Abstract
The use of conductive polymer composites (CPCs) as strain sensors has been widely investigated. A wide range of strain sensitivities and high repeatability are vital for different applications of CPCs. In this study, the relations of the conductive filler network and the strain-sensing behavior and electrical stability under fatigue cycles were studied systematically for the first time based on the conductive polymethylvinylsiloxane (PMVS) composites filled with both carbon nanotubes arrays (CNTAs) and carbon black (CB). It was proved that the composites could be fabricated with large strain-sensing capability and a wide range of strain sensitivities by controlling the volume ratio of CNTA/CB and their amounts. Additionally, the CNTA/CB/PMVS composite with 3 vol % content of fillers showed high sensitivity (GF is 10 at 60% strain), high repeatability (the relative standard deviation (RSD) of the max R/R0 value is 3.58%), and electrical stability under fatigue cycles (value range of R/R0 is 1.62 to 1.82) at the same time due to the synergistic effects of the dual conductive network of CNTAs and CB. This could not be achieved by relying on a single CNTA or CB conductive network. This study may provide guidance for the preparation of high performance CPCs for applications in strain sensors.
Highlights
Conductive polymer composites (CPCs) have attracted a large amount of attention and been widely used in industry for applications such as electromagnetic interference (EMI) shielding, touch control switches and sensors [1,2,3] by virtue of easy fabrication methods, and the good electrical conductivity of conductive fillers
The strain-sensing behavior and electrical stability are closely related to the conductive filler network, which strongly depends on the filler contents and the volume ratio of carbon nanotubes arrays (CNTAs)/carbon black (CB)
With the increase of filler contents and the volume ratio of CNTA/CB, the conductive filler network enhanced, and the sensitivity of composites decreased, while the repeatability and electrical stability under fatigue cycles of composites improved with the increase of filler contents
Summary
Conductive polymer composites (CPCs) have attracted a large amount of attention and been widely used in industry for applications such as electromagnetic interference (EMI) shielding, touch control switches and sensors [1,2,3] by virtue of easy fabrication methods, and the good electrical conductivity of conductive fillers. The control of sensitivity for strain sensors is a vital issue, and some methods such as the addition of secondary fillers [19], the selective localization of filler in the matrix [20], and the use of mixed and functionalized fillers [21] have been demonstrated to modify the strain sensitivity of CPCs. Witt et al [22] prepared a conductive silicone rubber (SR) composite filled with both CNTs and CB, and the SR composite showed improvement in mechanical properties, high conductivity at a comparatively low concentration, and high sensitivity for tensile and compressive stress. We controlled the conductive filler network by choosing different filler contents and the volume ratio of CNTA/CB to try to achieve tunable sensitivity of composites, and eventually acquire composites with high sensitivity, high repeatability, and electrical stability under fatigue cycles
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