How to Achieve Quality Polymer Blends by a New Extrusion Technique
Abstract The flow patterns of a striation through a Cavity Transfer Mixer was demonstrated. These were seen to take an optimum path and action to achieve exponential efficiency of mixing. The striation was seen to turn through 90° before being cut in successive segments, deposited in the next cavity row, and drawn out perpendicular to the original direction of shear. The effectiveness of the CTM is a result of the regular turning and cutting action which had been predicted and which has been demonstrated. Factory trials have shown that polymers and masterbatched materials can be blended efficiently in a CTM unit and that off-specification materials can be processed without further reduction in viscosity. Thermoplastic rubbers can be processed on rubber extruders with plain pumping screws fitted with CTM units to blend color or ingredient masterbatch without prior mixing. We would conclude that all the above advantages are secondary to the main advantage of “temperature blending” which the Cavity Transfer Mixer will achieve and which we have reported in our previous paper.