Density Fluctuations near the Glass Transition in Polymers and Low Molecular Weight Liquids

1988 ◽  
pp. 122-137
Author(s):  
G. Meier ◽  
E. W. Fischer
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Density Fluctuations ◽  
Low Molecular Weight

Density fluctuations around the glass-transition of low molecular weight glass-forming liquids

1991 ◽  
Vol 131-133 ◽  
pp. 134-138 ◽  
Author(s):  
E.W Fischer ◽  
G Meier ◽  
T Rabenau ◽  
A Patkowski ◽  
W Steffen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Density Fluctuations ◽  
Low Molecular Weight ◽  
Glass Forming

Glass Transition and Ultrasonic Relaxation in Polystyrene

1996 ◽  
Vol 455 ◽  
Author(s):  
A. Sahnoune ◽  
L. Piché
Keyword(s):  
Molecular Weight ◽  
Relaxation Time ◽  
Glass Transition ◽  
Low Temperatures ◽  
Relaxation Modulus ◽  
Low Molecular Weight ◽  
Relaxation Model ◽  
Fragility Index ◽  
Molecular Weights ◽  
Ultrasonic Relaxation

ABSTRACTWe present measurements of the glass transition and the ultrasonic relaxation modulus in a series of monodisperse polystyrenes. The temperature dependence of the modulus was analyzed using Havriliak-Negami relaxation model (HN) and Vogel-Tammann-Fulcher equation (VTF) for the relaxation time. The results allowed us to determine the fragility index, m, which decreases with increasing molecular weight, Mn. Furthermore, the relaxation time was found to saturate at high molecular weights and varies as Mnp, in the low molecular weight region. The exponent is p≈2 at high temperatures and p ≈ 7 at low temperatures close to Tg.

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