Synthesis of polymeric materials

New catalytic system development for bimodal polyethylene synthesis

The goal of this research line is the synthesis of bimodal polyethylene through new heterogeneous catalytic systems able to promote bimodal polymers in a one-step polymerization. These strategies could be able to produce materials with characteristic of commercial products, such as polyethylene for pipe applications. Considering the experience of our research group in mesostructure catalysts, several strategies will be employed to modify the catalytic system. According to this, variations porosity and modifications in superficial chemical compositions of carrier will be carried out. The preparation of hybrid chromium-metallocene catalysts will be another alternative to modify the support.

New heterogeneous catalytic processes development for bimodal PP synthesis

Metallocene catalyst enable production of polypropylene (PP) having narrow molecular weight distribution. However, for numerous applications wider or bimodal molecular weight distribution are required. An attractive and economical route is to use two metallocene precursors simultaneously yielding a PP mixture consisting of the polymer fractions produced by the different metallocenes individually in a single reactor, instead of the traditional staged process. To replace the conventional heterogeneous Ziegler–Natta catalysts used in industrial slurry and gas-phase processes, metallocene catalysts have to be immobilized in a suitable carrier. Considering the experience of our research group in mesostructured materials, several strategies will be employed to support metallocenes catalysts.

Heterophasic polypropylene synthesis

In order to increase the applications of polypropylene and polyethylene, numerous processes of polymerization in several stages have been developed. So, one of the most important procedures is the synthesis of heterophasic (HECO's) or high impact polypropylene (HIPP). These are mixtures of homopolymer and bipolymers. These block copolymers are constituted by two phases a matrix of isotactic polypropylene homopolymer and another one of ethylene / propylene (EPR) with high comonomer content, randomly distributed and dispersed uniformly within the matrix. This composite reaches a high impact resistance at low temperatures, higher than polypropylene, this characteristic gives high versatility to the final material.