Efficiency assessment of the SEBS, SEP, and SBS copolymers in the compatibilization of the PS/ABS blend

Polystyrene (PS)/acrylonitrile-butadiene-styrene (ABS) blends were processed in a corrotational twin-screw extruder and molded by injection. Styrene-(ethylene-propylene) (SEP), styrene-(ethylene-butylene)-styrene (SEBS), and styrene-butadiene-styrene (SBS) copolymers were tested as compatibilizing agents. The rheological, mechanical, thermal, thermomechanical, spectroscopic, and morphological behavior were reported. The type of compatibilizer greatly influences the final performance of the PS/ABS, considering that the incorporation of SEP formed a brittle and incompatible blend. In contrast, SEBS containing styrene terminal groups on both sides of the molecular structure, formed a PS/ABS blend with greater ductility. However, it has lower performance compared to SBS. The torque rheometry increased, and the melt flow index (MFI) reduced significantly for the PS/ABS/SBS blend, indicating more significant interaction between the components. As a result, gains of 113.7% and 379.3% in impact strength and elongation at break compared to PS. In addition, elastic modulus, tensile strength, Shore D hardness, and heat deflection temperature (HDT) maintained high results, confirming a synergistic effect of the PS/ABS/SBS blend. By thermogravimetry (TG), a gain of around 22 °C was observed in the PS/ABS/SBS blend for a mass loss of 50%, possibly due to acrylonitrile. Scanning electron microscopy (SEM) and atomic force (AFM) analyses reinforced these excellent results, revealing better compatibility and a more homogeneous distribution of ABS in the PS matrix in the presence of SBS. The PS/ABS/SBS blend results indicate potential applications such as electronics, air conditioning grilles, and toys.