Modeling volume relaxation of amorphous polymers: Modification of the equation for the relaxation time in the KAHR model

Polymer ◽  
2012 ◽  
Vol 53 (16) ◽  
pp. 3613-3620 ◽  
Author(s):  
Luigi Grassia ◽  
Sindee L. Simon
Keyword(s):  
Relaxation Time ◽  
Amorphous Polymers ◽  
Volume Relaxation

Thermal contraction and volume relaxation of amorphous polymers

1984 ◽  
Vol 23 (4) ◽  
pp. 378-395 ◽  
Author(s):  
R. Greiner ◽  
F. R. Schwarzl
Keyword(s):  
Amorphous Polymers ◽  
Thermal Contraction ◽  
Volume Relaxation

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.

Effects of Aging on Polymerization Kinetics

1990 ◽  
Vol 215 ◽  
Author(s):  
Christopher N. Bowman ◽  
Nikolaos A. Peppas
Keyword(s):  
Relaxation Time ◽  
Theoretical Model ◽  
Light Intensity ◽  
Physical Aging ◽  
Volume Relaxation ◽  
Radical Concentration ◽  
Model Predictions ◽  
Maximum Conversion ◽  
Effects Of Aging ◽  
Crosslinking Reactions

AbstractA theoretical model was developed to describe the physical aging during photopolymerizations and crosslinking reactions of diacrylates and dimethacrylates. The model incorporates the strong coupling between the volume relaxation and the kinetics observed in these reactions. Model predictions are presented for the reaction kinetics, volume relaxation, radical concentration and maximum conversion as a function of light intensity and relaxation time of the polymer.

scholarly journals Volume Relaxation in Amorphous Polymers around Glass-Transition Temperature

1978 ◽  
Vol 10 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Masataka Uchidoi ◽  
Keiichiro Adachi ◽  
Yoichi Ishida
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Amorphous Polymers ◽  
Volume Relaxation
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