# Preparation Methods and Properties of CNT/CF/G Carbon-Based Nano-Conductive Silicone Rubber
## 3 Results and Discussion
### Properties of the PREPARED Single-Filler Conductive Silicone Rubbers
Figure 9: Electrical properties of CNTs with different concentrations. (**a**) Volume resistivity. (**b**) Surface resistance. Figure 10 shows that the tensile strength, elongation at break, and elastic modulus of LSR/CNT decreased when the CNT concentration was increased from 0.5 to 1 wt%, because the mass fraction of the silicone rubber decreased while the content of CNTs increased. When the filling amount of CNTs was small, the CNT particles had little influence on the conductive silicone rubber composite system. When the concentration of CNTs was increased from 1 to 1.25 wt%, its tensile strength, elongation at break, and elastic modulus decreased relatively slowly; the tensile strength decreased from 1.69 Mpa to 1.60 Mpa, the elongation at break decreased from 850% to 759%, and the elastic modulus decreased from 0.40 Mpa to 0.35 Mpa, forming an infiltrated filler network at a lower CNT content [26]. In addition, LSR/CNT exhibited good mechanical properties. When the CNT concentration exceeded 1.25 wt%, the tensile strength, elongation at break, and elastic modulus rapidly decreased and were relatively unstable. The maximum tensile strength of 0.5 wt% carbon nanotube silicone rubber (SiR) prepared in reference [27] is only 0.51 MPa, which is lower than the tensile strength of 1.25 wt% carbon nanotube conductive silicone rubber (1.60 MPa) prepared in this paper, which indicates that the mechanical properties of carbon nanotube conductive silicone rubber prepared in this paper are good. According to the results of electrical and mechanical properties, the ideal CNT concentration is 1-1.25 wt%, and the composite properties of LSR/CNT with 1-1.25 wt% CNTs were explored. Dispersion analysis  
Figure 11 depicts the Raman spectra of LSR/CNT. Two distinct characteristic peaks were observed in the spectra at 1189 and 1237 cm\({}^{-1}\). The former is called the G mode and the latter is called the D mode. They stem from the impurities in CNTs and their own  
Figure 10: Mechanical properties of CNTs with different concentrations. (**a**) Tensile strength; (**b**) elongation at break; (**c**) elastic modulus. tubular defects. The strength ratio of the D and G modes is used to express the density of the tubular structure defects in multiwall CNTs. That is, R = Id/Ig (where I denotes the integral of the characteristic peak area), which signifies that the greater the ratio, the greater the defects of CNTs, the more uniform the dispersion, and the lower the degree of order. As shown in Figure 12, for CNT content of 1.25 wt%, T\({}_{\rm d.5\%}\) was 464.3 \({}^{\circ}\)C, T\({}_{\rm d.10\%}\) was 531.716 \({}^{\circ}\)C, and the corresponding temperature and weight loss at Tmax were 799 \({}^{\circ}\)C and 56.325%, respectively. Among the three studied carbon-based nano-conductive silicone rubber samples, LSR/CNT exhibited the best electrical properties, but its heat resistance reinforcement effect on silicone rubber was less than that of LSR/G and LSR/CF. A stable conductive network can be constructed when carbon nanotubes are filled with 1.25 wt%, and tensile sensitivity can be achieved even after bearing 500% tensile strain. Based on the data of the single-filler conductive silicone rubbers, the optimal proportion of the nano-fillers was obtained: 5.5 wt% for graphene, 1.25 wt% for CNTs, and 7.5 wt% for CFs.