teflon

obtained from http://www.net-master.net/~ptfedave Teflon (Polytetrafluoroethylene) How was Teflon discovered?
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In the 1960's, Dr. Roy Plunkett, a Dupont chemist, was working on a project to find alternate materials for cooling purposes. He had stored some tetrafluorethylene gas (similar to freon) in a container and left it overnite. When he returned in the morning, the gas was gone and in its place was a white wax-like substance. Teflon had been discovered.
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Properties of Teflon
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PTFE is an extaordinary material. Some say that it is the most useful material known to man. This is because it has a combination of properties that are very hard to find. Its four great properties are: 1. very low coefficient of friction, 2. highly inert, 3. high melting point, 4. wonderful electrical properties. These properties are due to its unique molecular structure.

image obtained from http://www.psrc.ums.edu/macrog/ptfe.html As you can see, PTFE is composed of carbon and fluorine. Carbon-fluorine and carbon-carbon bonds are among the strongest in single bond organic chemistry. This accounts for many of its properties. Because of the strong bonds, much thermal energy must be used to break down the material. It is also nonpolar; this leads to its chemical inertness, as the diagram demonstrates, and the fact that its electrical resistance is over 10¹⁸ . The low coefficient of friction of Teflon results from low interfacial forces between its surface and another material and the comparatively low force to deform. A good table of PTFE's properties follows.

obtained fromhttp://www.efni.com/~paradox/feflon/uses.html

Property	DIN or ASTM DIN or Standard	Unit	Value
General
Density	53479	g/cm³	2,14 - 2,19
upper continuous operating temperature without stress		° C	250 - 260
Combustibility			non-combustible
Water absorption	53495	%	< 0,01
Mechanical
Tear strength at 23° C	53456	N/mm²	29 - 39
Tear strength at 150° C			14 - 20
Yield point at 23° C	53455	N/mm²	10
elongation at break at 23° C	53455	%	200 - 500
Modulos of elasticity in tension at 23° C	53457	N/mm²	400 - 800
Maximum bending stress at 23° C	53452	N/mm²	18 - 20
Modulos of elasticity in bending	53457	N/mm²	600 - 800
Ball indentation hardness 132 / 60	53456	N/mm²	25 - 30
Shore-D hardness	53506		55 - 72
Coefficient of friction, dyn. against steel dry	*		0,05 - 02
Thermal
Melt temperature	ASTM 2116	° C	327
Deflection temperature heat deflection temp. A (18,5) kp/cm² heat deflection temp. E (4,6) kp/cm²	53461 ISO R 75	° C	50 - 60
	53461 ISO R 75	° C	130 - 140
coeffizient of linear expansion		I/K 1,00 E-5	10 - 16
Thermal conductivity at 23° C	52612	W/K · m	0,23
specific heat at 23° C		KJ/Kg · K	1,01
Oxygen index			>95
Electrical
Dielectric constant at 10³ Dielectric constant at 1,00 E6	53483		2,0 - 2,1
Dielectric constant at 10³ Dielectric constant at 1,00 E6	53483		2,0 - 2,1
Dissipation factor at 10³ Dissipation factor at 1,00 E6	53483	1,00 E-4	0,3 - 0,5
Dissipation factor at 10³ Dissipation factor at 1,00 E6	53483	1,00 E-4	0,7 - 1,0
Volume resistivity	53482	·cm	1,00 E18
Surface resistance	53482		1,00 E17
Tracking resistance	53480		KA3c
Arc resistance	ASTM 495	sec.	>360
Dielectric strength	53481	KV/mm	40 - 80

* This test is not standardised. The coefficient of friction ist influenced by several factors. The indicated value is only a rough guideline value. This table was obtained from http://www.fietz.de/ptfe_phe.htm.