Morphology features and effects of particle size and composition of the disperse phase on the impact properties have been studied for the blends of isotactic polypropylene (PP)/ethylene‐propylene‐diene terpolymer and (EPDM)/linear low‐density polyethylene (LLDPE). The blend components were mixed in a twin‐screw extruder, press molded, and analyzed by scanning electron microscopy, SEM (fractured and toluene etched samples), and by transmission electron microscopy, TEM (RuO4 stained samples). TEM was most effective for the identification of component distribution and particle size measurement. An increasing degree of LLDPE and EPDM interpenetration was observed with the PE content. Not one case of a neat component separation was detected. LLDPE addition improves the EPDM dispersability, affecting mainly the larger particles. The impact properties at room temperature were especially dependent on the rubber content, whereas at low temperature the particle diameter appears to be the controlling parameter. The affect of LLDPE on blend toughness is more evident in the latter case.

The molecular structure of a polypropylene (PP) blend, of the type referred to commercially as “impact polypropylene copolymer” (IPC), was studied and a procedure to determine its main component composition developed. The constituent species of the whole IPC, PP and ethylene‐propylene copolymers (EPC), were separated by step elution analytical Temperature‐Rising Elution Fractionation (TREF). The corresponding fraction compositions were calculated as percent areas of the fractogram. Since the EPC elution signal overlaps that of the homopolymer, an independent determination of pure PP fractions has to be performed in order to subtract its effect from the IPC profile. Thermal and molecular analysis of the recovered fractions by Differential Scanning Calorimetry (DSC) and Size Exclusion Chromatography (SEC), and spectroscopic analysis by FTIR and 13C‐NMR supported the necessary assumptions for a good estimation of the composition.

Polypropylene (PP) blends, commercially known as “impact polypropylene copolymers” (IPC), are produced by a sequential gas phase polymerization process. The final product is a complex mixture of polypropylene (PP) and a range of ethylenepropylene copolymers (EPC) with different ethylene contents. In the present work, the composition of three different IPC was estimated by performing a step elution mode Analytical Temperature Rising Elution Fractionation (TREF) separation. The recovered fractions were analyzed by Differential Scanning Calorimetry (DSC), Size Exclusion Chromatography (SEC) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology was examined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Amorphous EPC were isolated in an independent way in order to perform a more careful characterization. The distinct particle size and shape of the dispersed phase for different IPC was interpreted in terms of the molecular characteristics of the blend components and their compositions.