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Titolo:
A deuterium NMR study of selectively labeled polybutadiene star polymers
Autore:
Adams, CH; Brereton, MG; Hutchings, LR; Klein, PG; McLeish, TCB; Richards, RW; Ries, ME;
Indirizzi:
Univ Leeds, IRC Polymer Sci & Technol, Leeds LS2 9JT, W Yorkshire, EnglandUniv Leeds Leeds W Yorkshire England LS2 9JT S2 9JT, W Yorkshire, England Univ Durham, Durham DH1 3LE, England Univ Durham Durham England DH1 3LEUniv Durham, Durham DH1 3LE, England
Titolo Testata:
MACROMOLECULES
fascicolo: 19, volume: 33, anno: 2000,
pagine: 7101 - 7106
SICI:
0024-9297(20000919)33:19<7101:ADNSOS>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAGNETIC-RESONANCE; VISCOELASTIC PROPERTIES; TRANSVERSE RELAXATION; BRANCHED POLYMERS; DYNAMICS; RHEOLOGY; NETWORKS; CHAINS; MODEL; ROUSE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
22
Recensione:
Indirizzi per estratti:
Indirizzo: Klein, PG Univ Leeds, IRC Polymer Sci & Technol, Leeds LS2 9JT, W Yorkshire, England Univ Leeds Leeds W Yorkshire England LS2 9JT Yorkshire, England
Citazione:
C.H. Adams et al., "A deuterium NMR study of selectively labeled polybutadiene star polymers", MACROMOLEC, 33(19), 2000, pp. 7101-7106

Abstract

From a combination of tailored synthesis and deuterium NMR free induction decay (FID) measurements, the molecular dynamics of various entanglement sections in four-arm star polybutadienes has been studied. Each arm of the polybutadiene stars has a monodisperse molecular weight of 30 000 g mol(-1), and each has a deuterated sequence of molecular weight 2000 g mol(-1). Thissequence, which corresponds to an entanglement length, has been located atdifferent distances from each arm end, namely one entanglement length fromthe free end, 1/4, 1/2, and 3/4 Of the way down the arm to the star core and at the core. Although the FIDs from the core and near the free end are always distinctly different, the FIDs from the other sections are only clearly distinguishable above ca. 40 degrees C. This is interpreted in terms of the molecular weight corresponding to the longest Rouse mode detectable on the NMR time scale at various temperatures. The deuterium FIDs have been analyzed according to an exact solution for the transverse relaxation, which produces an effective correlation time that increases toward the core of the star and with decreasing temperature.

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Documento generato il 20/09/20 alle ore 04:18:37