THE EFFECT OF MATRIX MORPHOLOGY ON DYNAMIC-MECHANICAL PROPERTIES OF POLYPROPYLENE/LAYERED SILICATE NANOCOMPOSITES

In this work, the influence on the morphology and viscoelastic behavior of polypropylene/clay nanocomposites of clay, in combination with different crystallization rates applied in compression molding, is reported. By deconvolution of differential scanning calorimetry (DSC) melting endotherms, it was found that the slowly cooled samples had slightly higher melting temperatures, and the crystal dimensions decreased progressively with the clay content; while, in contrast, the presence of clay particles had no influence on the crystal dimensions in fast-cooled samples. Dynamic mechanical thermal analysis (DMTA) has shown that above the glass transition temperature, nanocomposites obtained by slow cooling exhibited better mechanical response compared to the fast-cooled samples. The value of dynamic modulus E' of slow-cooled samples increased by similar to 55 % with addition of only 1 wt% clay, which was attributed to the better reinforcing effect achieved during prolonged time of crystallization.