Nihon Reoroji Gakkaishi
Online ISSN : 2186-4586
Print ISSN : 0387-1533
ISSN-L : 0387-1533
Original Articles
Viscoelastic Relaxation of Linear Polyisoprenes: Examination of Constraint Release Mechanism
Toshiaki SawadaXiuying QiaoHiroshi Watanabe
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2007 Volume 35 Issue 1 Pages 11-20


Linear viscoelastic behavior was examined for a series of binary blends of linear polyisoprenes (PI). These blends contained high molecular weight (M) component chains (probe chains) that were dilute and entangled only with the lower-M matrix chains. The PI probe exhibited the Rouse-like constraint release (CR) relaxation in the matrix chains much shorter than the probe, but this CR-dominance vanished on a moderate increase of the matrix molecular weight because of the competition with other mechanisms (such as reptation). These features are qualitatively similar to, but quantitatively different from, those noted for binary blends of linear polystyrenes (PS): The CR-dominance was more easily achieved in the PI/PI blends than in the PS/PS blends, which suggests that the entanglement dynamics is not uniquely determined by the number of entanglement segments per chain and the relaxation time within this segment but is affected by additional molecular factors such as the local CR gate number considered by Graessley (Adv Polym Sci, 47, 67 (1982)).

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© 2007 The Society of Rheology, Japan
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