halogens


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halogens

The elements fluorine, chlorine, bromine, iodine, astatine.
References in periodicals archive ?
Bromine, chlorine & iodine (halogens) are chemical elements which play a fundamental role in Earth's atmosphere and are implicated in a range of environmental issues.
The material is easy to process, and it contains no halogens. Furthermore, EVM elastomers can accommodate a high content of halogen-free flame retardants, such as aluminum hydroxide, and the polar rubber raw material does not swell in the presence of lubricating greases.
In this article the halogen bonding abilities of nitrobenzene along with halogens and different chlorofluorocarbons have been investigated theoretically at the B3LYP /6-31+G(d) method of DFT.
The LED's longer life means fewer replacements; fewer energy-consuming vehicles sent out on runway inspections and fewer runway repair closures." In addition, white LEDs are whiter than Halogens which tend to emit a 'yellowish' glow.
"Development of halogen-flee FR materials by RTP Company has been driven by the global push for manufacturers to eliminate halogens from their products," says Paul Killian, technical marketing manager of FR products.
Increased interest in halogen-free assemblies is a result of Non-Government Organizations (NGOs) exerting pressure on electronics manufacturers to eliminate halogens. The NGOs' primary focus is on resolving global environmental issues and concerns.
Used primarily in handheld electronics such as cell phones, PDAs, notebook/laptop computers and hard disk drives, these adhesives are formulated to contain less than 900 ppm bromine and chlorine, and 1500 ppm total halogens. Often halogen levels in these products are undetectable.
These comments ranged from a call to delete the Forward or parts of it, to recommendations to eliminate the standard altogether because there is no legislative precedent to limit halogens in electronics.
When compared to products containing halogens (such as PVC), these halogen-free cables offer considerable safety advantages.
Although lead-free PVC wire formulations are available today, many electronics companies are interested in other alternatives that are both lead-free and do not contain other halogens, such as chlorine--an integral component of PVC resin.
He adds that the LEDs are cool even while lit, so they're safer than hot-burning incandescent halogens. Gumins claims that the long-lasting LEDs will make up their cost difference within 4 years of day-and-night lighting.