Polytetrafluoroethylene — Teflon

Abstract

Polytetrafluoroethylene (PTFE) sounds like a lot of scientific but it is better known by its brand name: Teflon. Everyone likely have a collection of non-stick pots and pans that are coated with PTFE. The combination of chemical and physical properties of PTFE is a consequence of its true fluorocarbon structure. This unusual structure leads to a material which has an almost universal chemical inertness; complete insolubility in all known solvents below 300°C; excellent thermal stability; and unsurpassed electrical properties, including low dielectric loss, low dielectric constant and high dielectric strength. Furthermore, PTFE does not embrittle at very high or at very low temperatures.

Introduction

Almost every household has container that are Teflon coated. It is easy for us to cook in a pan and not worry about sticking but the magic coating is fascinating for us. Behind the scene, the outstanding person who found Teflon that scientific name is Polytetrafluoroethylene is Roy J. Plunkett. Plunkett has discovered that the powder proved capable of withstanding temperatures is cold about minus four hundred degrees Fahrenheit and is warm about five hundred degrees Fahrenheit. He started investigating the material. In the next 10 years of investigative research, Plunkett and the Du Pont Company introduced Teflon to the market in 1949. Since then, it has become an important coating for everything from satellite components to electric wires to cookware. [1]

Image 1: An example of almost every households has Teflon coated product.

Theory

In recent years polytetrafluoroethylene has outstanding attention such as high melting point, good resistance against chemicals and remarkably low friction. It is a new plastic being manufactured on an experimental plant scale and also insoluble in all solvents tried so far. It withstands temperatures up to 300°C for long periods without serious degradation and is not brittle at low temperatures.

Image 2: Structurally, PTFE is just like poly(ethene) except that each hydrogen in the structure is replaced by a fluorine atom.

The important thing is that PTFE has remarkable non-stick properties which is the basis for its most familiar uses in non-stick kitchen and garden tools. It also has a very low coefficient of friction and is used in things like low-friction bearings. [5]

Image 3: Polytetrafluoroethylene repeat unit. The degree of polymerization, n, is often very high (>1000).

Discussions

Fistly, the most asked question about the PPFE(Teflon) is does it cause cancer and we can easily say that it does not. According to American Cancer Society, Teflon itself is not suspected of causing cancer. [6] “The link between cancer and Teflon cookware is an completely different subject.” says Robert Wolke, professor emeritus of chemistry at the University of Pittsburgh. [7]

On the other discussion about this area is that teflon and PFOA (which is the chemical used to make teflon) are some of the most persistent chemicals all around the world and their toxic legacy will outlive every one of us. These toxins survives the next 25 generations of our offspring. Unfortunately, it is the well-known fact that it may shorten each generation’s lifespan. [8]

In addition, the other discussions about Teflon is the nuclear resonance spectra of kinds of samples of oriented and unoriented polytetrafluorethylene have been examined in the temperature range 77°K to 334°K. The changes are discussed in terms of the structure of the polymer.

Results

Polytetrafluoroethylene is a manmade polymer that has particular applications in manufactured products because of the chemical properties of PTFE. Like all organic chemicals structure determines the unique characteristics of Teflon properties and PTFE is composed of carbon and fluorine. Its properties include high molecular weight, low coefficient of friction, thermoplasticity, good dielectric properties, high electronegativity, and low chemical reactivity. The high molecular weight is a function of being polymer.

Thermoplasticity means a polymer changes properties when heated or cooled. PTFE is relatively thermoplastic because of the bonding structure and the strength of the carbon to chlorine bonds. The overall stability of the polymer orbital structure is also a cause of the thermoplasticity. To summarize that, Teflon can be melted and formed into a multitude of shapes.

PTFE, Stress vs Strain in Tension

When it comes to its bonding structure, the bonding structure of PTFE is very stable. Teflon is not very reactive to chemical agents because of the stability of the fluorine to carbon bonds.

Lastly, the unique properties of PTFE are a result of the structure of the polymer units and the strength and stability of the carbon to fluorine bonds in the polymer. [10]

PTFE, Stress vs Strain in Tension and Compression (ASTM D695)

Conclusion

PTFE has many unique properties such as very high melting point, stable at very low temperatures and these properties make it valuable in lots of applications. Excellent material for coating machine parts which focused to heat, wear, and friction.In addition, this material also used in a range of medical applications such as vascular grafts during the surgery.

References

1. Roy J. Plunkett discovers Teflon — http://www.humantouchofchemistry.com/roy-j-plunkett-discovers-teflon.htm

2. Mechanical behaviour of PTFE in tensile loading under different strain rates — http://www.sciencedirect.com/science/article/pii/S014294181100119X

3. PTFE Heat-Resistant, Chemically Inert Plastic — http://pubs.acs.org/doi/pdf/10.1021/ie50441a009

4. An unusual presentation of Teflon granuloma: case report and discussion. — http://www.ncbi.nlm.nih.gov/pubmed/19172573

5. The Polymerisation of Alkenes — http://www.chemguide.co.uk/organicprops/alkenes/polymerisation.html

6. Teflon and Perfluorooctanoic Acid (PFOA) — http://www.cancer.org/cancer/cancercauses/othercarcinogens/athome/teflon-and-perfluorooctanoic-acid--pfoa

7. Teflon Pans and Cancer: Is There a Link? — http://www.webmd.com/cancer/features/teflon-pans

8. How Toxic is Teflon ? — http://greenlivingideas.com/2012/06/13/how-toxic-is-teflon/

9. Encyclopedia, Teflon — http://www.encyclopedia.com/topic/Teflon.aspx

10. Teflon (PTFE) : PTFE Teflon Properties — http://www.polymer-search.com/teflon.html

11. Teflon PTFE Handbook — http://www.rjchase.com/ptfe_handbook.pdf

Image-1 http://web.tradekorea.com/upload_file2/sell/46/S00013246/water_based_ptfe_coating.jpg

Image-2 http://www.chemguide.co.uk/organicprops/alkenes/makeptfe.gif

Image-3 http://www.coleparmer.com/assets/techinfo/images/Zeus_Chem_Resistance_img_5.jpg