Influence of Polypropylene Reaction Time on the Clay Exfoliation Process by In Situ Polymerization

Abstract

In this work, polypropylene/clay nanocomposites were synthesized by In Situ polymerization employing an isospecific metallocene catalyst supported on montmorillonite clay, prepared under different conditions. The study aimed to evaluate the influence of the treatment process of catalyst supports, using different aluminum compounds, on their activity and polymer properties. They were evaluated in propylene polymerization at 60 °C under different reaction conditions, using toluene or hexane as reaction medium, and methylaluminoxane or its mixture with triisobutylaluminium as cocatalysts. Afterwards, another clay supported catalyst was prepared at a lower concentration of metallocene in order to produce a PP/clay nanocomposite with high concentration of clay. This is the first report showing the influence of the polymerization time, which was evaluated by taking aliquots during the reaction to determine its influence on the polymer properties during the exfoliation process. PP/clay-based nanocomposites were obtained with high concentration of exfoliated clay, showing mechanical and thermal properties superior to those of the homogeneous polypropylene.