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Unexpected proton spin-lattice relaxation in the solutions of polyolefin and tetrachloroethane

✍ Scribed by Yiyong He; XiaoHua Qiu; Zhe Zhou

Publisher
John Wiley and Sons
Year
2010
Tongue
English
Weight
179 KB
Volume
48
Category
Article
ISSN
0749-1581

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✦ Synopsis

Unexpected proton spin-lattice relaxation in the solutions of polyolefin and tetrachloroethane

Yiyong He, a * XiaoHua Qiu a and Zhe Zhou b '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.

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