Natural rubber (NR) is used in a wide range of industrial applications such as automotive tires, drive belts, and packaging due to its unique molecular composition and structure [1–4]. NR has a highly cis-structure with a small amount of trans-structure in the molecular chain structure. Tanaka in 1989 used 13C-NMR to determine the molecular chain structure of NR, which consists of thousands of cis-1,4-isoprene units, 2 to 3 trans-1,4-isoprene units, and dimethylallyl linkages [5]. NR contains a large amount of cis-1,4-polyisoprene and about 2% trans-structure [6].
MD simulation is a technique for modeling the properties of materials at the molecular scale. Simulation methods are used to elucidate the laws governing the motion of particles in time and space due to interacting forces in a system. As a first step, we must create models of the forces and laws of motion of the particles in the system, relating the microscopic inter-particle forces to the theory of Newtonian mechanics, determining the form of the inter-particle interactions and the laws governing the motion of the particles; we can then use computers to calculate the trajectories of collections of particles to determine their static and dynamic properties [7–10].
In 1956, Wainwright and Alder used MD to study the equation of the state of gaseous and liquid substances using the molecular hard balloon model. The results of the study showed that multidimensionality can guide practice theoretically and play an important role in solving many practical problems [11]. The first MD simulation of a real material model to predict the radiation hazards of diamond crystals was performed in 1959 by a group led by Vineyard in Brookhaven [12]. Rahman conducted the first MD simulation of a real fluid (hydrogen) using the continuous potential model in 1963 [13]. The time and space scales of early simulations were severely limited due to the computer's slow speed and inadequate memory.
Nowadays, computer technology is rapidly evolving, and the processing speed and storage space of computers are increasing, allowing people to solve complex material analysis problems using complex models [14–15]. People currently use the finite element simulation analysis method and the molecular simulation method as simple, reliable, and accurate computer simulation methods [16–18]. MD simulation methods have increasingly been implemented in the field of polymer materials since the beginning of the twenty-first century [19–21]. It is difficult to explain in detail due to the complex structure of polymer materials and the large molecular chain framework. To save calculation time, coarse-grained and all-atom models are commonly used to simulate polymer materials, and the Monte Carlo (MC) method is often used to create material models [22–23]. In addition to traditional experimental methods, MD simulation is an effective theoretical tool for studying the relationship between material structure and performance. It can not only explain experimental results, but it can also predict the effect of structure on material properties to some degree [24].
With the rapid advancement of computer science in recent years, MD simulation technology has grown in popularity in scientific research and practical applications. Researchers can quantify certain parameters that are difficult to obtain in experiments using MD simulations. Researchers can quantify certain parameters that are difficult to obtain in experiments using molecular simulations [25–26]. For example, the fraction of free volume (FFV), solubility parameter (δ), and mean square displacement (MSD) for materials, were conveniently calculated by MD [27–29].
Using the methods of MD simulation, this research aims to predict the influence of the trans-structure in the NR molecular chain structure on the tensile stress of NR. In a uniaxial tensile simulation by building model-1 and model-2, the effect of trans-structure on the tensile stress of NR was analyzed based on MD simulation results. Provides theoretical guidance for the preparation of high-performance IR.