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Tube dynamics in binary polymer blends
DOI:10.1021/ma040080h.png)
摘要
En 中文
Stress relaxation dynamics of entangled linear/linear and short star/linear 1,4-polybutadiene and 1,4-polyisoprene blends are studied using a combination of mechanical rheometry and theory. In binary blends comprised of long linear chains and entangled short star or short linear molecules, we find that relaxation of the faster relaxing short molecules leads to a reduction in shear modulus consistent with expectations for solventlike dilution of the entanglement network in which the slower relaxing long chains diffuse. Terminal relaxation dynamics of the long chains are nonetheless found to be substantially different in blends with short star and short linear molecules. Specifically, while terminal relaxation in linear/linear blends is consistent with expectations for reptation diffusion of the long linear molecules in a uniformly dilated tube, terminal relaxation in the short star/linear blends occur by reptation diffusion of the long chains in an undilated tube. Thus, in the short star/linear blends the longer linear chains appear unable to take advantage of the more dilated network produced by relaxed stars, even when relaxation times of the two species differ by more than 2 orders of magnitude. This finding is inconsistent with expectations from dynamic tube dilation models for polymer blend relaxation. It indicates that architecturally complex molecules exert a longer-lived influence on tube equilibration in blends than anticipated by these models.
Keyword:
ENTANGLED POLYMERS
VISCOELASTIC PROPERTIES
CONSTRAINT-RELEASE
STRESS-RELAXATION
LINEAR-POLYMERS
MELTS
REPTATION
DILATION
RHEOLOGY
BEHAVIOR
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期刊
IF:
5.2
论文数:
3.7W
被引数:
9.4W
机构
暂无机构信息
引用论文
Linear rheology of binary melts from a phenomenological tube model of entangled polymers
JOURNAL OF RHEOLOGY
IF3.2
Viscoelastic and dielectric behavior of entangled blends of linear polyisoprenes having widely separated molecular weights: Test of tube dilation picture
MACROMOLECULES
IF5.2

