Flow channels with hyperbolic contraction geometries impart purely extensional flow along their centerline. Since extensional flow is potentially so important in improving the distributive mixing of composites, a series of screw elements has been developed that utilize hyperbolic flow channels as a means of imposing extreme elongation rates over short distances. These screw elements effectively act as static mixers within the barrel of a twin-screw extruder, riding along bearings on the screw axes. Pure extension is achieved through specifically designed channels that have a uniform width contraction for a given length. Simulations have shown that such flow channels on twin-screw extruder elements display this linear velocity increase (pure extension), with extension-dominated flow taking place across the channel width. It is expected that these mixing elements will dramatically increase the level of distributive mixing obtainable in twin-screw extrusion.