MALEIC ANHYDRIDE GRAFTED POLYPROPYLENELAYERED HYDROTALCITE MASTER BATCH AND RESULTANT NANOCOMPOSITES PREPARED BY MELT PROCESSING: STRUCTURE CHARACTERIZATION AND MECHANICAL PROPERTIES

Polypropylene/hydrotalcite nanocomposites were studied in respect of processing methods and the effect of filler, structure and the resultant thermomechanical properties. Compared to the commonly used montmorillonite layered silicate less attention has been reported to the hydrotalcite nanofiller up to now. A master batch with about 11 mass% filler content was obtained by melt processing, using maleic anhydride grafted polypropylene (PP-g-MAH) to enhance the matrix-filler coupling interactions via polar groups. In addition, a composite with about 3 mass% filler content was prepared from the master batch by adding an impact modified PP/PE copolymer which was then injection moulded. TEM and SEM on the master batch exhibited a good dispersion of the hydrotalcite particles in the PP-g-MAH matrix with particles being in the nanometre scale, but no individual layer dispersion of the hydrotalcite was achieved. DSC analyses on the master batch exhibit an increase in the crystallization rate due to the presence of the hydrotalcite filler, whereas the degree of crystallinity was significantly decreased. Tensile and DMA experiments prove the reinforcing character of the filler. The master batch, however, is brittle with no plastic deformation behaviour. In comparison with the master batch, the composite is a tough material with a 4.3 % yield strain and a strain at break of about 8.8 %.