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Titolo:
SYNTHESIS AND DYNAMIC RHEOLOGICAL BEHAVIOR OF POLYBUTADIENE STAR POLYMERS
Autore:
ADAMS CH; HUTCHINGS LR; KLEIN PG; MCLEISH TCB; RICHARDS RW;
Indirizzi:
UNIV DURHAM,IRC POLYMER SCI & TECHNOL DURHAM DH1 3LE ENGLAND UNIV DURHAM,IRC POLYMER SCI & TECHNOL DURHAM DH1 3LE ENGLAND UNIV LEEDS LEEDS LS2 9JT W YORKSHIRE ENGLAND
Titolo Testata:
Macromolecules
fascicolo: 17, volume: 29, anno: 1996,
pagine: 5717 - 5722
SICI:
0024-9297(1996)29:17<5717:SADRBO>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
VISCOELASTIC PROPERTIES; SHAPED POLYMERS; MELTS; MODEL;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
13
Recensione:
Indirizzi per estratti:
Citazione:
C.H. Adams et al., "SYNTHESIS AND DYNAMIC RHEOLOGICAL BEHAVIOR OF POLYBUTADIENE STAR POLYMERS", Macromolecules, 29(17), 1996, pp. 5717-5722

Abstract

Polybutadiene star polymers, of nominal functionality 3, 4, 8 and 12,all with arm lengths of approximately 30 000 g mol(-1), have been synthesized using chlorosilane coupling agents. Dynamic mechanical studies have been carried out using parallel-plate rheometry at various temperatures, and the data frequency-temperature shifted to produce mastercurves. Fits to the Ball-McLeish constraint release theory indicate an effective entanglement molecular weight somewhat higher than the literature value for a linear polymer. This has been interpreted by considering a dilution of constraints effect caused by the Rouse diffusion of the terminal section of the star arm, leading to a predicted modified entanglement molecular weight similar to that found experimentally. Evidence for the Rouse-like behavior of the terminal section has beenobtained from deuterium NMR spectra of a selectively deuterated sample. The presence of small amounts of residual linear chains is shown tobe responsible for a further dilution of entanglements. An extension of the theoretical fits to include the high-frequency Rouse mode spectrum shows a divergence between theory and experiment which is indicative of the onset of the glass transition.

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Documento generato il 22/10/20 alle ore 08:51:57