Viscoelastic properties of amorphous polymers. 5. A coupling model analysis of the thermorheological complexity of polyisobutylene in the glass-rubber softening dispersion

1997 ◽  
Vol 35 (4) ◽  
pp. 599-614 ◽  
Author(s):  
K. L. Ngai ◽  
D. J. Plazek ◽  
A. K. Rizos
Keyword(s):  
Viscoelastic Properties ◽  
Coupling Model ◽  
Amorphous Polymers ◽  
Model Analysis ◽  
Thermorheological Complexity

Viscoelastic properties of amorphous polymers 3: low molecular weight poly(methylphenylsiloxane)

1994 ◽  
Vol 272 (11) ◽  
pp. 1430-1438 ◽  
Author(s):  
D. J. Plazek ◽  
C. A. Bero ◽  
S. Neumeister ◽  
G. Floudas ◽  
G. Fytas ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Viscoelastic Properties ◽  
Amorphous Polymers ◽  
Low Molecular Weight

Mechanical Relaxation Studies of Sub-Rouse Modes in Amorphous Polymers

2012 ◽  
Vol 184 ◽  
pp. 52-59 ◽  
Author(s):  
Xue Bang Wu ◽  
Hua Guang Wang ◽  
Chang Song Liu ◽  
Zhen Gang Zhu
Keyword(s):  
Relaxation Time ◽  
Coupling Model ◽  
Amorphous Polymers ◽  
Large Temperature ◽  
Mechanical Relaxation ◽  
Segmental Motion ◽  
Mechanical Spectroscopy ◽  
Segmental Dynamics ◽  
Frequency Scale ◽  
Segmental Relaxation

Mechanical spectroscopy is a powerful tool for the investigation of molecular dynamics of amorphous polymers over a large temperature range and frequency scale. In this work, by using high precision shear mechanical spectroscopy tool, we have investigated the segmental dynamics from local segmental relaxation to sub-Rouse modes in a series of amorphous polymers. We have demonstrated the existence of sub-Rouse modes slower than the local segmental motion in amorphous polymers. The sub-Rouse modes exhibit a similar change of dynamics at the same temperature TB ~1.2 Tg, as the local segmental relaxation through the temperature dependence of relaxation time and relaxation strength. Furthermore, the crossover relaxation time of the sub-Rouse modes at TB is almost the same for all the polymers investigated, i.e. τα'(TB) = 10-1±0.5 s, which is independent of molecular weight and molecular structure. This remarkable finding indicates that solely the time scale of the relaxation determines the change in dynamics of the sub-Rouse modes. According to the coupling model, the crossover is suggested to be caused by the onset of strong intermolecular cooperativity below TB. Hence the results suggest that the sub-Rouse modes and their properties are generally found in amorphous polymers by mechanical spectroscopy, and reveal the cooperative nature of the sub-Rouse modes.

scholarly journals Viscoelastic properties of polymers. 4. Thermorheological complexity of the softening dispersion in polyisobutylene

1995 ◽  
Vol 28 (19) ◽  
pp. 6432-6436 ◽  
Author(s):  
D. J. Plazek ◽  
I.-C. Chay ◽  
K. L. Ngai ◽  
C. M. Roland
Keyword(s):  
Viscoelastic Properties ◽  
Thermorheological Complexity

Concomitant Changes in Viscoelastic Properties and Amorphous Polymers during the Hydrothermal Treatment of Hardwood and Softwood

2009 ◽  
Vol 57 (15) ◽  
pp. 6830-6837 ◽  
Author(s):  
Carole Assor ◽  
Vincent Placet ◽  
Brigitte Chabbert ◽  
Anouck Habrant ◽  
Catherine Lapierre ◽  
...  
Keyword(s):  
Hydrothermal Treatment ◽  
Viscoelastic Properties ◽  
Amorphous Polymers

Coupling model analysis of polymer dynamics in solution: Probe diffusion and viscosity

1996 ◽  
Vol 105 (18) ◽  
pp. 8385-8397 ◽  
Author(s):  
K. L. Ngai ◽  
George D. J. Phillies
Keyword(s):  
Coupling Model ◽  
Model Analysis ◽  
Polymer Dynamics
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