Preparation and of Polypropylene/Montmorillonite Nanocomposites

CORA OTILIA ROHLMANN; LIDIA MARÍA QUINZANI; MARCELO DANIEL FAILLA

Río de Janeiro, Brasil

Congreso; 2nd Mercosur Congress on Chemical Engineering and 4th Mercosur Congress on Process Systems Engineering (ENPROMER?05); 2005

Escola de Química, UFRJ - Centro de Tecnologia, Rio de Janeiro ? Brazil

The aim of the present work is to prepare and study nanocomposites based on polypropylene and montmorillonite to contribute in the understanding of the relationship between the structural characteristics of these composites and their properties. Two montmorillonites are considered in the study, one obtained from an Argentinean bentonite and modified with octadecylammonium chloride, and an organophilic commercial one. Small amounts of grafted polypropylene are added to the mixtures to improve the interaction between the hydrophobic polypropylene and the hydrophilic clay. The components are mixed in a molten state using a thermoplastic mixer. Electron microscopy and X-ray diffraction are used to characterize the clays and the composites morphology. The thermal properties are evaluated by differential scanning calorimetry and thermogravimetric analysis, and the dynamic moduli of the composites are obtained in a dynamic rotational rheometer as a function of temperature and frequency. The obtained results show that the use of modified clays in the composites retards the beginning of the degradation and improves the thermal stability. The crystallization temperature of the composites decreases when the concentration of grafted polypropylene in the mixture increases, and increases when the concentration of modified clay increases. Furthermore, the elastic modulus of the composites are, in general, larger than that of polypropylene and an increase of the modulus at low frequencies it was observed as the temperature increases.