In the development of a new polymer blend aimed at enhancing impact resistance, which combination of processing conditions and polymer types would most likely lead to optimal phase separation and improved mechanical properties?

Blending a rigid polymer such as polycarbonate with a rubbery component like SEBS (styrene‑ethylene‑butylene‑styrene) and adding a small amount of a compatibilizer (e. g. , a block copolymer) creates a phase‑separated microstructure that dissipates impact energy. Processing the blend at a temperature above both polymers’ melting points (around 260 °C) and then cooling slowly allows the two phases to grow to an optimal size—too small and the rubber is ineffective, too large and the blend becomes brittle. The resulting interpenetrating network gives high toughness while maintaining stiffness.