scholarly journals Dynamics of polycarbonate far below the glass transition temperature:  A positron annihilation lifetime study

2004 ◽  
Vol 69 (13) ◽  
Author(s):  
D. Cangialosi ◽  
M. Wübbenhorst ◽  
H. Schut ◽  
A. van Veen ◽  
S. J. Picken
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Positron Annihilation ◽  
Positron Annihilation Lifetime

Free Volumes in Polymer Nanocomposites

2008 ◽  
Vol 607 ◽  
pp. 177-179 ◽  
Author(s):  
Hong Min Chen ◽  
L. James Lee ◽  
Jin Tao Yang ◽  
Xiao Hong Gu ◽  
Yan Ching Jean
Keyword(s):  
Carbon Dioxide ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Positron Annihilation ◽  
Polymer Nanocomposites ◽  
Carbon Nanofiber ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Combination Effect ◽  
Positron Annihilation Lifetime

We have employed positron annihilation lifetime spectroscopy to measure the free volumes in nanocomposites of polystyrene with addition of carbon nanofiber (CNF) and carbon dioxide as a function of composition and of temperature. We found that the glass transition temperature (Tg) increases as a function of CNF compositions but significantly decreases as the exposure of CO2. We also investigate the combination effect of CNF and CO2 and found that the CO2 significantly weakens the bonding between PS and CNF interfaces. The Tg changes are compared with DSC.

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