Polypropylene/polyamide-6 and polypropylene/metallocene polyethylene blends containing 2.5 phr
of organophilic modified montmorillonite were prepared in a twin-screw extruder followed by
injection molding. In order to compare, blends without layered clay were also made. Styreneethylene-
butylene-styrene copolymer and polypropylene grafted with anhydride maleic were used
as compatibilizers in the ternary blends and in the PP nanocomposite preparation, respectively. The
presence of tactoids, intercalated and exfoliated structures was observed by TEM in some of the
samples containing layered clay and modified PP materials. Results showed that the compatibilized
blends prepared without clay are tougher than those prepared with the nanocomposite of PP as the
matrix phase and no significant changes in tensile moduli were observed between them. However,
the binary blend with a nanocomposite of PP as matrix and metallocene polyethylene exhibited
better tensile toughness and lower tensile modulus, than those prepared with a nanocomposite of PP
and polyamide-6 as dispersed phase. These results are related to the degree of clay dispersion in the
PP and to the type of morphology developed in the different blends. Differential scanning
calorimetry (DSC) showed that blends with a finer and homogeneously dispersed morphology
determined by SEM, the PA component exhibited fractionated crystallization exotherms in the
temperature range of 159-185°C. Also, nucleation of the PP component by PA phase and/or the
layered clay was observed in the blends with PA as dispersed phase.
Physical Aging Behavior of a Glassy Polyether
