Clear, strong plastic comes around

Summit, NJ —What can you do with a lightweight thermoplastic that offers clarity, strength, stiffness, chemical resistance, and good electrical properties? Judging from the emerging applications for cyclic olefin copolymers (COCs), the answer is plenty.

COCs have been floating around in labs and small batches for years, but they will become more readily available in commercial quantities starting next month when Ticona launches the first full-scale production plant for its Topas COC line. Packaging applications, which benefit from the barrier properties and strength of cyclic olefins, will doubtless eat up a healthy portion of the new capacity. Yet a favorable balance of optical, electrical, and mechanical properties (see table) also makes COCs a good fit for variety of engineered components, according to Donal McNally, who manages Topas in North America. "Not many plastics combine clarity with such a high specific stiffness," he notes.

Here's a look at some of the most promising engineering applications for cyclic olefin copolymers:

See clearly. Given its clarity, perhaps the most obvious fit for Topas has been in optical parts, and McNally does cite a variety of high-precision lens applications—for projection TVs, lasers, LEDs, and even tiny ones for fiber optics. But optical properties aren't the only thing driving cyclic olefins into these applications. McNally adds that low water absorption contributes to environmentally stable optical components. Another up-and-coming application uses Topas for a light guide within an electro-optic connector—in which the material successfully withstands temperatures above its glass transition point for short period of time.

Breaking the glass barrier. Topas is seeing some use as a replacement for glass in analytical and diagnostic systems. McNally reports that Topas has already replaced everything from simple vials to precision plates formerly made from costly ground glass. The properties driving these lab uses include chemical resistance (to solvents, acids, and alkalis), high UV trans- mission, high moisture barrier, and optical clarity, McNally says.

A shocking film. When used for capacitance films, Topas can be metallized on both sides simultaneously—not just one as with polypropylene. McNally says this capability lets smaller areas of film handle more energy. What's more, Topas makes for an efficient capacitor, given its combination of a relatively low dielectric loss and relatively high dielectric constant. McNally sums up the result of these two factors as "More capacitance in less space."

There's more. Other applications keep popping up all the time. McNally recently fielded inquiries about Topas foams for an aerospace insulation that needs the material's electrical properties; for clear ion-exchanger pipes that require chemical resistance; and for low-load gears that call for strength and creep resistance. "We're discovering new uses for the materials nearly every day," McNally says.