Ultrasound-aided extrusion process for preparation of polypropylene--clay nanocomposites

Two methods for the fabrication of polypropylene/clay nanocomposites using a continuous ultrasound assisted process are compared. In the first approach, a two-stage process was implemented. The nanocomposites were prepared by using a corotating twin-screw extruder followed by a single-screw extruder equipped with an ultrasonic die attachment. In the second method, a single-stage process was used. The nanocomposites were compounded by using a single-screw extruder with mixing elements and an ultrasonic die attachment. Two regimens of feeding were realized, namely, starved and flood feeding. The gap size in the ultrasonic treatment zone was varied. Die pressure and power consumption were measured. Similarities and differences of nanocomposites obtained by these two methods are discussed on the basis of their rheological and mechanical properties and their structural characteristics