ANALYSIS OF MORPHOLOGY DEVELOPMENT OF IMMISCIBLE BLENDS IN A TWIN-SCREW EXTRUDER

Blending processes are primarily carried out in corotating intermeshin g twin screw extruders. Because the knowledge about morphology develop ment in such extruders is limited methods to obtain a desired morpholo gy are based on empirical values and screening experiments. For the an alysis of morphology evolution, a new special sampling device was deve loped which enables melt sampling in time periods of less than 10 seco nds. With this technique integrated in an intermeshing corotating twin screw extruder, ZSK 40, it is possible to detect morphology developme nt along the extruder screw nearly in real time. The performance of th e developed method was verified by observation of morphology developme nt in a polypropylene/polyamide-6 blend system along a screw section. A difference in morphology development caused by a variation of the sc rew rotational speed was observed. Furthermore, drop deformations in p artially filled screw sections could be detected. (C) 1997 John Wiley & Sons, Inc.