Wednesday, November 09, 2005

Products Like Teflon: Chlorofluorocarbons

In the previous post, CFCs were mentioned as the chemicals that had similar negative impacts on the ozone layer as carbon tetraflourides. Nevertheless, it had not been fully explained how CFCs behave. Besides, as aforementioned, having a relatively long life span of 20-100 years, CFCs are similar to Teflon in that it was a chemical that was produced during the 1930's that was almost ubiquitously used, without tangible replacements.
CFCs, to be exact, were first developed in the late 20s and early 30s as alternatives to the dangerous substances used then used as coolants in refrigeration systems and air conditioners. However, after decades of application, it had finally been determined in 1984 that CFCs had a direct impact on the depletion of the ozone layer. Even now, due to their chemical properties that allow them to react with ozone hundreds of times before finally being scavenged by other chemicals, CFCs continue to damage the ozone layer. To prevent the ubiquitous usage of a substance of a potential threat to the ozone layer, the replacements to CFCs are now required to be tested for ozone depletion potential. Whatever the case may be with the replacements or the remnants of CFCs in their threat to the ozone, it is unfortunate that, much like the Teflon-like PFOS, CFCs were not fully tested—or their harmful properties not realized—for their ultimate damages. The unfortunate fact that these products were not fully tested, as well as the fact that there were no viable replacements for these widely used substances, has now led to the progeny of the people who developed those substances to eliminate those substances’ waste-like and eventually inimical remnants. If Teflon were to be found to behave in ways that could be a threat, as do CFCs and PFOS, it should be phased out as soon as possible so that we do not leave our children with the burden of having to clean up the threats of the persistent Teflon.

Tuesday, November 08, 2005

Carbon Tetraflouride and its Interactions with Ozone

Carbon tetrafluoride is a byproduct of overheating Teflon beyond a temperature of 1202 degrees Fahrenheit. The substance has a molecular weight of 88 grams per mol. Carbon tetrafluoride is a stable, non-flammable, colorless gas.

Carbon tetraflouride interacts with the ozone layer in a similar fashion with a CFC. The process of ozone depletion starts by carbon tetrafluoride floating up into the ozone layer. When it arrives, the molecule is struck by UV light, seperating a fluorine atom from the carbon tetrafluoride. This fluorine atom collides with an ozone atom in the ozone layer, making a molecule of oxygen and fluorine monoxide.

When a singlet oxygen atom collides with fluorine monoxide, the oxygen replaces the fluorine atom to create a molecule of oxygen and a lone fluorine atom. This starts the process again, causing the deterioration of the ozone layer by turning it into oxygen. Measures have been taken to reduce the amount of CFC emission, but since CFCs have a life span of 20-100 years, previously emitted CFCs will do damage for years to come.

Teflon and Car Engines

Cars and trucks all experience a great amount of wear and tear on their parts. However, the most damage appears when an engine cold-starts. This is due to the lack of oil flowing through the engine at the time, which forces the engine parts to work under more friction, and therefore causing more wear and tear.

A new brand of oil called Techrobond is being researched into and may be the solution of the cold-start problem, using a catalyst. The catalyst temporarily bonds with the Teflon, then attaches it to the metal surface. Once the Teflon-metal bond is made, the catalyst detaches and moves on to form another temporary bond with more Teflon, then helps fuse the Teflon with another bit of metal. This bond between metal and teflon is presumed to be permanent, and the outer teflon coating reduces the amount of friction between the metal parts, therefore protecting the metal parts. Even if the nanoscopic coating cannot be seen, it is still enough to reduce the friction and when it eventually wears off, the catalyst acts to bind exposed metal pieces with teflon. This improves the life of the engine and cuts costs of maintaining it.

The Price of Teflon

Teflon is used for many different purposes, and the price range is huge. Here are some examples of the price of teflon (the prices are the lowest being sold by a commercial retailer):

A .125 x 12 x 12 sheet of regular Teflon: $29.26
A 16 oz bottle of Teflon Car Wash from Dupont: $5.99
A 9.5 inch, Teflon-coated Stir Fry Pan: $19.99
A 22 inch windshield wiper blade coated with Teflon: $14.99

A hair curler with 3/4 inch barrel, coated with Teflon: $8.99

A 32 oz bottle of Teflon wheel cleaner: $7.99
A Teflon-coated Apron: $7.98
A Teflon-Coated "Franz Bittner Loden Crush Hat (For Men)": $34.95

These are some of the general uses of Teflon. Many people use these products, or products similar to these. Some make sense, such as the Teflon-coated Apron. Others, like the Teflon-coated hair curler, seem as though they are a waste of both and Teflon. Either way, this provides a rough idea of what the prices of Teflon proudcts are today.

Friday, November 04, 2005

Applying Nonstick Coating without the Heat

Yet, another alternative to Teflon is the water-soluble, soap-like nonstick chemical developed by Donald Schmidt. According to an article from New Science Archive, this material, because of its soap-like quality in having both reactive ionic and fluoroalkyl groups, is water soluble. Moreover, once this water-soluble substance attaches itself to the surface, a second substance could be used to the now-dried first to create a nonstick surface. Unlike Teflon or other PFC’s, this material does not require excessive heat to create a nonstick coating. In addition, when applied to car bumpers, this material effectively “shed insects, soil and road tar dramatically better than conventional automobile paints”. Although Teflon cookware could very rarely pose direct threat to human health, if one is concerned about the imminent dangers of cooking Teflon-coated cookware around 464 to 1202 degrees Fahrenheit on a regular basis, this material developed by Dr. Schmidt could be an alternative, since unlike Teflon, this material needs no heat to be applied and thus does not pose threats when heated to high temperatures.

Thursday, November 03, 2005

Temperatures and Chemicals

Cookware with non-stick coatings such as Teflon have been known to relase chemicals into the air at high temperatures. This statement, however, is very vague. According to one website, many different chemicals can be released into the air at various temperatures.

At 464 degress fahrenheit, small particulate matter is dispersed. These toxic particles can cause symptoms within ten minutes of achieving this temperature.

At 680 degress fahrenheit, several chemicals are exposed. Tetrafluoroethylene, hexafluoroproprene, trifluoroacetic acid, difluoroacetic acid, monofluoroacetic acid, and perfluorooctanoic acid are formed. These chemicals are harmful to many of the body's organs, as well as the environment.

At 878 degrees fahrenheit, silicon tetrafluoride is released. It is highly toxic and mainly affects the lungs.

At 887 degrees, perfluoroisobutene is formed and can cause respiratory problems.

At 932 degrees, carbonyl fluoride and hydrogen fluoride are formed and can seriously damage the respiratory system, as well as any other cells in contact with the chemical.

At 1112 degrees, octafluorocyclobutane is formed. This chemical can cause heart problems. Additionally, perfluorobutane is formed. This chemical has over 8000 times the global warming potential as carbon dioxide.

Lastly, at 1202 degrees fahrenheit, carbon tetrafluoride is released. This chemical has 6000 times the global warming potential as carbon dioxide and can remain in the environment for over 50000 years.

There is one catch, however. When was the last time you cooked something over 464 degrees fahrenheit, let alone 1202 degrees? This just goes to show that some people exaggerate the possible effects of non-stick cookware.

Alternatives to Teflon

For those who are worried about the effects of teflon when heated to extremely high temperatures, which would most likely leave the food inedible, there are several alternatives of non-stick surfaces other than teflon.

Stainless steel is claimed to be better pan material than teflon and other non-stick chemicals. It is also said to be able to brown foods better, mainly due to the direct touching of the food and the metal surface, which a teflon-coated pan cannot give. In Cooks Illustrated, in their 2001 review of saute pans, it chose a stainless steel pan over an otherwise identical non-stick pan models.

Another alternative to teflon would be cast-iron pans. Lodge, America’s oldest family-owned cookware manufacturer, claims that they have a natural non-stick surface. However, this non-stick surface is gained through multiple "seasonings", where a thin layer of oil is added to the cast-iron pan and allowed to seep into the pan. Over time, the pan gets less sticky as more seasoning are applied overtime, giving the pan a sleek black look. However, these pans actually require oil in order for it to be non-stick, therefore adding to the fat content of the food. Another point to make is that the pan must have this non-stick coating applied over again, when with teflon, there is no need for reapplication.

Cast-iron pans and stainless steel pans are two of the more known alternatives to use instead of teflon-coated pans.

Friday, October 28, 2005

EPA and Its Close-up Study of Perfluorooctanoic Acid (PFOA)

3M's elimination of Scotchguard Protector, one of its most popular products at the time, came primarily because of the Environmental Protection Agency(EPA)'s concerns about the persistence, bioaccumulation, and toxicity of PFOS, the major ingredient in Scotchguard Protector. Because of the assumed dangers of PFOS that are associated with this elimination, which occurred in 2002, concerns were raised about a similar substance, PFOA, which primarily makes up Teflon. According to the Status of EPA Negotiations with Industry on PFOA Related Activities, EPA has been negotiating with several major companies, such as 3M or Dupont, to identify the major effects of PFOA on several laboratory animals. Similar to those of PFOS, data on the effects of PFOA on humans have not been studied insofar as to say that Teflon, or any other type of product that uses PFOA for that matter, will prove harmful in humans. However, as the dates (such as the date on the Incineration ECA, which was signed on July 8, 2005) on the Status table indicate, EPA’s such efforts to prove—or disprove—that PFOA can in fact be detrimental in humans have been recent and ongoing. In addition, EPA also offers the basic backgrounds of PFOA and the like substances in order to raise concerns about their dangers. Because Teflon and other forms of PFOA-like substances are so abundant in all kinds of forms around humans (as the previous posts indicate their applications in detail), it is a relief to see that there are organizations working to study their effects on humans, ready to eliminate such materials from the market once they are proven harmful.

Random Cool Uses of Teflon

Teflon has many other purposes besides cookware, some of which were listed in a previous blog. However, teflon is and has been used in a variety of applications that most people wouldn't think of.

One of these interesting uses of teflon came about during the Manhattan Project. This, as most people know, was a project that's purpose was nuclear weaponry. Uranium hexafluoride was used during the Manhattan Project, and it's production involved highly corrosive materials. The team agreed on using none other than Teflon! In fact, Dupont agreed to reserve all of it's Teflon for this use.

Another interesting use of Teflon is in armor-piercing bullets. Teflon is used as a coating on these bullets to reduce the amount of wear on the barrel of the gun when it fires. Because they are used on armor-piercing bullets, this teflon-coated ammunition is also known as the "cop-killer" bullets.

These uses of Teflon may not come to mind immediately when thinking of Teflon, but they sure are conveient. Perhaps the future will hold more interesting uses of Teflon.

Thursday, October 27, 2005

The Chemical Properties of Teflon

Polytetraflouroethene, the brand name is Teflon, is a polymer with the repeating strands of (-CF2-CF2-) in it. A molecule of PTFE can exceed over 30,000 daltons and the material has an extremely high density, because it packs together and forms tight crystalline structures. The material also has a low coefficient of friction, both static and dynamic. The coefficent of friction is equivalent to the coefficient of friction of rubbing wet ice over wet ice together. On its 59th birthday, it is still listed in the Guinness Book of World Records as the slipperiest material in the world, with the lowest coefficient of static and dynamic friction of any solid.

Due to the fluorine atoms surrounding the carbon and its tight structure, teflon is chemically inert, because almost nothing can react with the carbon and the tight bonding of C-F bonds, also on top of that, PTFE is extremely heavy, its molecular weight exceeding 30,000 Daltons and is packed tightly. Taken together (the good packing and the extra electrons) that means that the van der Waals dispersion forces will be stronger than in even high density poly(ethene). However, despite the molecule having C-F bonds, it does not exhibit any dipole-dipole forces. This is due to the fluorines being in a regular arrangement around the carbon atoms, which causes the forces to cancel out with each other. These attributes are desirable in the food and chemical industry which wish for things that do not corrode or react with anything when used. In addition, due to the high LDF, it allows it to withstand great temperatures without losing its chemical properties. It has an initial melting point of 342 +- 10 degrees Celsius and a secondary melting point of 327 +- 10 degrees Celsius. Teflon can also retain its chemical properties at cryogenic temperatures of -240 degrees Celsius.

PTFE is also hydrophobic and oleophobic, because it has an extrmely low surface energy value of 18.6 Newtons per meter squared. Therefore, these materials tend to bead up on the material, because the cohesion attraction is significantly stronger than its adhesion to teflon.

Thursday, October 20, 2005

Half-lives of PFCs

In the article posted previously on the persistency of Scotchguard (PFOS) in the environment, it was mentioned that PFOS is extremely persistent in the environment not only because of its ubiquitous usage in various materials for decades, but also because of its long four-year half-life. What does it exactly mean to have a half-life of four years, though? In the broad scope, a four-year half-life does not seem long; that is, compared to the 713 million years of half-life in uranium-235, it even seems miniscule. However, one aspect that factors into the half-life of the respective four years and eight years of half lives in PFOA and PFOS is that their half-lives in organisms are dependent on some of the organisms' secreted hormones. For example, according to a web page about PFOA, the biological half-life of PFOA in male rats is 70 times longer than female rats. This research went on to show that some hormones, like testosterone, play large factors in the biological breakdown of "perfluorochemicals" such as PFOS and PFOA. Thus, the half-life of PFOS and PFOA should not be disregarded because of their respective eight-year and four-year half-lives. Rather, because their half-lives can be dependent on numerous hormones from the body, they could be some of the most persistent chemicals the body has to break down. According to another site, PFOS's 8.67 years of average half-life in humans was determined from a data of half-lives in various test subjects, in whom the half-lives of PFOS ranged from 2.29 years to 21.3 years. Again, this wide range of half-lives show that these perflourochemicals (PFCs) depend heavily on the hormones secreted by each person. In addition fact that these PFCs could have rather lengthy half-lives (although largely dependent upon each subject's hormones), the fact that PFOA and PFOS are, quite literally, everywhere is another reason that even the assumed average of their half-lives should be taken seriously. PFOA and PFOS can now easily be found in all the parts around the world; in fact, in Central Canada, as well as in some parts of the Europe, PFCs such as PFOA can be found even in the rain according to some web sites. If PFCs are everywhere to a point where they can even be found in rainfalls, it would be reasonable to assume that, albeit at low levels, people are in some ways inhaling PFCs. As popular as PFC product like Teflon cookware are (or in the case of Scotchguard Protector, were) decades of their usage has put their abundance in the environment to a far greater level. Even if the half-lives of these PFCs are as "short" as they are claimed to be, if the intake of these materials due to their abundance would become great enough, the four-year or eight-year half-lives rates would not match the rate of intake. Thus, even if the four-year or eight-year half-lives seem short, the high rate of intake due to the increasing abundance of PFCs such as PFOA and PFOS makes their length of decay into a threat; and all that, keep in mind, comes with the assumption that the rate of biological half-lives of PFCs will hopefully be somewhat similar in different people. All in all, even if PFCs may not pose immediate danger to the health of mankind, materials that have such high persistence should be, at the least, scrutinized with a dubious eye.

Health Benefits using Teflon Products

In nutrition, there are some health benefits when using teflon pans to cook food. Normally, food is cooked with oils and fats to prevent the food from sticking to the pan. This is most prevalent when cooking eggs, where the egg bottom becomes completely stuck to the bottom of the pan. The usage of cooking with oils contributes a good amount of fat into a diet.

However, when using teflon pans, there is little need for oil to prevent food from sticking to the pan. This is due to teflon's non-stick and smooth surface, and allows food to be cooked with little to no oil. The usage of teflon pans marginalizes the amount of oil needed, and in turn, results in less fat consumption when eating.

If the teflon coating were to chip and break, a highly unlikely event, teflon will not cause any harm to the body, because it is not digested and is passed through the intestines and out as feces. Therefore, there is no need to worry about getting teflon particles into one's food. PFOA is also not in the finished teflon product, therefore consumption of teflon particles will not result in the consumption of PFOA.

Finally, heating teflon normally in the process of cooking will not release any toxic fumes or gases, according to a DuPont page. The teflon coat starts to deteriorate at 260 degrees Celsius, and it should be kept in mind that fats and oils start to ignite at 206 degrees Celsius. The coat completely deteriorates at 349 degrees Celsius, which is significantly above the smoking point of oils and fats. Therefore, there are very little health implications when using teflon to cook food, while teflon gives a significant health benefit, allowing food to be cooked with less oils and fats.

Teflon Safety

There are many people who believe that teflon is harmful, and many who think that it is completey safe. Regardless, there are guidelines for using teflon that many people do not know. If these are not followed, than dangerous fumes or harmful side effects could, in fact, result. A DuPont web page describes some of the safety procedures that you should follow when using teflon. One of these is to NEVER overheat the pan, or whatever you are using containing teflon. If it is empty, it should not be left in a hot oven or microwave. Normal teflon pans can normally safely withstand temperatures of up to 500 degress fahrenheit, or 260 celcius. Water boils at 212F, cookcies and cakes are typically at 325F, meat fries at 400F, the highest baking occurs with products such as vegetables at 450F. The only temperatures used for cooking are when broiling, and these temperatures can often exceed 550F. Above these temperatures, Teflon may become discolored or lose its non-sticking properties. Severe overheating of Teflon-coated cookware, at temperatures above 660F, can result in dangerous fumes. These fumes can induce flu-like symptoms in humans, but they are easily reversible. Birds, however, can die of these fumes because of their delicate respiratory systems. The symptoms, including eye, nose, throat, and respiratory irritation, are completely reversible to humans. For these reasons, do not overheat your teflon cookware. Otherwise, Teflon is completey safe.