Polymer Blending Mechanisms in a Single Screw Extruder

5 Polymer Blending Mechanisms in a Single Screw Extruder 

Overall this indicates that a polymer blend of small dispersed droplets in a continuous phase cannot be produced using a single screw extruder if the viscosity ration of the disperse phase to the continuous phase is greater than 4. Practical experience indicates that this cannot be true. There is also the question as to how droplets are formed in the first place.  

Blends were prepared using 20wt% amorphous PA as the disperse phase in PS. Viscosity ratio of PArPS was about 14 well above the limit of about 4 for laminar shear mixing. Samples were mixed for times varying from 1 to 15 minutes and examined by scanning electron microscopy (SEM) following solvent extraction of the PS. 

2) Areas of sheets and ribbons - some with holes. 

Within another half minute there were many particles resulting from disintegration of the lace structure and by seven minutes nearly all disperse phase material was spherical particles. 

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