The design and performance of a new miniature mixer for specialty polymer blends and nanocomposites

A novel miniature mixer called the "Alberta Polymer Asymmetric Minimixer" (APAM) was designed, built and tested. In this study, polymer blends and nanofiber composites were compounded using a total of approximately 2 grams per sample. This mixer has a unique, asymmetric design consisting of a varying clearance between the rotor blade tips and the cup wall, enabling the material to be squeezed, stretched and kneaded in high shear and converging zones. Unlike the few other miniature mixing devices that are commercially available, the APAM has a combination of good mixing capability and complex flow modes required for dispersive flow, and requires minimal sample mass. In this work, the final morphology of nonreactive blends created in the APAM was similar to that obtained in an internal mixer and in a twin-screw extruder, and was much finer than that obtained in a MiniMAX(TM) mixer. The final morphology in reactive blends was comparable for all the mixers. The dispersion of nanofibers is uniform for the nanocomposites blended in the APAM and comparable to the dispersion obtained in the internal batch mixer, whereas for the MiniMAX(TM), the nanofibers remained in bundles and were not wetted by the matrix polymer.