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Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, and has numerous applications because it is chemically inert. [3] The commonly known brand name of PTFE-based composition is Teflon by Chemours , [ 4 ] a spin-off from DuPont , which originally invented the compound in 1938. [ 4 ]
A convenient, safe method for generating TFE is the pyrolysis of the sodium salt of pentafluoropropionic acid: [6]. C 2 F 5 CO 2 Na → C 2 F 4 + CO 2 + NaF. The depolymerization reaction – vacuum pyrolysis of PTFE at 650–700 °C (1,200–1,290 °F) in a quartz vessel – is a traditional laboratory synthesis of TFE.
The molar mass of atoms of an element is given by the relative atomic mass of the element multiplied by the molar mass constant, M u ≈ 1.000 000 × 10 −3 kg/mol ≈ 1 g/mol. For normal samples from Earth with typical isotope composition, the atomic weight can be approximated by the standard atomic weight [ 2 ] or the conventional atomic weight.
The molar mass is defined as the mass of a given substance divided by the amount of the substance, and is expressed in grams per mol (g/mol). That makes the molar mass an average of many particles or molecules (potentially containing different isotopes ), and the molecular mass the mass of one specific particle or molecule.
[1] PCTFE has one of the highest limiting oxygen index (LOI). [16] It has good chemical resistance. It also exhibits properties like zero moisture absorption and non wetting. [15] [17] It does not absorb visible light. When subjected to high-energy radiation, it undergoes degradation like PTFE. [18] It can be used as a transparent film. [14]
The EW is the number of grams of dry Nafion per mole of sulfonic acid groups when the material is in the acid form. [4] Nafion membranes are commonly categorized in terms of their EW and thickness. [2] [5] For example, Nafion 117 indicates an extrusion-cast membrane with 1100 g/mol EW and 0.007 inches (7 thou) in thickness. [5]
In dissecting the cylinder, he found a mass of white solid in a quantity similar to that of the tetrafluoroethylene gas. It was determined that this material was a new-to-the-world polymer . Tests showed the substance was resistant to corrosion from most acids, bases and solvents and had better high temperature stability than any other plastic.
It has a short half-life, 0.5 and 20 ms, in solution and in the gas phase, respectively. [1] Although highly reactive, difluorocarbene is an intermediate in the production of tetrafluoroethylene , which is produced on an industrial scale as the precursor to Teflon ( PTFE ).