Mechanical behaviors of natural rubber viscoelastic materials based on molecular dynamics simulation

Taking natural rubber as an example, the effects of the material molecular chain polymerization degree p, the ambient temperature T and the loading rate R on the mechanical properties of viscoelastic materials under uniaxial tension conditions are investigated by using the molecular dynamics simulation method. The results show that the material stress increases with the increase of the polymerization degree and the loading rate, and decreases with the increase of the temperature. The material presents plastic characteristics at low temperature and high frequency. With the situation of R=108 s-1 and T=250 K, the material stress peaks are 79.8 and 99.8 MPa, respectively, when p=20, 40. As p=40, R=1010 s-1, under the conditions of T=100, 250 K, the stress amplitudes are 134.9 and 103.9 MPa, respectively. In the case of p=40, T=250 K, when R=109, 1010 s-1, the stress peaks are 122.7 and 134.9 MPa, respectively. In the loading process, the non-bonding potential energy plays a leading role in the total potential energy variation of the system. The molecular dynamics simulation method can be used to anaylze the effects of the molecular chain polymerization degree, the ambient temperature and the loading rate on the changes of the stress, the system energy and the free volume of viscoelastic materials. © 2021, Editorial Department of Journal of Southeast University. All right reserved.