| Abstract: | Blends of styrene-butadiene-styrene (SBS) triblock copolymer with isotactic polypropylene (iPP) or maleic anhydride–grafted polypropylene (MAP) were prepared in a twin-screw extruder. Static and dynamic experiments at room temperature in previous works showed that the added homopolymers have a significant influence in the improvement of the general mechanical properties of the SBS when the homopolymer is the dispersed phase. Our aim was to study the reinforcing effect as a function of temperature. When the glass transition of the polystyrene blocks in the SBS is approached (40°C–50°C in static experiments), there is a significant worsening of the failure properties, as well as a profile change in the stress-strain plot. If a reinforcing hard phase is added, these changes can be decreased. The temperature dependence of the reinforcing effect of the added homopolymer was evaluated with the analysis of tensile experiments in terms of various theoretical models. A modified activation energy model with temperature-dependent parameters was used to describe the nonlinear regime and quantitatively compare the properties of the different blends with those of pure SBS. |
