In Situ polymerization of isotactic polypropylene nanocomposites with metallocene catalysis

Abstract

The family of polyolefins are materials with a high demand, due to thermoplastics are structurally simpler and economical in their production and processing. Within the polyolefins, the commercial use of polypropylene began with the rise of the catalyzed reactions, in this way it was possible to control its specific conformation and with it, the final properties. In order to improve their properties, these materials are usually reinforced, specially with nanometric loads. So far, three methods have been developed for obtaining nanocomposites: In situ polymerization, melt intercalation and solution mixing. In order to solve the existing problems, in terms of charge dispersion, molecular weight control of the synthesized matrix and the complexity of the immobilization processes of the metallocene catalysts, this research uses In situ polymerization of polypropylene-Sepiolite, using the nanoclay as support of the catalytic system. This study proposes a method of immobilization that contemplates the use of the density of the polar groups that has the surface of Sepiolite, to fix the co-catalyst. In addition, the resulting polymerization process defines the reaction temperature as a variable which will provide a mechanism for controlling the molecular weights of the polypropylene. The proposed method has allowed the polypropylene to be added in its own synthesis process, besides controlling its structure in terms of its stereo-specificity and molecular weight, thus improving its final properties.

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