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Radikalreste

English translation: remaining radicals, the rest of the radicals

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GLOSSARY ENTRY (DERIVED FROM QUESTION BELOW)
German term or phrase:Radikalreste
English translation:remaining radicals, the rest of the radicals
Entered by: Goldenbead
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01:53 Nov 29, 2006
German to English translations [PRO]
Science - Chemistry; Chem Sci/Eng / macromolecular chemistry
German term or phrase: Radikalreste
instability of polyacrylamide solutions (related to this)
Goldenbead
India
Local time: 18:25
remaining radicals, the rest of the radicals
Explanation:
The first step in producing polymers by free radical polymerization is initiation. This step begins when an initiator decomposes into free radicals in the presence of monomers. The instability of carbon-carbon double bonds in the monomer makes them susceptible to reaction with the unpaired electrons in the radical. In this reaction, the active center of the radical "grabs" one of the electrons from the double bond of the monomer, leaving an unpaired electron to appear as a new active center at the end of the chain. Addition can occur at either end of the monomer. This process is illustrated in the following animation in which a chlorine atom possessing an unpaired electron (often indicated as cl-) initiates the reaction. As it collides with an ethylene molecule, it attracts one of the ethylene's pair of pi bonded electrons in forming a bond with one of the carbons. The other pi electron becomes the active center able to repeat this process with another ethylene molecule. The sigma bond between the carbons of the ethylene is not disturbed. (Note that a molecular orbital model is employed here in describing this process. See any introductory college chemistry text for further discussion)



In a typical synthesis, between 60% and 100% of the free radicals undergo an initiation reaction with a monomer. The ** remaining radicals ** may join with each other or with an impurity instead of with a monomer. "Self destruction" of free radicals is a major hindrance to the initiation reaction. By controlling the monomer to radical ratio, this problem can be reduced.
Selected response from:

Zareh Darakjian Ph.D.
United States
Local time: 05:55
Grading comment
Thanks for taking so much trouble
4 KudoZ points were awarded for this answer



Summary of answers provided
3 +1remaining radicals, the rest of the radicals
Zareh Darakjian Ph.D.


Discussion entries: 4





  

Answers


12 mins   confidence: Answerer confidence 3/5Answerer confidence 3/5 peer agreement (net): +1
remaining radicals, the rest of the radicals


Explanation:
The first step in producing polymers by free radical polymerization is initiation. This step begins when an initiator decomposes into free radicals in the presence of monomers. The instability of carbon-carbon double bonds in the monomer makes them susceptible to reaction with the unpaired electrons in the radical. In this reaction, the active center of the radical "grabs" one of the electrons from the double bond of the monomer, leaving an unpaired electron to appear as a new active center at the end of the chain. Addition can occur at either end of the monomer. This process is illustrated in the following animation in which a chlorine atom possessing an unpaired electron (often indicated as cl-) initiates the reaction. As it collides with an ethylene molecule, it attracts one of the ethylene's pair of pi bonded electrons in forming a bond with one of the carbons. The other pi electron becomes the active center able to repeat this process with another ethylene molecule. The sigma bond between the carbons of the ethylene is not disturbed. (Note that a molecular orbital model is employed here in describing this process. See any introductory college chemistry text for further discussion)



In a typical synthesis, between 60% and 100% of the free radicals undergo an initiation reaction with a monomer. The ** remaining radicals ** may join with each other or with an impurity instead of with a monomer. "Self destruction" of free radicals is a major hindrance to the initiation reaction. By controlling the monomer to radical ratio, this problem can be reduced.

Zareh Darakjian Ph.D.
United States
Local time: 05:55
Specializes in field
Native speaker of: Native in EnglishEnglish, Native in ArmenianArmenian
PRO pts in category: 162
Grading comment
Thanks for taking so much trouble

Peer comments on this answer (and responses from the answerer)
agree  aruna yallapragada
17 mins
  -> Thank you, very much Dr. Yallapragada!
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