Electrical characterization of deformation behavior of carbon-based conductive filled nanocomposites under constant amplitude fatigue loading

Abstract

Elastomer-based nanocomposites(EcNs) were prepared with a novel mixing method to determine the deformation properties under constant amplitude dynamic operating conditions. The fillers of EcNs consists of functionalized(M-FCNTs) and nonfunctionalized carbon-nanotubes(M-NCNTs), graphite(GF) and carbon black(CB). In this study, six different mixtures were prepared using M-FCNT, and M-NCNT fillers in 1, 2, 3 phr ratios, except for a CB-filled reference mixture(C00). Graphite, which has exfoliation and excellent lubricating properties1, was added to six mixtures at the rate of 1 phr to prevent agglomeration of M-CNTs in the mixtures. SEM images show that M-CNTs are homogeneously distributed, interacting strongly with GF, and M-FCNTs have a better interface interaction than M-NCNTs. During crosslinking of M-NCNT filled EcNs, due to the resistance in the direction of the polymer chain's movement, the difference between minimum torque and maximum torque increased by approximately 10% compared to M-FCNTs. The lost energy (ΔW) between the loading and unloading curves of M-NCNT filled EcNs increased compared to the M-FCNT filled mixtures and C00. The resistance properties depending on the samples' strain value showed a more stable and repetitive behavior in M-FCNT filled EcNs with a ratio of 1 and 2 phr, called F-C01 and F-C02, respectively. The semiconductor F-C01 sample showed the most stable behavior due to preserving the conductive filler network's structural order during the fatigue test, although the average resistance change was highest with 1.51E + 07 Ω. We discuss ways to use conductive elastomer composites as an effective deformation detection sensor in dynamic applications based on the results.

Resistance sensing response optimization and interval loading continuity of multiwalled carbon nanotube/natural rubber composites: Experiment and simulation

“…Compared with the amplitude without prestrain (Figure 5a,c: jagged R/R 0 amplitude and strong 'shoulder peak'), the amplitude of R/R 0 for the prestrain composite changes linearly with increasing cycles because a strong conductive network of the composite is formed by the prestrain, improving the linearity of the resistance peak. Moreover, there is a hysteresis effect of conductive network recovery in the process of cycling, 15 which leads to a decrease in the resistance amplitude after the prestrain. The monotonous R/R 0 variation of MWCNT/NR composites was enhanced by the prestrain under cyclic strains of 50% and 100%, and the 'shoulder peak' gradually weakened or even disappeared with excellent repeatability (see Figure 5b,d), which is attributed to the destruction of the poorly conductive network by the prestrain, the untangling of MWCNTs 27,28 and the change of orientation of the conductive network (see Sections 3.5 and 3.7 for details) and the formation of additional CPs through the breakdown and subsequent formation of an interface between the filler and matrix during the prestrain process, improving the linearity and monotone of the sensing response.…”

“…where β 1 , β 2 , β 3 and β 4 are constants. Substituting Equation (15) and Equation ( 14) into Equation ( 12) yields:…”

“…At the same time, the stability and repeatability of the sensing response of the composite are improved. Unfortunately, the conductivity of the composite is reduced due to the formation of higher resistance values 14,15 . Unfunctionalized MWCNTs have significant resistance response fluctuations, but they are economical and simple conductive fillers 15 .…”

“…Unfortunately, the conductivity of the composite is reduced due to the formation of higher resistance values. 14,15 Unfunctionalized MWCNTs have significant resistance response fluctuations, but they are economical and simple conductive fillers. 15 Therefore, it is necessary to optimize the resistance response of the composite and establish the corresponding relationship between sensors to achieve the long-term effective monitoring ability of isolation bearings.…”