| Rubber materials are widely applied in industrial science and technology,aerospace,petrochemical and advanced technology due to their excellent mechanical properties,strong elasticity and low density.However,single rubber materials often fail,and the reinforcement effect of traditiona l reinforcement materials on rubber matrix is not obvious.Carbon nanotubes have gradually replaced traditional reinforcement materials due to their low cost,unique structure and excellent thermodynamic properties.The rubber material modified by carbon n anotube blending has mechanical and electrical response properties,which can be used for sensing and monitoring.At present,the main research methods for the mechanical properties of rubber materials are still based on the continuous theory calculation.With the development of the times,the theory of molecular dynamics has gradually improved.Through molecular dynamics simulation,the trajectory of each atom can be accurately calculated,and many microscopic details can be found in the process of atomic motion,which provides strong support for theoretical calculation and experimental research.This has also become a new method for simulation analysis of carbon nanotube modified rubber materials.The purpose of this paper is to study the tensile propertie s of natural rubber and its composites from the microscopic point of view,and to explore the microscopic mechanism of carbon nanotube reinforced rubber matrix.Firstly,natural rubber models with different polymerization degrees were established.Through the calculation of microscopic inherent characteristics and mechanical parameters and tensile simulation,it is found that a smaller degree of polymerization can make the interior of the model more compact.However,in the tensile process,the short molecu lar chain is more likely to break,and the yield stress of the model decreases.Considering the above factors,the model is established based on the degree of polymerization of 40.In this paper,the molecular system model of vulcanized natural rubber composites with different carbon nanotube contents was established by writing vulcanization scripts,when the content of carbon nanotubes is 8 wt%,the composite had the best mechanical properties and the largest binding energy,when the content exceeds 8 wt%,the agglomeration phenomenon is obvious.The high strength of carbon nanotubes and the binding energy between carbon nanotubes and matrix are the main reasons for improving the mechanical properties of composites.On this basis,three models of carbon nan otube modified rubber materials with different chirality were further established,by simulating the drawing behavior,it is found that the reinforcing effect of helical carbon nanotubes is slightly stronger than that of armchair carbon nanotubes,and the reinforcing effect of serrated carbon nanotubes is the worst.The calculated results show that the helical structure has stronger interface energy,which proves that the interface energy is positively correlated with the chiral angle of carbon nanotubes.Finally,by comparing the natural rubber model and the vulcanized natural rubber model,it is analyzed that the vulcanization has enhanced the microscopic inherent characteristics of different composites.By comparing the tensile deformation characteristics of composite models with different carbon nanotube lengths at the same content,it is found that the short carbon nanotube modified composite has a more compact structure and higher stiffness,while the long carbon nanotube modified material s hows a higher ductility. |
