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dc.contributor.author | Fischer E. | |
dc.contributor.author | Kimmich R. | |
dc.contributor.author | Fatkullin N. | |
dc.date.accessioned | 2018-09-17T20:21:00Z | |
dc.date.available | 2018-09-17T20:21:00Z | |
dc.date.issued | 1997 | |
dc.identifier.issn | 0021-9606 | |
dc.identifier.uri | https://dspace.kpfu.ru/xmlui/handle/net/133378 | |
dc.description.abstract | Based on theoretical considerations [N. F. Fatkullin, Sov. Phys. JETP 72, 563 (1991)], immaterial spin diffusion mediated by flip-flop transitions of dipolar coupled spins on different macromolecules was predicted to influence the diffusion coefficient measured in nuclear magnetic resonance field-gradient experiments. In order to test this hypothesis, we have carried out supercon fringe field proton magnetic resonance diffusometry experiments with polyethylene oxide melts (Mw=438 000) using field gradients of up to 60 T/m. The polymer chains were dispersed in a matrix of deuterated chains of an equivalent molecular mass. The time-dependent segment diffusion coefficients measured in the diluted and undiluted polymer coincided for diffusion times below about 200 ms. However, increasing the diffusion time up to 1 s leads to a reduction of the diffusion coefficient in the deuterated matrix by a factor of about 2 relative to the undeuterated system. The long-time diffusion coefficient measured with long polymer chains, which are subject to interchain spin couplings, is obviously strongly influenced by spin diffusion mediated by flip-flop transitions of dipolar coupled spin pairs. This holds true in spite of the relatively long flip-flop time, which is estimated to be of the order 0.1 s. © 1997 American Institute of Physics. | |
dc.relation.ispartofseries | Journal of Chemical Physics | |
dc.title | Spin diffusion in melts of entangled polymers | |
dc.type | Article | |
dc.relation.ispartofseries-issue | 23 | |
dc.relation.ispartofseries-volume | 106 | |
dc.collection | Публикации сотрудников КФУ | |
dc.relation.startpage | 9883 | |
dc.source.id | SCOPUS00219606-1997-106-23-SID0005107495 |