Medical polyurethanes

These thermoplastic polymers are supplied as pellets; but also come in solution form. Please contact your dsm-firmenich representative to learn more.

Store our polyurethanes at 15-32°C (60-90°F) in a relatively dry, dark place (due to the hygroscopic nature of this material). If possible, the entire contents of a container should be used at one time. If this isn’t possible, you should put the remainder in a re-sealable container - ideally blanketed with an inert gas (such as dry nitrogen).

Our polyurethanes can be processed using many thermoplastic methods: including injection molding, extrusion and compression molding. Melt processing conditions are similar to conventional thermoplastic polyurethanes. For more information, download our TPU Extrusion Guide and/or The DSM Injection Molding Guide.

• Filtered solutions of the thermoplastic polymers are suitable for solvent bonding, dipping, coating, spraying, and related solvent-based conversion methods. For more information, contact our team of experts.

Proper drying of the pellets is an important first step to ensure efficient thermoplastic processing and the production of high-quality parts. A desiccant-bed-type dehumidifying hopper dryer is recommended, with an inlet air temperature of 80o – 95o C (180o – 200o F) for Bionate®, Bionate® II, CarboSil®, Elasthane®, and PurSil® polyurethanes. For ATPU grades the inlet air temperature should be set to 60o – 80o C (140o – 176o F).  

• Drying to approximately 0.01-0.02% moisture can usually be accomplished in 8 to 12 hours. However, the time will depend on the efficiency of your dryer and the amount of material to be dried. The harder durometer materials (e.g. 55D & 75D) may need a drying temperature and time at the higher end of the recommended range. 
• The moisture content of medical polyurethanes should be measured by a moisture analyzer immediately before each use. After drying, the material may need to be manually separated (using a gloved hand) before melt processing in order to prevent the throat of the extrusion or injection molding equipment becoming blocked. For injection molding, a dew point reading of approximately -20 to -40°C (-5 to -40°F) on the return air hopper is also a good indicator that the material is ready for processing. Note: We do not recommend over-drying or re-drying polyurethanes as this may cause sub-optimum processing and gels.

We recommend Ethylene Oxide (EtO) for sterilizing devices made with polyurethanes, based on published references. Our testing indicated that EtO sterilization has no noticeable effect on the mechanical properties of polyurethane parts. Gamma radiation is another sterilization method for parts made from our medical polyurethanes. In fact, when tested, polyurethanes from dsm-firmenich Biomedical showed no changes in mechanical properties when sterilized by gamma irradiation up to 45 KGray (1 Gray= 1 Joule/Kg). We do not recommend using steam sterilization; although other methods of sterilization may be appropriate, depending on the design of the part. Ultimately, device manufacturers are responsible for verifying the impact of the sterilization process on their products’ performance.