Toughened blends of polystyrene and ethylene-styrene interpolymers

Ethylene-styrene interpolymer (ESI) resins prepared using a constrained geometry catalyst were found to make tough blends with a polystyrene (PS) resin, with the toughening effect dependent upon the relative proportions of ESI and PS resins. At low levels in the blend, an ESI resin forms dispersed micro-domains of sub-micron size in polystyrene. At 40 wt % of styrene, an ESI resin makes a co-continuous blend that is both stiff and ductile. This toughening effect increases as the styrene content in the ESI resin increases, peaking at approximately 70 wt % of styrene.