Micro-compounding

Micro-compounding is the mixing or processing of polymer formulations in the melt on a very small scale, typically several milliliters. It is popular for R&D because it gives faster, more reliable results with smaller samples and less investment cost. Its applications include pharmaceutical, biomedical, and nutritional areas.

Overview
Micro-compounding is typically performed with a tabletop, twin screw micro-compounder, or -extruder with a working volume of 5 or 15 milliliters. With such small volumes, it is almost impossible to have sufficient mixing in a continuous extruder. Therefore, state-of-the-art micro-compounders have a batch mode (recirculation) and a conical shape.

The L/D of a continuous twin screw extruder is mimicked in a batch micro-compounder by the recirculation mixing time, which is controlled by a manual valve. With this valve, the recirculation can be interrupted to unload the formulation in either a strand or an injection moulder, a film device or a fiber line. Typical recirculation times are one to three minutes, depending on the ease of dispersive and distributive mixing of the formulation.

Benefits
Micro-compounding can now produce films, fibers, and test samples (rods, rings, tablets) from mixtures as small as 5 ml in less than ten minutes. By the small footprint, less lab space is needed than for a parallel twin screw extruder. One micro-extruder, developed to test the improvement of bioavailability of poorly soluble drugs or realize sustained release of dispersed or dissolved active ingredients, has options to easily fill and clean.