## 3 Results and Discussion
### Mechanical Analysis  
The stress-strain curves of the VNR/MWCNT nanocomposite specimens with different MWCNT fillers are shown in Figure 5. In Figure 5, the stress-strain curves of the VNR/MWCNT nanocomposite specimens exhibit typical properties related to elastomeric materials; that is, high elasticity is reflected in high strain at the break (\(\varepsilon_{\textit{atbreak}}\)) and high stress at the break (\(\sigma_{\textit{atbreak}}\)). In Figure 5, it is evident that increasing the concentration of MWCNTs in the NVR matrix impacts the mechanical properties of the VNR/MWCNT nanocomposites. As the concentration of MWCNT in the VNR/MWCNT nanocomposite increases, the \(\varepsilon_{\textit{atbreak}}\) value decreases, indicating that the material has become more rigid [64]. Increasing MWCNT concentration, however, does not produce significant variations in the \(\sigma_{\textit{atbreak}}\) value. According to the stress-strain curves of all the VNR/MWCNT nanocomposite specimens, the MWCNTs efficiently acted as reinforcement, absorbing part of the mechanical stress imposed on the VNR matrix.  
In a study of NR-based nanocomposites reinforced with carbon black (CB) and MWCNTs, [PERSON] et al. observed the same behavior, mainly in regard to tensile strength (TS) for different concentrations of MWCNTs [31]. According to the authors, a reduction in TS may be due to poor dispersion of the filler, particularly in samples containing 5 phr of MWCNT. In a study conducted by [PERSON] et al., the dispersion, electrical conductivity, mechanical properties, and resistance-strain response behaviors of MWCNT/NR composites were investigated using different processing conditions [65]. In terms of tensile properties, the  
Figure 5: Stress–strain curves of VNR/MWCNT nanocomposites with different concentrations of MWCNT fillers.  
authors found that stress increases with strain and MWCNT content, while tensile strain decreases with MWCNT content  
As shown in Table 4, the mechanical parameters of the stress-strain curves extracted from Figure 5 are as follows: tensile strength at 100% (\(\sigma_{100\%}\)), 300% (\(\sigma_{300\%}\)), and 500% (\(\sigma_{500\%}\)) stress; \(\sigma_{\text{at break}}\); and \(\epsilon_{\text{at break}}\).  
The incorporation of MWCNTs into the VNR matrix resulted in a gradual increase in \(\sigma_{100\%}\), \(\sigma_{300\%}\), and \(\sigma_{500\%}\) values for all the specimens. However, when considering the statistical error, it appears that the presence of fillers does not significantly change the \(\sigma_{\text{at break}}\) values in comparison to all the nanocomposite specimens. Alternatively, the \(\epsilon_{\text{at break}}\) values were reduced. There is a positive effect of the reinforcing properties of the MWCNTs, as well as the restriction in the mobility of the VNR polymer chains as a result of the interaction between the filler and matrix, resulting in stiffening of the VNR/MWCNT nanocomposite specimens. There was a significant increase in the tensile strength of the VNR/MWCNT nanocomposite specimens because of good adhesion between the VNR and the MWCNTs. As a result of this behavior, the MWCNTs were utilized as reinforcement agents within the VNR matrix, resulting in an improvement in the mechanical properties of the nanocomposites.