Materials, oxygen-free

It is claimed that the cured materials may be used continuously in air up to 300°C and in oxygen-free environments to 400°C. The materials are of interest as heat- and corrosion-resistant coatings, for example in geothermal wells, high-temperature sodium and lithium batteries and high-temperature polymer- and metal-processing equipment. 

BHA is an antioxidant. It reacts with oxygen free radicals. It can thus slow down the rate at which ingredients in a product oxidize in direct contact with air, a process that can cause changes in the taste or color. BHA can be added to the food itself, or to the packaging material, and it is used primarily to prevent fats from becoming rancid. 

Synthetic polymers are best known for their insulating dielectric properties which have been exploited for numerous applications in both the electrical and electronic industries. It was found recently that some polymers can also be rendered conductive by an appropriate treatment, thus opening the way to a new field of applications of these materials (2, 3). Usually, electrical conductivity is obtained by doping a neutral polymer, rich in unsaturation, with donor or acceptor molecules. These polymers are rather difficult to synthesize, which makes them very expensive besides they are often sensitive to environmental agents, like oxygen or humidity, thus restricting their practical use to oxygen-free systems. 

When the fluorine used for synthesis contained traces of oxygen, the solid behaved as a powerful oxidant (causing 2-propanol to ignite on contact) and it also exploded on impact. Material prepared from oxygen-free fluorine did not show these properties, which were ascribed to the presence of traces of dioxy geny 1 tetrafluoroborate (above). 

For other organic materials used in low temperature slush-baths with liquid nitrogen see R.E.Rondeau [J.Chem.Eng.Data 11 124 7966]. NOTE that the liquid nitrogen should be oxygen-free. Liquid nitrogen that has been in contact with air will contain oxygen (see Table 8 for boiling points) and should not be used. 

The various kinds of pitch used here were carbonized in a porcelain boat within a heated horizontal cylindrical retort. The temperature of the sample, which was measured by means of a thermocouple placed just above the boat, could be maintained constant to within 1°C. All carbonization runs were carried out with an atmosphere of oxygen-free nitrogen. The heated material was cooled to room temperature before examination. 

---