# Mechanism and Characterization of
## 4 Conclusions  
The objective of this study was to improve the dispersion of fillers within a natural rubber latex (NR) matrix. NR composites, multi-walled carbon nanotube (MWCNT)/NR (MNR) composites, silica (SiO\({}_{2}\))/NR (SNR) composites, and MWCNT-SiO\({}_{2}\)/NR (MSNR) composites were prepared using a solution blending method to investigate the effects of dual-component MWCNT and SiO\({}_{2}\) fillers on NR composites. Mixing multi-walled carbon nanotubes with silica in a natural rubber latex matrix produces a significant synergistic effect and improves the mechanical and dispersive properties, making this composite material suitable for a wide range of applications in the fields of automobile tires, conveyor belts, and electrical insulation materials. The following conclusions were drawn:  
(1) After adding MWCNTs and SiO\({}_{2}\), the tensile strength, elongation at break, and Young's modulus of the NR composites increased by 59.85%, 71.44%, and 28.74%, respectively. (2) Dynamic mechanical analysis (DMA) showed that the storage modulus and loss modulus of NR composites increased after adding MWCNTs and SiO\({}_{2}\), while the loss factor decreased. This indicates that the stiffness of MSNR increased, and the molecular chains within NR were restricted, resulting in a higher interfacial bonding strength. (3) The dispersion performance of the MNR, SNR, and MSNR composites was analyzed using a rubber process analyzer (RPA). The Payne effect of the MSNR composite was lower, indicating better dispersion. (4) The fracture surface morphology of the MNR, SNR, and MSNR composites was analyzed using scanning electron microscopy (SEM). The synergistic effect between MWCNTs and SiO\({}_{2}\) in the MSNR composite resulted in a uniform distribution of all fillers within the NR matrix, thereby improving the overall performance of NR. (5) Molecular dynamics (MD) simulations were used to calculate the MSD, FFV, and binding energy of the composites. The results showed that MSNR had the lowest MSD and FFV and the highest negative binding energy, indicating that the dual-component fillers restricted the movement of NR molecular chains and exhibited better interfacial bonding with the NR matrix. These simulation results were consistent with the experimental findings. (6) The hysteresis area of the first cycle stress-strain curve of MSNR was the largest; a larger hysteresis area usually means that the material loses more energy after a force is applied, resulting in a larger hysteresis loss. The results show that MSNR has a weak  
Figure 8: Image of molecular dynamics simulation. **(a)** NNR, **(b)** SNR, **(c)** MNR, and **(d)** MSNR. elastic recovery compared to the other three composites. This is due to the fact that NR is inherently viscoelastic. In future work, we will focus on the difficult task of reducing the viscoelasticity of NR composites to minimize the hysteresis loss. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/molecules30020349/s1](https://www.mdpi.com/article/10.3390/molecules30020349/s1)]([https://www.mdpi.com/article/10.3390/molecules30020349/s1](https://www.mdpi.com/article/10.3390/molecules30020349/s1)), Figure S1: Stress-strain cyclic curve of NNR, MNR, SNR and MSNR; Figure S2: Free volume model of NNR, MNR, SNR and MSNR. Figure S3: Molecular dynamics model: (a) NR; (b) MWNCT; (c) SiO\({}_{2}\) and (d) different atoms. Table S1: Definitions of abbreviation used in this study; Table S2: Comparison of mechanical properties. Table S3: DMA performance comparison. Table S4: The formula of the composites. Z.F. : Conceptualization, Methodology, Investigation, and Writing--Original draft. H.Z. : Conceptualization and Supervision. B.H. : Investigation and Data analysis. H.C.: Investigation and Data analysis. Y.Y. : Methodology, Writing--Review and Editing, and Funding acquisition. All authors have read and agreed to the published version of the manuscript.