Powder blender high-shear

Tumble blenders also impart shear forces to the powders being blended as slip planes form between the walls of the blender and layers of the blend. The amount of shear force is often low for small-scale blenders, but can increase with increasing scale of the blending container. Because they tend to provide gentler blending and have less of an affect on the particle size of the materials being blended (compared to high shear mixers),... 

Table 11.16 shows the composition of a PVDF blend for foam fabrication. This recipe was mixed in an intensive power blender to produce a homogeneous powder blend which was then melt blended in a high shear twin screw extruder at 200 rpm and a temperature of 200°C. Pellets were produced by extruding the melt into water and chopping the quenched extrudate. The foamable blend was extruded, through a 25 mm extruder, according to the conditions given in Table 11.17. A comparison of the properties of foamed and solid PVDF wire insulation is presented in Table 11.18.

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