Fact Sheet: HydroThane™ Hydrophilic Thermoplastic Polyurethanes
[In pdf format]

• We manufacture and market thermoplastic elastomeric hydrogels under the tradename HydroThane™. HydroThane™ is a generic family of polyurethane hydrogels, with each grade having its own specific water absorption characteristics.
  
  
• HydroThane™ is a family of super absorbent thermoplastic, hydrophilic aliphatic polyurethane elastomers, ranging in water absorption from 5% to 25% by weight, and is offered as a clear resin in durometer hardnesses of 80A & 93 Shore A. The outstanding characteristics of this family of compounds are the ability to rapidly absorb water, high tensile strength and high elongation. The result is a polymer having lubricious characteristics, as well as being inherently bacterial resistant due to the exceptionally high water content at the surface.
  
  
• HydroThane™ hydrophilic polyurethane resins are thermoplastic hydrogels, which can be extruded or molded by conventional means. Traditional hydrogels, on the other hand, are thermosetting in nature, often making them difficult to fabricate, assemble, and sterilize. In addition, HydroThane™ pellets are elastomeric even when dehydrated, thus requiring no special storage conditions.

Melt Processing
HydroThane™ thermoplastic hydrogels can be processed on conventional extrusion or injection molding equipment. As with all polyurethanes, certain precautions must be taken to ensure trouble free operations. The most common problems are due to excessive pellet moisture.

HydroThane™ pellets should be dried to a moisture content equal to or less than 0.01% by weight prior to melt processing. Since HydroThane™ hydrogel pellets are highly hygroscopic (they attract and hold chemisorbed water), the pellets must be dried before extrusion. Unless pellets are properly dried, HydroThane™ tubing will exhibit haze and gels and, under extreme moisture conditions, will appear "foamy."

We recommend a machine-mounted desiccant-type hopper drier, capable of reaching and maintaining a dew point of minus 5°C. Typically, the pellets must be dried for at least three hours with a drier inlet air temperature of 85°C.

Temperatures above 85°C will likely cause pellet bridging due to surface blocking. If the pellets can be predried for extended periods, such as overnight, an inlet temperature of 80°C is generally sufficient.

Physical Properties

HydroThane™ 25-93A pellets were dissolved in Dimethyl Acetamide (DMAC) solvent to produce a 25% solids solution. Several films were cast for physical testing at three moisture levels. "Normal" tensile bones were stored in the open. "Very dry" tensile bones were placed in a desiccator with PVP absorbent, and conditioned at 52°C for 24 hours prior to testing. "Wet" tensile bones were stored in distilled water at 23°C for 24 hours prior to the tests.

Extruder Conditions
Typical nominal conditions for a 1" screw in the manufacture of 7 french tubing is as follows:

FDA Status
The use of HydroThane™ in medical devices is not covered by any specific FDA regulation. It is the responsibility of the user to establish safety with the FDA through submission of an individual application. We submitted an MAF to the FDA and will approve FDA access as required in processing a customer's application. The MAF contains proprietary information on the base polymers, the manufacturing process, product release specifications, and other relevant data to assist FDA personnel in the approval process.

Technical Service
We stand ready to assist you with processing, product availability, or pricing.

This information has been gathered from standard reference sources and is believed to be accurate and reliable. CardioTech makes no other warranty, express or implied, that the results obtained from the use of this product or information contained herein shall be merchantable or fit for any particular purpose, or that the use of this product will not infringe any patent. It is offered solely for your consideration, investigation, and verification.
[In pdf format]