Supertoughness in poly sulfone/poly (ethylene-octene) blends

Poly(sulfone of Bisphenol A)(PSU) based blends were obtained by melt blending PSU with up to 15 wt.% poly(ethylene-octene) either modified with maleic anhydride (mPEO) or not (PEO). The dispersed particle size was small and similar in blends with PEO or mPEO. These facts indicated respectively that the interfacial tension was low and the lack of compatibilizing effect of mPEO. Some preferential presence of PEO in the outer surface of the specimens was observed, and was attributed to the large viscosity difference between the two components of the blends. This had no effect on the modulus of elasticity, but speeded up both the yield stress and ductility decreases at rubber contents above 3.25 wt.%. However, despite the immiscibility of the components, and thanks to the small particle size of the blends, super-toughness was attained in the unmodified PSU/PEO blends. This was at PEO contents (3.25 wt.%) at which the modulus, yield stress and ductility of the blends were almost as good as those of pure PSU. It appeared that a change of the chemical nature of the rubber did not influence by itself.