Medical-Grade Polyurethanes, from Wound Care to Permanent Implants

MD&M East 2012 Event Coverage

Tony Walder, manager of technology, thermedics polymer products, for The Lubrizol Corp. (Wickliffe, OH) will present “Medical-Grade Polyurethanes, from Wound Care to Permanent Implants” at the MD&M East conference program on Monday, May 21. Lubrizol specializes in additives, ingredients, and compounds optimized for the healthcare and other industries.

MPMN: What characteristics or properties of medical-grade polyurethanes make them potentially more desirable for certain applications than other polymers?

Because of such characteristics as versatility and biocompatibility, polyurethanes are suited for use in a range of medical applications.

Walder: Polyurethanes feature characteristics that may be useful in a variety of medical application, including biocompatibility, processing ease, strength, and versatility. Available medical-grade polyurethanes currently range from soft elastic Shore durometer 62A to rigid glass-filled versions featuring a flexural modulus of 2,200,000 psi. Because of the materials’ versatility, polyurethanes can compete with silicones as well as metal replacements.

Soft elastomeric polyurethanes specifically are known for their strength and can be up to four times stronger than other elastomers, such as silicone. This strength allows for the development of tubing with thinner wall thickness. A tube can have the same outside diameter, for example. But because the wall is thinner, the inside diameter is increased for improved fluid flow.

Furthermore, biocompatibility of medical-grade polyurethane also means that it may be useful in implants for different areas in the body, lasting from minutes to the lifetime of a patient. The versatility of polyurethanes allows for various characteristics to be highlighted as required for the application. Some of these characteristics include abrasion resistance, softening, chemical resistance, and diffusion rates of moisture or gases.

MPMN: What processing methods are optimal for producing polyurethane parts or devices?

Walder: Thanks to ease of processing, thermoplastic polyurethanes may be processed using the common melt techniques of extrusion and injection molding. The extrusion process can be employed to make films, sheet, single-lumen tubing, profile tubing, and multimaterial tubing, among other products. Injection molding, on the other hand, is suited for building complex polyurethane parts of a device. To a lesser extent, thermoplastic polyurethanes can be dissolved in a solvent to coat a device or to create thin-film components such as balloons. Many polymers can be dissolved and cast into thin, complicated components as well.

MPMN: What’s next for medical-grade polyurethanes?

Walder: Lubrizol has many active programs aimed at developing unique polyurethanes that may be useful for medical devices. Areas of interest range from expanding existing product lines to meet the demands of new devices to developing new lines of materials.