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Unexpected proton spin‐lattice relaxation in the solutions of polyolefin and tetrachloroethane
Author(s) -
He Yiyong,
Qiu XiaoHua,
Zhou Zhe
Publication year - 2010
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2617
Subject(s) - chemistry , polyolefin , polymer , proton spin crisis , deuterium , proton , solvent , relaxation (psychology) , paramagnetism , lattice (music) , spin–lattice relaxation , atmospheric temperature range , thermodynamics , condensed matter physics , organic chemistry , atomic physics , nuclear physics , psychology , social psychology , physics , layer (electronics) , acoustics
‘Unexpected’ proton spin‐lattice relaxation ( T 1 ) times are reported for the solutions of poly(ethylene‐ co ‐1‐octene) and tetrachloroethane‐ d 2 . For the residual protons of the deuterated solvent and the methyl and vinyl protons at the polymer chain ends, their T 1 relaxation times vary significantly with both the polymer concentration and molecular weight over a wide range. The T 1 s also decrease with increasing temperature at relative high temperatures. Such behaviors are in contrast to most reported polymer solutions in which the T 1 has nearly no concentration or molecular weight dependence in the dilute and semi‐dilute regime, and normal dependence on temperature. Further investigation revealed that the paramagnetic oxygen effect did shorten the measured proton T 1 s, but cannot account for the unexpected T 1 dependences. Spin rotation is proposed to provide a reasonable explanation. Copyright © 2010 John Wiley & Sons, Ltd.