Abstract: The invention provides a thermoplastic polyurethane elastomer which contains a blend of polyurethane resins and is suitable for use in the form of tubing. The blend has a tensile strength of more than 7000 psi and an ultimate elongation greater than 200%. The blend contains about 50% to about 80% by weight of an elastomeric polyurethane resin having a hardness in the range of about 60 to 70 Shore D units. The blend additionally contains about 20% to about 50% of a relatively rigid polyurethane resin having a hardness of about 10 units more than the elastomeric resin. The invention also provides methods for using and methods for manufacturing tubing fabricated from the thermoplastic polyurethane elastomer. Preferred extrusion conditions are described.

Abstract: Medical tubing is extruded from a composition of a divalent metal ionomer, polyamide and polyurethane, preferably in the ranges of 60-80% of ionomer, 10.gtoreq.25% polyamide and 10-20% polyurethane. After extrusion the tubing may be sterilized with ethylene oxide or gamma irradiation. The tubing is substantially kink-resistant and the degree of stiffness and mechanical strength can be adjusted by varying the amount of polyamide and polyurethane so that the tubing can efficiently function as a catheter.

Abstract: A plasticating extruder screw incorporates two or more screw configurations into a single screw. This is accomplished with two or more parallel channels in which each channel is designed to a different set of materials and performance requirements reflecting the range of the materials to be processed. The extrusion screw in fact represents two or more screws in a single screw in which each performs its function independently of the other. Thus, each channel in this screw differs from the others in critical design parameters such as compression ratio, length and depth of its feed, transition and metering zones. This multiconfigurational design feature may occupy part or the entire length of the extruder as dictated by the specific characteristics of the materials to be processed. A mixing and stabilization zone placed at or near the entrance of the metering zone of the screw provides for melt flow interaction and equilibration between channels.