MORPHOLOGICAL-STUDY ON THE EFFECT OF ELASTOMERIC IMPACT MODIFIERS IN POLYPROPYLENE SYSTEMS

The morphological effect of elastomeric impact modifiers has been studied in polypropylene systems by wide-angle and small-angle X-ray diffractometry, small-angle light scattering, light and electron microscopy and differential scanning calorimetry. It was established that the incorporation of an impact modifier altered the superstructure of the polypropylene matrix by decreasing the average size of spherulites through which the impact strength of the composite may be influenced. The changes in the mechanical and thermal properties are probably caused by the interphase between the amorphous elastomeric modifier and the polypropylene spherulites. The particle size of the dispersed elastomer is of vital importance in toughening of the amorphous polymer while in the crystalline resin, the changes in the superstructure also seem to be very important. Above Tg, the amorphous impact modifier acts as an energy absorber which markedly influences the crazing susceptibility of the polypropylene matrix. © 1979.