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SUMMARY:New X-ray method for monitoring of polymers radiation crosslinking
DTSTART;VALUE=DATE-TIME:20160705T090000Z
DTEND;VALUE=DATE-TIME:20160705T100000Z
DTSTAMP;VALUE=DATE-TIME:20260819T045743Z
UID:indico-contribution-1256@indico.inp.nsk.su
DESCRIPTION:Speakers: Boris Tolochko (Institute of solid state chemistry a
 nd mechanochemistry)\, Marat Sharafutdinov (ISSCM SB RAS\, BINP SB RAS)\nI
 n this work the effect of radiation of relativistic electrons on the cryst
 al structure of polyethylene after radiation crosslinking studied. The mai
 n attention was paid to changes in the temperature of the Debye. The struc
 ture factor equation given earlier yields the diffracted intensities as th
 ough all atoms were stationary. As the temperature rises the atoms execute
  increased excursions from their average position. Such excursions can inv
 olve complex coupled motions of several atoms. However if one restricts co
 nsideration to just the independent motions of each atom there is a relati
 vely simple trick that can be used which is to (artificially) modify the a
 tomic scattering factors\, f\, of each atom to represent the net broadenin
 g of their electron clouds resulting from atomic motion. For example a giv
 en atom will have its "stationary" f changed to fT according to: fT = f ex
 p(−B sin2θ / λ2) where T is the temperature and B = 8π2u2 (units of A
 2 )\, u2 being the root mean square displacement of the atom from its aver
 age position. The B values are often referred to as B factors (Debye-Walle
 r is a another\, similar\, term often used) and increase with temperature 
 (typical values are 0.2 to 0.8 A2 ). So clearly temperature will modify th
 e diffraction intensities by changing the various values of f to fT in the
  structure factor equation.\nTo determine the Debye powder X-ray series wa
 s filmed at different temperatures of the polyethylene samples irradiated 
 by relativistic electrons.\nThe method allows to monitor the changes in th
 e structure upon irradiation.\n\nhttps://indico.inp.nsk.su/event/3/contrib
 utions/1256/
LOCATION:Budker INP 2nd and 3rd floors
URL:https://indico.inp.nsk.su/event/3/contributions/1256/
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