Ashaway Line & Twine Manufacturing Company - Zero Poly Information Center

Ashaway Line and Twine Manufacturing Company

What in the World is Zyex^®, Anyway?

By Steve Crandall
Vice President, Sales & Marketing
Ashaway Racket Strings

One of my pet peeves are those TV ads that tell you a product is wonderful because it "contains Hydromethoxoflam," or some such miracle ingredient, but then never tell you what "Hydromethoxoflam" is, or why it makes the product so good. Well, it should be no secret by now - at least, I certainly hope it's not a secret - that Ashaway is now producing several new Zyex^® tennis strings. And we too are making claims about how wonderful they are (which in our case are all true, of course). So, I think it's a reasonable question to ask, just what is Zyex, and why does it make such wonderful string?

Actually, Zyex is rather neat stuff, and I'll try to describe it with as little technical jargon as possible. Zyex is the trade name for a high temperature, engineering grade polymer known as polyetheretherketone, or PEEK. According to the online encyclopedia, Wikipedia, "Polyketones are a family of high-performance thermoplastic polymers. The highly polar ketone groups in the polymer backbone of these materials gives rise to a strong attraction between polymer chains, which increases the material's melting point. Such materials also tend to resist solvents and have good mechanical properties."

In layman's terms, this means that PEEK materials like Zyex have several physical properties of interest to manufacturers. Specifically, PEEK monofilaments and fibers are very tough and durable, and have excellent abrasion resistance, particularly under extreme conditions. The material's melting point is 633°F (334°C), which is very high for plastic. Its maximum continuous service temperature is 500°F (260°C), and short-term service can be up to 570°F (300°C). By contrast, PET, polyester, the material typically used for soda bottles and monofilament tennis string, loses strength rapidly as temperatures reach 200°F, and even the much vaunted aramid fibers begin to lose strength around 450°F. So PEEK is hot stuff!

In terms of abrasion resistance, PEEK also offers good performance. In tests measuring "thread on thread" abrasion conducted at room temperature, PEEK multifilaments outlasted aramid fibers by a factor of approximately 5.5. PEEK also has very low moisture uptake at 0.1%, which means you don't need to worry about a protective bag or head cover for carrying your racquets in the rain. And if perchance you want to play outside in thunder and lightning, PEEK is also a very good insulator.

In fact, one of the original applications for PEEK was as aerospace insulation designed to protect electrical wiring from abrasion damage, especially at extremes of temperature. PEEK monofil braids have also been successfully used in automotive and nuclear installation wiring. According to the Zyex website, the material can be ideal in "any enclosed situation when toxic fumes from burning wiring could pose a threat to life." I don't know if this will help with those old socks in the bottom of your gym bag, but you can't be too careful.

But perhaps the most interesting application for Zyex - other than tennis strings, of course - is in musical instrument strings. A number of manufacturers now offer Zyex violin, guitar and other musical strings. Zyex provides a subtle but appreciably fuller tone than other synthetic string materials such as nylon. It also stays in tune much longer on a guitar or violin than is possible with other conventional music strings. So when tennis players say they love the way their racquets strung with Zyex stay in tune, they have good reason.

In racquet strings, Zyex offers low dynamic stiffness that allows it to deform and recover more completely than other synthetic materials. It can also be made to have exceptionally low creep under continuous tension, allowing racquet strings to maintain tension and playability longer. And as noted previously, the manufacturer of Zyex continues to improve and "tweak" the material, making it even better for string applications. Recent advances have produced Zyex filaments that are even finer and stronger than before.

However, it takes more than Zyex to make a string. We've been working with these new filaments in our R&D lab to develop even thinner multifilament core packages with increased linear density and more cross-sectional strength. The result, we feel, is a significant advance in string technology: thinner, softer, lighter-weight strings that provide superior feel, more power, and improved ball control, while still offering the well-known Zyex playing characteristics and tension holding properties.

Our latest Zyex development is a monofilament tennis string that can actually rival natural gut in performance and outlasts it in durability. Called Zyex MonoGut in the original version, and now officially dubbed MonoGut^® ZX, this new string is designed for players seeking both gut-like playability and superior durability in a solid monofilament string, as well as players using monofilament strings in hybrid stringing patterns. Like natural gut, MonoGut ZX retains tension better than any other synthetic material and provides exceptional energy return - meaning power. Also like gut, it remains soft at higher tensions, reducing impact shock. This adds to comfort and what we call 'soft power.' MonoGut ZX contains no polyester. Its 100% Zyex monofilament construction maximizes abrasion resistance and enhances string life.

Any questions?

In racquet strings, Zyex offers low dynamic stiffness that allows it to deform and recover more completely than other synthetic materials. It can also be made to have exceptionally low creep under continuous tension, allowing racquet strings to maintain tension and playability longer. In addition to 16-, 17-, and 18-gauge multifilaments, our latest Zyex development is MonoGut^® ZX, a monofilament tennis string that can actually rival natural gut in performance and outlast it in durability.