| Abstract: | A set of blends of styrene–butadiene–styrene triblock copolymer (SBS) and isotactic polypropylene (i‐PP) in a composition range 0–100 % polypropylene by weight was prepared in a twin screw extruder. The morphology of the blends has been studied by transmission electron microscopy. The blends present phase separation. Dynamic mechanical measurements show an improvement of the mechanical properties of SBS when i‐PP is the dispersed phase. This reinforcing effect can be observed even at high temperatures when i‐PP is in the rubbery state. The mechanical properties of the blends have been interpreted using Takayanagi's block model. The melting and crystallization behaviour of the i‐PP in the blends has been studied by differential scanning calorimetry. The fractionated crystallization phenomenon has been observed in the blends where i‐PP forms the dispersed phase. The results are consistent with the morphology shown by the blends, in particular, with its phase inversion, which occurs at a composition near to 50% i‐PP. © 2000 Society of Chemical Industry |
