Fluoropolymer Blog

ARTIFICAL HEART VALVE

noreply@blogger.com (fluoropolymer_blogger) — Thu, 14 Feb 2008 16:22:00 +0000

Artificial heart valve

Heart valves are flaps of tissue within the heart. They open and close to allow blood to flow into the correct cardiac areas in the right direction. Blood is supposed to flow from one of the heart's four chambers to the next. Closing a valve prevents any blood from leaking back. When one of the heart's four valves becomes too diseased or damaged to function properly, blood does not reach the proper area in the right volume. The only effective treatment is valve replacement. Valve replacement was not possible until the advent of open-heart surgery in the 1950s. Researchers set out to design a valve that could be easily implanted, have a low rejection rate, would not promote clot formation, and enjoy long-term durability.

American surgeon Charles A. Hufuagel (1916-) inserted a tube-and-float device into a patient's descending aorta in 1952 to prevent aortic backflow. In 1960 Dwight Harken implanted an artificial cardiac aortic valve into a patient. Nina Braunwald replaced a mitral valve with an artificial one shortly after that.

The first completely successful artificial heart valve was designed and implanted in a human patient by surgeons Albert Starr (1926-) and M. L. Edwards in Portland, Oregon in 1961. Their device, the Starr-Edwards valve, is now a standard in the field. The valve is made of a combination of materials and includes a hollow metal ball, an alloy (metal composite) cage, and a Teflon base. Heart valve designers and manufacturers later took advantage of new technologies developed for the space program and included materials like Pyrolite carbon, a strong and durable new substance, in artificial heart valve designs.

There is always the danger of blood clot formation after a valve is implanted. Because of this, patients are required take anticoagulation medication for life. An alternative is to use a porcine (pig) aortic valve, which carries a much lower risk of clot formation. Using this valve does not require anticoagulation medication, but porcine valves do not last as long as mechanical heart valves.

Taken from Discoveries In Medicine

Fluoropolymers Help Protect

noreply@blogger.com (fluoropolymer_blogger) — Wed, 02 Jan 2008 13:52:00 +0000

Products made from fluoropolymers are indispensable to modern life. How? By saving lives, preventing injury & disease. Through the advancement of communications technologies they keep our world connected.

FIREFIGHTERS - Fluoropolymers are used in the manufacturing of durable fire-retardant fabrics that help shed water, resist abrasion and retain insulation, which diminishes the chance for burns.

AIRCRAFT CREW AND PASSENGERS - Aircraft fire is significantly reduced by using fluoropolymer based composites for wiring insulation.

PROTECTING FACTORY WORKERS - Workers are protected from corrosive, alkaline or acidic chemicals by wearing protective garments made of nylon or polyester coated with chemically resistant polymers such as PTFE (polytetrafluonocthvlene) a type of fluoropolymers.

OFFICE WORKERS - Using fluoropolymers to insulate wire and cable placed in the air space between a suspended ceiling and the structural floor above reduces the risk of fire in office buildings.

Flame resistant fluoropolymers do not interfere with signal transmission and are good insulators of low-voltage electricity, which includes, data-transmission materials, such as phone cables, computer wires and cables, coaxial cable and hookup wire.

Nervious About Nonstick?

noreply@blogger.com (fluoropolymer_blogger) — Mon, 17 Dec 2007 19:21:00 +0000

Nervous About Nonstick?

Easy to clean and incredibly popular, this cookware is still considered potentially toxic by some experts. Good Housekeeping settles the debate — and tells you how to use it safely.

By Amanda Schaffer

Photo by: Lara Robby

How much do women love nonstick? The sales figures tell the story: In 2006, pots and pans with this special coating (Teflon is the best-known version) constituted 90 percent of all aluminum cookware sold, according to industry numbers. Yet despite nonstick’s advantages (its surface makes cleanup easy and also allows cooks to use less oil and butter), it has come under fire in recent years over concerns about toxic chemical emissions. Dozens of reports and studies — from both industry and outside sources — have turned up conflicting conclusions. So we talked to numerous experts, looked at the major studies — and also conducted our own lab tests at the Good Housekeeping Research Institute — to find out: Just how safe are nonstick pots and pans?

Sticking Point

How fast will a nonstick pan reach 500°F, the point at which its coating can start to decompose? The Good Housekeeping Research Institute put three pieces of nonstick cookware to the test: a cheap, lightweight pan (weighing just 1 lb., 3 oz.); a midweight pan (2 lbs., 1 oz.); and a high-end, heavier pan (2 lbs., 9 oz.). We cooked five dishes at different temperatures on a burner that's typical in most homes. The results: Even we were surprised by how quickly some of the pans got way too hot.

At very high temperatures — 660° F and above — pans may more significantly decompose, emitting fumes strong enough to cause polymer-fume fever, a temporary flu-like condition marked by chills, headache, and fever. (The fumes won’t kill you — but they can kill pet birds, whose respiratory systems are more fragile.) At 680° F, Teflon releases at least six toxic gases, including two carcinogens, according to a study by the Environmental Working Group, a nonprofit watchdog organization. “However, even if those gases are formed, the odds that you’re going to breathe enough of them to be sick are low,” says Wolke, a point corroborated by several of the experts we interviewed. What no one has yet researched is whether overheating these pans regularly for a prolonged period might have long-term effects.

Outdated Fears

If cookware is flaking, you might accidentally swallow a chip — but don’t be concerned, says Paul Honigfort, Ph.D., a consumer safety officer with the Food and Drug Administration. “A small particle would most likely just pass through the body, without being absorbed and without having any ill effect on the person’s health,” he says.

Also of less concern than previously believed: the danger of nonstick pans exposing the family to PFOA (perfluorooctanoic acid). A chemical used to manufacture the fluoropolymers that make up nonstick cookware’s coating, PFOA is associated with tumors and developmental problems in animals, and experts are concerned about its possible effects on humans. In 2004, DuPont agreed to pay up to $343 million to settle a lawsuit alleging that PFOA, used in the manufacture of Teflon at a certain plant, had contaminated drinking water nearby. This year, a study at Johns Hopkins Bloomberg School of Public Health found an association between PFOA exposure and small decreases in head circumference and body weight in infants (except those born by cesarean section). Last year, an independent review panel advised the EPA to classify PFOA a “likely ” human carcinogen. The EPA has not yet adopted the recommendation, which is disputed by DuPont. In the meantime, the EPA has reached an agreement with eight companies, including DuPont, to phase out the use of PFOA completely by 2015.

But while PFOA is still a concern, it’s unlikely that we get most of our exposure from the use of nonstick pans. Sources of PFOA are everywhere: in microwave-popcorn bags, fast-food packaging, shampoo, carpeting, and clothing. Studies show that most of us have PFOA in our bloodstreams, and babies show trace amounts at birth. The FDA has tested nonstick pans to evaluate the danger of PFOA exposure to humans. “What we found was that the manufacturing process used to make those pans drives off the PFOA,” says Honigfort, meaning that the chemical evaporates. “The risk to consumers is considered negligible.”

Cook-Smart Precautions

You can use nonstick safely, as long as you use it properly. Any food that cooks quickly on low or medium heat and coats most of the pan’s surface (which brings down the pan’s temperature) is unlikely to cause problems; that includes foods like scrambled eggs, pancakes, or warmed-up leftovers. And many other kinds of cooking are safe as well: In GHRI’s tests, the only food prep that yielded a nonstick pan temperature exceeding 600ºF in less than 10 minutes was steak in a lightweight pan. But to be cautious, keep these tips in mind.

Never preheat an empty pan. In GHRI’s tests, each of the three empty nonstick pans we heated on high reached temperatures above 500 degrees in less than five minutes — and the cheapest, most lightweight pan got there in under two minutes. Even pans with oil in them can be problematic; our cheapest pan zoomed to more than 500 degrees in two and a half minutes.
Don’t cook on high heat. Most nonstick manufacturers, including DuPont, now advise consumers not to go above medium. (DuPont maintains, however, that Teflon does not pose any health risks, and that its guideline is simply meant to maximize the life of the product.)
Do people still cook on high, despite manufacturers’ instructions? “There’s no statistical answer to that question,” says the FDA’s Honigfort. But you know if you’re doing it, and if you are, the consensus is clear: It would be safer if you stopped. (Since some people won’t switch to medium, or will overheat accidentally if distracted, says Jane Houlihan, vice president for research at the Environmental Working Group, “we recommend that people simply phase out the use of nonstick pans.”) To play it safe, set your knob to medium or low and don’t place your nonstick cookware over so-called power burners (anything above 12,000 BTUs on a gas stove or 2,400 watts on an electric range); those burners, seen more often in recent years, are intended for tasks like boiling a large pot of water quickly.
Ventilate your kitchen. When cooking, turn on the exhaust fan to help clear away any fumes.
Don’t broil or sear meats. Those techniques require temperatures above what nonstick can usually handle.
Choose a heavier nonstick pan. Lightweight pans generally heat up fastest, so invest in heavier-weight cookware — it’s worth the extra money.
Avoid chipping or damaging the pan. We’ve all been told not to use metal utensils on nonstick pans. Newer products may be harder to chip, “because the adhesion between the pan and the nonstick coating is better,” says Honigfort. Still, if pans do chip or flake, they may be more likely to release toxic compounds, says Kannan of the New York State Department of Health. To prevent scratching, use wooden spoons to stir food, avoid steel wool, and don’t stack these pans. (If you do, put a paper towel liner between them.)
How long can you expect your nonstick cookware to last? DuPont’s estimate, based on moderate usage, is three to five years. Some experts, like Kannan, advise replacing your nonstick cookware every couple of years. What should you do if the pan does become damaged? A clear answer, from Kannan: Throw it out.

This article was taken from the Good Housekeeping.

Check out the Good Housekeeping Research Institute Best Picks: Nonstick Cookware and Best Picks: Traditional Cookware for different options and styles.

What is Teflon®?

noreply@blogger.com (fluoropolymer_blogger) — Thu, 13 Dec 2007 19:57:00 +0000

Teflon® is a registered trademark and a brand name owned by DuPont. Teflon® is not a chemical, but rather, represents a family of high-performance fluoropolymer based products that are used in a wide variety of industrial and consumer applications. The Teflon® brand has come to represent a variety of benefits to consumers including easy clean, nonstick, repellency and durability. Since the early 1960s, Teflon® brand non-stick coatings have been used on cookware. Although consumers may use the brand, Teflon®, as a generic term to refer to all non-stick cookware, the Teflon® brand refers only to certain non-stick coatings manufactured by DuPont and sold under the Teflon® brand name. The coating on non-stick cookware is made from a liquid "paint" which contains PTFE (polytetrafluoroethlyene) fluoropolymer and sometimes other fluoropolymers. The final cookware coating is a dried, durable non-stick material which delivers the easy clean and non-stick performance that you expect from your cookware coated with Teflon®

Teflon® has also become the common name used to refer to fluoropolymer tubing, of which there are several types, including PFA, PTFE, PVDF and FEP. In order to make this tubing, fluoropolymer resin is supplied in powdered form which is mixed, preformed, extruded into a paste, and then extruded again to form tubing. PTFE is the most flexible of all fluoropolymers offered. It has the broadest temperature range of any fluoropolymer and can resist highly corrosive liquids and gases even at elevated temperatures. The smooth surface finish and lowest coefficient of friction & lubricity make it ideal for bushing or bearing applications. PTFE’s translucent white color will vary naturally from lot to lot, however the quality and physical properties do not change.