Precision Microprofile Extrusion with a Wall Slip Condition

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

The research objective of this award is to develop and investigate a novel precision microprofile extrusion process, the basis of which uses a field-induced material transport mechanism for creating a conformal fluidic layer on the microextrudate. To create a thin conformal fluidic layer, a polymer blended with a small amount of miscible low-molecular-weight or oligomeric additive is extruded through a long die channel, causing enhanced phase separation to occur. This shear-induced phase separation, in turn, causes the low-molecular-weight fluid to migrate to the die surface, thus forming a conformal fluidic layer and creating a wall-slip condition for the polymer extrudate. Due to wall slip, the flow stresses and thus the amount of die swell are minimized. Furthermore, due to the inherent miscibility of the fluidic layer with the polymer extrudate the surface tension effect is greatly reduced or eliminated. The main research activities will be 1) to demonstrate the technical feasibility of this novel microprofile extrusion process, 2) to gain a fundamental understanding of field-induced phase separation in microprofile extrusion and, 3) to formulate a predicative model for this new process. Successful complication of this research will lead to a novel manufacturing process for precision microprofile extrusion. Precision microprofiles offer unique functions (e.g., enhanced surface activities, diffractive effects, wave transmission efficiency, etc.) that cannot be realized by their circular counterparts. Although precision microprofiles are highly desirable in the emerging biochemical, biomedical and telecommunication industries, a capable process for fabricating them is yet to be developed. The new process would therefore fill a technical gap and create new market sectors for a wide variety of applications. Moreover, the knowledge gained on the enhancement of field-induced phase migration would be particularly useful in the development of other innovative processes, potentially in the areas of coating, lubrication, and selective surface modification.