Coextrusion of tpu and BaSO4 filled medical-grade TPU

Abstract

Coextruded products for the medical device industry, involving layers of filled and unfilled polymers, are difficult to fabricate, especially due to the various degradative processes taking place especially when various stabilizers are not included in the medical-grade formulations. Significant differences in the degradation behavior and the subsequent rheological behavior of unfilled and BaSO4 filled TPUs generally give rise to severe fluctuations at the interfaces and poor coextruded products. It is shown here that the shear viscosity values of the filled and unfilled TPU need to be matched under the extrusion conditions to obtain acceptable coextruded medical products.