December 30, 2006

THE fourth decade of the last century, to the present times, American chemical industry, successfully could introduce a number of polymers to benefit industrial activity. Neoprene and nylon served the harbinger for the revolution. The discovery of Teflon, which was surfaced on April 6, 1938 at the DuPont's Jackson Laboratory, was too an important milestone in that specific direction.

Dr Roy Plunkett, an American who discovered polytetrafluoroetheylene (PTFE), was a chemical engineer. He was born on June 26, 1910 in new Carlisle, in federal place Ohio. He did his graduation in 1932 at the Manchester College with chemistry and achieved in 1936, the doctor title at Ohio State University. Plunkett initiated his employment with DuPont de Nemours and Company in 1936, as a researcher in Jackson laboratory in Deepwater, in the Federal State of New Jersey.

Polytetrafluoroethylene (PTFE) is a fluoropolymer. People recognise it with the brand name” Teflon” as given by DuPont. PTFE is considered to have minimum coefficient of friction for any known solid material for pans and other cookware. It provides an easy option to use as a non-stick coating. PTFE, due to being non-reactive, reasoned for its popularity to use in containers and pipe work for the chemicals known as reactive. Its melting point is 327 °C, but 260 °C is the temperature at which and above, Teflon experiences deterioration in its specific characteristics.

The search of new refrigerants consequence resulted in the development of Teflon. A L Henne and Thomas Midgley, two reputable scientists and chemists, belonged to General Motors, took the specimens of two compounds to the Jackson Laboratory at Du Pont’s Chambers Works in Deepwater, New Jersey in the early 1930s. The specimens were the chemicals identified as Freon 11 and Freon 12, belonged to chlorofluorocarbons (CFCs). Which are hydrocarbons, configured by replacing some or all of the hydrogen atoms with either chlorine or fluorine atoms.

The research laboratories of the General Motors had originated those refrigerants to serve the job strictly for their refrigeration department that is known as Frigidaire. They were developed for the reason to replace in-use refrigerants as mentioned earlier. Keeping in view the developments and the achievements Du Pont had relished in the sphere of chemical engineering, Henne and Thomas Midgley, chemists of General Motors, approached to them.

This association proved a great success in producing and in promotion of a wide range of CFCs; furthermore, they met with success in putting the most promising CFCs into mass production by the mid-1930s. Retrafluorodichloroethane (CF2ClCF2Cl), or refrigerant 114, which was later on identified as 114 was proved a best seller. The success of Freon-114 prompted Kinetic to restrict all its production to benefit Frigidaire. Consequently, in late 1930s Du Pont took on the quest to explore some refrigerant, which could be developed and produced for the sake of other brands and manufacturers and the same time it could yield and serve with same effectiveness.

Roy J. Plunkett, who had been hired in 1936 after completing his doctorate at Ohio State University, was one of the chemists that were assigned for this project. Plunkett was greatly busy on a new substance belonged to CFCs; he was fancying it to serve as an effective refrigerant. This refrigerant was produced as a consequence of a reaction between tetrafluoroethylene (TFE), a gas at room conditions, and hydrochloric acid.

Plunkett and his assistant, Jack Rebok, for further research and advancements, put in order some 100 pounds of TFE and stored it up in pressure cylinders, to be hand that out as and when needed. To safeguard against any possible chances of any explosion or rupture of the cylinder, they placed the containers in dry ice.

Rebok, on the morning of April 6, 1938, coupled a cylinder of TFE with the reaction equipment, which was in the use of Plunkett and himself. According to his set plans and routine modus operandi, he was to discharge some TFE into a high temperature chamber and then spray in hydrochloric acid, but conversely at this instance, whilst he opened the valve on the TFE canister, it was observed that nothing could release from the cylinder. This occurrence invited them to examine the valve, but a cursory examination could not expose anything wrong with the valve.

This situation reasoned them to suspect a possible leakage in the cylinder. When they weighed the container, it was obvious that the most of the gas was still present inside. They contrived some attempts with valve to rectify any possible fault, but the situation continued to remain unchanged. The resultant feeling of boredom and fatigue, coupled with frustration, propelled them to remove the valve completely. They overturned the container, and gave a strong shake; some loose flecks of white powder were floated out.

The apparent situation instigated Plunkett and Rebok to cut open quite a few of the storage canisters. It was learnt that the interior walls of the cylinder were lined with a flat, waxy white coating of an unknown substance, rather than a gas. Plunkett inscribed his findings in his notebook as “A white solid material was obtained, which was supposed to be a polymerised product.”

Despite the fact that it was by and large believed that polymerisation of a chlorinated or fluorinated ethylene was not possible, and the failures in previous attempts were the reason for such believes. Probably it was some combination of temperature and pressure that had force the TFE molecules to bond together in shape of long chains, and the compound resulted turned out to include a most fascinating set of characteristics.

Plunkett remained quite a few days to examine and learn some additional properties of this substance, which rather seemed magic and fascinating. He reached to the conclusion afterwards that it was thermoplastic (Such a substance or a material that is plastic or deformable melts to a liquid state when heated, and when cooled sufficiently, freezes to form a brittle, glassy state). He observed that the substance had the quality to burn without residue.

Furthermore, he found that the substance was insoluble in cold and hot water, acetone, Freon 113, ether, petroleum ether, alcohol, pyridine, toluene ethyl acetate, nitrobenzene, isoanyl alcohol, ortho dichlorobenzene, sodium hydroxide, concentrated sulfuric acid, glacial acetic acid, and in concentrated nitric acid.

Two days later Plunkett noted some additional characteristics of the intriguing substance: “It is thermoplastic, melts at a temperature approaching red heat, and boils away. It burns without residue; the decompositive products etch glass.”

It was also learned that the substance did not char or melt, while exposed to a soldering iron or an electric arc. Humidity had no affect on that, protracted sunlight exposure failed to reason any sort of degradation in its properties. It proved unreceptive against mold and fungus.

After completion of examining and recording physical features, as a primary step Plunkett wanted to repeat the exercise that had consequence to develop that substance, the polymerised tetrafluoroethylene (PTFE). He was successful in experiments for re-creating the substance that was initially developed, accidentally in the gas cylinders. He applied for the grant of a patent on July 1, 1939; the patent rights were attained on behalf of Kinetic Chemicals, on tetrafluoroethylene polymers.