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 .