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SUMMARY:A study of the entanglement in polymer melts - Panagiotou \, E (Na
 tional Technical University\, Athens)
DTSTART:20121113T113000Z
DTEND:20121113T123000Z
UID:TALK41484@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Polymer melts are dense systems of macromolecules. In such den
 se systems the conformational freedom and motion of a chain is significant
 ly affected by entanglement with other chains which generates obstacles of
  topological origin to its movement. In this talk we will discuss methods 
 by which one may quantify and extract entanglement information from a poly
 mer melt configuration using tools from knot theory. A classical measure o
 f entanglement is the Gauss linking integral which is an integer topologic
 al invariant in the case of pairs of disjoint oriented closed chains in 3-
 space. For pairs of open chains\, we will see that the Gauss linking integ
 ral can be applied to calculate an average linking number. In order to mea
 sure the entanglement between two oriented closed or open chains in a syst
 em with three-dimensional periodic boundary conditions (PBC) we use the Ga
 uss linking number to define the periodic linking number. Using this measu
 re of linking to assess the extend of entanglement in a polymer melt we st
 udy the effect of CReTA (Contour Reduction Topological Analysis) algorithm
  on the entanglement of polyethylene chains. Our results show that the new
  linking measure is consistent for the original and reduced systems. \n\nF
 or a collection of open or closed chains in 3-space or in PBC\, we define 
 the linking matrix. The eigenvalues of this matrix provide insight into th
 e character of the entanglement.\n\n
LOCATION:Seminar Room 1\, Newton Institute
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