Formulating polymer blends is of vital scientific and industrial interest because of their low cost and the possibility of producing new materials with tailored properties. In this research, polypropylene (PP)/acrylonitrile–butadiene–styrene (ABS) polymer blends were prepared using styrene-ethylene-butylene-styrene (SEBS) and styrene-ethylene-propylene (SEP) copolymers. The polymer blends were extruded and injection molded to evaluate the mechanical, rheological, thermal, and thermomechanical properties, infrared spectroscopy, and morphology. Incorporating SEBS and SEP copolymers into the PP/ABS blend increased the torque and reduced the melt flow index, indicating higher viscosity than the PP/ABS base system. As a result, improved compatibility of PP/ABS/SEBS and PP/ABS/SEP blends was achieved, thereby improving the mechanical properties of PP/ABS. However, the SEBS copolymer was more effective. Compared to neat PP, the PP/ABS/SEBS blend with 15% SEBS showed increases in impact strength, elongation at break, and heat deflection temperature (HDT) of 87%, 107%, and 7%, respectively. In addition, the elastic modulus and Shore D hardness were in line with neat PP, and thermal stability measured through thermogravimetry exceeded that of PP by 8 °C. Evidence of fractured ABS particles in the PP matrix was seen in the scanning electron microscopy (SEM) morphology, suggesting that SEBS migrated to the interface. SEBS also remained dispersed in the PP matrix, as confirmed by selective phase extraction, which favored a synergic effect of properties in the PP/ABS/SEBS blend (70/15/15%). This blend offered potential for applications such as toys, furniture accessories, packaging, and housewares.
