Optivak

Manufacturing
Optivak is versatile in its manufacturing capabilities and may be saw cut, milled, routed, die cut and punched.  Carbide tools are recommended for trimming and machining.  The sheet must be clamped securely and minimal cuts should be used to avoid chipping and cracking.  Good steel rule die should be used for die cutting operations.

Predrying is not normally required for thermoforming.  When the sheet has been exposed to high humidity for a long period of time and drying is needed, best results are obtained at 148 F for eight (8) hours.

The normal forming temperature range is 250-320 F with the optimal temperature being 260 F.  Due to its quick heat cycle characteristics, working time is short (1-2 minutes).  Mold temperature is critical and should be maintained at 130-140 F to allow mold accuracy replication and prevent premature or uneven cooling.  Frame heat until sagging occurs.  Preheating metal frames and clamping areas is recommended.

Optivak may be solvent welded using Methylethylketone (MEK}, Weldon #3 solvent (Industrial Chemical Service, Gardena, California), or #763X Super Vinyl Adhesive (Flexcraft Industries, Newark, New Jersey).

Sterilization
Optivak can not be heat sterilized, because of its low softening point.  It may be sterilized using either radiation with a maximum of 5.0 megarads or ethylene oxide (used in a 12%/88%: ethylen oxide/freon gas mix).

Precautions
Optivak is a combustible thermoplastic and therefore should be stored in a cool dry area.  Because the material is non-ultraviolet stabilized it is not recommended for outdoor applications. It is possible for the mold to be too smooth.  This will cause mark-off and therefore inaccurate model replicator.  If air holes are used to draw vacuum they should be small. Using 1/32'' to 1/16" diameter holes will prevent marking of the plastic.

Optivak must be thermoformed under the right conditions.  The most frequent problem is the development of bubbles of gas in the plastic.  This is caused by either too high a molding temperature or excessive moisture or both.  Dry sheets or reduce working temperature to solve this problem.

Most reagents will cause slight yellowing upon exposure.  Use light concentrations of acids to clean. Acetone will cause discoloration and swelling of surface.

Applications
Applications of this material are similar to those of optical sheet plastics, such as Surlyn.  The advantage of economy, low working temperature, fast cycle times, and high impact resistance make Optivak an excellent choice for Prosthetic Check Sockets, facial burn masks, and all shells and cuffs where visualizing underlying tissues is critical.

Sheet Chart
Optivak is a thermoplastic copolyester sheet material, featuring excellent clarity and impact strength.  Optivak thermoforms with ease, utilizing low forming temperatures and quick cycle times.  Optivak may be used in deep draw situations and mold detail reproduction is outstanding.  It has superior thermoformability, clarity, rigidity, impact resistance, and significantly lower cost than the earlier optical resins such as Surlyn.  These qualities make it the new standard in visible check sockets designed to allow visual analysis of soft tissue compression forces.  Also known as: Vivak, Durr-plex.