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Non‐markovian effects in NMR relaxation processes: An application to molecular dynamics in branched and cross‐linked solid polymers
Author(s) -
Denner Paul,
Götz Horst,
Eichhorn Falk
Publication year - 1991
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19910520126
Subject(s) - polybutadiene , polymer , molecular dynamics , relaxation (psychology) , dynamics (music) , chemical physics , natural rubber , materials science , fractal , polymer chemistry , polymer science , copolymer , statistical physics , chemistry , computational chemistry , physics , mathematics , composite material , mathematical analysis , psychology , social psychology , acoustics
The dynamic of restricted rotatranslation of mobile structural defects along a polymer chain are treated with an equation of motion with a non‐Markovian, stochastic force. The MORI/KUBO/ZWANZIG representation gives a stochastic process with a memory where the loss of correlation is dependend on the restriction of diffusional motion of defects. The influence of crosslinks and branchings of the polymer chains on the molecular dynamics are discussed. The analytical spectral densities of ω −‐α ‐type characterized by the fractal dimensions of the relevant processes in the different polymeric systems, e. g. cis‐polybutadiene, cis‐polyisoprene, styrene‐butadiene‐rubber, high density and linear low density polyethylenes, are compared with the observed NMR data.