of cable materials. The main objective of this
work is to investigate potential conductive polymer composites
materials which can be used as potential sensor materials
for this purpose. Different polymers were used as the matrix
and the proper formulations were also investigated with
filler loading below the percolation threshold. The CPC materials
underwent aging experiments at accelerated thermal oxidation.
The aged samples were characterized as the material properties
change in terms of weight, density, and mechanical properties,
as well as the electrical properties.
The results indicated that the substantial resistivity decreases
of the CPC composites could be directly related with the increases
in volume fraction of the conductive filler, which was mainly
caused by the mass loss of polymer matrix and sample shrinkage
during the thermal oxidation aging process. Compared to existing
CM method based on density change, the electrical resistivity
is more explicit regarding its absolute changes throughout the
thermal oxidation aging.
The results offer strong evidence that resistivity measurements,
which reflect property changes under thermal aging conditions,
could represent a very useful and non-destructive CM approach
as well as a more sensitive method than density CM approach.
At the same time, the effects of antioxidant, filler and
matrix to the electrical properties of composite materials
were also studied and potential formulations of the sensor
materials were found. The life time of the material was also
predicted by the Arrhenius method. In another part of the research,
the aging experiments of the CPC composite materials under
the radiation aging condition were also performed and the results
were presented.
Polymer Aging Concepts, Inc. -- conclusions from the final report
on AgeAlert research conducted for the U.S. Department of Energy:
- Resistivity of conductive composites
correlates with mechanical properties as they age in thermal-oxidative
environments.
- Resistivity of conductive composite age sensors can be
used to predict remaining life of sensor materials.
- Resistivity data can be communicated by contact readings
or wired and wireless means.
- Age sensors can be integrated into passive radio frequency
identification devices (RFIDs).
Conclusions from article written for the Journal of Applied
Polymer and Science entitled "Electrical Approach to Monitor
the Thermal Oxidation Aging of Carbon Black Filled Ethylene Propylene
Rubber" by Yangyang Sun, Lianhua Fan, Ken Watkins, Jonathan
Peak and C. P. Wong:
Carbon black filled EPR composite showed
large changes in resistivity at the time that the mechanical
failure of material was reached. These results indicate that
electrical measurement in terms of resistivity for conductive
composite could be used as a potential non-destructive in-situ
measurement for cable condition monitoring. Further analysis
of experiment data shows that the decrease of resistivity is
mainly due to the CB volume fraction increasing caused by thermal
degradation of polymer components. The experiments also show
that the composite with high CB loading had a slower degradation
due to the antioxidant effect of carbon black.
Bibliography
The following bibliography may be useful if you're investigating
degradable material monitoring.
- Robert J. Lofaro, “A review of Electric Cable Aging
Effects and Monitoring Programs for Plant License Renewal”,
Brookhaven National Laboratory BNL-NUREG-66523
- Kenneth T. Gillen and Roger L. Clough, “Prediction of
Elastomer Lifetimes from Accelerated Thermal-Aging Experiments”,
SAND097-1900C, 1997.
- K. T. Gillen, M. Celina and R. L. Clough, “Density Measurements
as a Condition Monitoring approach for Following the Aging of
Nuclear Power Plant Cable Materials”, presented at
the Cable Condition Monitoring Working Group, 2000.
- V. E. Gul’, “Structure and Properties of Conducting
Polymer Composites,” VSP, The Netherlands, 1996.
- Shijian Luo, C. P. Wong, “Conductive Polymer Composites
with Positive Temperature Coefficient”, School of Materials
Science and Engineering, Georgia Institute of Technology,
1997.
- Y. Sun.; S. Luo,.; C.P. Wong,, Polym. Deg. Stab.
2004, 86, 209-215
- K. S. Watkins et al., WIPO publication WO 03/076953
A2 published 18 September 2003.
- K. Watkins, S. J. Morris, D. Masakowski, C.P. Wong,
S. Luo, (2003) “An Electrical Condition Monitoring Method for Polymers”,
WIPO Publication No. WO 03/076953A2, 18 September, 2003.
- K. Watkins, Jr, S. J. Morris, Jr, “An Electrical
Condition Monitoring Method for Polymers, DOE SBIR Final
Report 4/2002
- K. Watkins, Jr., and S. J. Morris, Jr.,
U. S. Patent 5,862,030 “Electrical
Safety Device with Conductive Polymer Sensor, Jan 19, 1999
- Yangyang Sun, Lianhua Fan, Ken Watkins,
Jonathan Peak and C. P. Wong, "An Electrical Approach to Monitor Wire and
Cable Thermal Oxidation Aging Condition Based on Carbon Black
Filled Conductive Polymer Composite", Journal of Applied
Polymer and Science, Vol. 93, No. 2, Pp. 513-520 (2004)
- Yangyang Sun, Lianhua Fan, Ken Watkins,
Jonathan Peak and C. P. Wong, "An Electrical Approach to Monitor Wire and
Cable Thermal Oxidation Aging Condition Based on Carbon Black
Filled Conductive Polymer Composite",
Journal of Applied Polymer and Science,
Vol. 93, No.2, Pp. 513-520 (2004)
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