Introduction

Rubber is a kind of polymer that can be natural or artificial and it’s an important material used in the tire industry, footwear, automotive accessories, health related products, among others. Natural rubber is obtained from latex, which is produced in many tropical plant species Almost all the world’s natural rubber production comes from the rubber tree (Hevea brasiliensis ) latex extraction, although many tropical plant species produce this material.
Natural rubber has some properties that make their use difficult. For example, in cold temperatures it becomes hard and brittle, while in higher temperatures it becomes soft and sticky. Due to this fact, Charles Goodyear started to research in 1839 the process called vulcanization. In this process, sulfur was added to the polymer causing its double bonds to break and forms sulfur bridges that bind the side chains, decreasing hysteresis, reducing permanent deformation and increasing elasticity .
From then on, studies began to be carried out on the addition polymerization reactions of dienic compounds, producing many types of synthetic rubbers. Depending on the type of monomer used to make the polymer, rubbers with different properties can be achieved.
The object of this study is the simulation of polymerization of 1,3-butadiene (the structure of the monomer can be seen in Figure 1), one of the most used elastomers on the rubber industry. Also called simply butadiene rubber (BR), it is predominantly based on cis-1,4 polybutadiene and its synthesis require a catalyst usually based on a transition metal, specially the lanthanide’s metals. In Table 1, it can be observed the different metals used in catalysts for performing polybutadiene and its respective microstructure. The structure of the polymer obtained from 1,3-butadiene indicates the addition occurs preferably in the -1,4 positions. Notably, the carbon chain still has a double bond. Although the isomer trans the most stable, when catalysts based on neodymium or titanium are used, the polymer chain tends to be formed by cis isomers.
Table Polybutadiene’s distribution microstructures with different catalysts .