| Abstract: | The surface tension of atactic polystyrene (PS), isotactic poly(propylene) (PP) and PS/PP‐blends, and additionally the interfacial tension between PP/PS have been measured in the temperature range between 200 and 280°C using the pendant drop method. Within the temperature range studied, the surface tension decreased linearly with increasing temperature for all systems whereas the surface tension of neat PP is approximately 7 mN/m smaller than the value of PS. The interfacial tension between PS and PP is in the range of approximately 4 mN/m and this indicates a strong incompatibility. It results a heterogeneous PP/PS blend morphology. A significant increase of the surface tension of the blends as a function of composition is observed only when the PS content exceeds 60 wt.‐%. Furthermore, microscopic observations indicate that even if the bulk matrix material is PS, a thin layer of PP can be detected by atomic force microscopy on the droplet surface used for surface tension measurements. |
