Detecting blend morphology development during melt blending along an extruder

Online sampling experiments were carried out to investigate the development of immiscible polymer blend morphology along a single screw extruder using specially designed sampling devices. The morphology of molten blend samples collected at different locations was observed by scanning electron microscopy (SEM) and evaluated both qualitatively and quantitatively. Two polypropylene/polyamide-6 blends with different viscosity ratios, one about 0.1 and the other about 1.0, were selected to investigate the influence of the viscosity ratio on the morphology development. Experimentally observed results showed that, for the blend with a smaller viscosity ratio, major morphological changes occurred during the initial softening stage of blending. For the blend with a larger viscosity ratio, the extended striations are transformed to a droplet morphology gradually along the screw. It was demonstrated that it is possible to detect the morphology development along the extruder screw nearly in real time with the sampling device assembled in a single screw extruder. Information about the dynamics of morphology development in the extruder can be obtained.