Preparation and characterization of polypropylene/montmorillonite nanocomposites

CORA O. ROHLMANN; LIDIA M. QUINZANI; MARCELO D. FAILLA.

Brasil

Congreso; Empromer ?05. 2nd Mercosur Congress on Chemical Engineering; 2005

Polymeric nanocomposites (PNC) are a type of reinforced materials prepared with low concentrations of particles that have at least one dimension in the nanometer scale. It has been observed that PNC exhibit improved mechanical, thermal and barrier properties without altering significantly the density and optical properties of the polymer. The aim of the present work is to prepare and study nanocomposites based on polypropylene (PP) and montmorillonite (MMT) with the intention to contribute to better understanding the relationship between the structural characteristics of the PNC with its properties and processing methods.  This study involves the analysis of the microstructure of the composites and the effect that the dispersion, shape and orientation of the particles have on the thermal, mechanical and rheological properties. The materials used in the study are an isotactic PP from Petroquímica Cuyo S.A.I.C., a polypropylene grafted with maleic anhydride (PPg) from Uniroyal Chemical Co., and a natural MMT from Minarco S.A.  The MMT, which is a laminated alumino-silicate, is treated with octadecylamonium chloride to produce an organophilic clay.  The presence of small amounts of PPg and of a modified MMT improves the interaction between the hydrophobic PP and the hydrophilic clay.  The components are mixed in a molten state using a Brabender Plastograph.  Transmittion electron microscopy (TEM) and X-ray diffraction are used to characterize the nanocomposites morphology.  The thermal properties are evaluated by differential scanning calorimetry and thermogravimetric analysis.  The dynamic moduli of the solid and molten materials are obtained in a dynamic rotational rheometer as a function of temperature and frequency.