scholarly journals Physical aging of polycarbonate far below the glass transition temperature: Evidence for the diffusion mechanism

2004 ◽  
Vol 70 (22) ◽  
Author(s):  
D. Cangialosi ◽  
M. Wübbenhorst ◽  
J. Groenewold ◽  
E. Mendes ◽  
H. Schut ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Aging ◽  
Diffusion Mechanism

scholarly journals Physical Aging Behavior of a Glassy Polyether

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 954
Author(s):  
Xavier Monnier ◽  
Sara Marina ◽  
Xabier Lopez de Pariza ◽  
Haritz Sardón ◽  
Jaime Martin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Aging ◽  
Glassy State ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Narrow Temperature Range ◽  
Glass Forming ◽  
Fast Scanning Calorimetry

The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

Foaming of Polystyrene/Supercritical CO2 in Rapid Decompression and Cooling Process

2006 ◽  
Vol 11-12 ◽  
pp. 761-764
Author(s):  
Xiao Dan Wu ◽  
Yu Cheng Peng
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Diffusion Mechanism ◽  
Gravimetric Method ◽  
Batch Process ◽  
Expansion Ratio ◽  
Cooling Process ◽  
Co2 Diffusion ◽  
Rapid Decompression

Foaming of polystyrene (PS)/ supercritical dioxide system was studied in a batch process in order to achieve a better understanding of supercritical CO2 diffusion mechanism in polymer and foaming condition. In this study, PS sample was treated with CO2 at 5-30 MPa and 40-160°C, soaking times was about 30-120min.Using gravimetric method, the solubility of CO2 in PS was obtained. The study datum shows that the solubility of CO2 in PS increases with increment of pressures, but decreases with the increment of temperature. The sorbed amount of CO2 is from 0.02 % (7MPa,160°C) to 0.11%(30MPa,40°C).The relation of glass transition temperature, volume expansion ratio, cells density of foaming with pressure and temperature also was discussed individually. The glass transition temperature of PS swelled with CO2 is 80°C-95°C, which is lower than the glass transition temperature of pure PS by 10°C-25°C. The cell density increases as the pressure increase, and it decrease as the temperature increase.

Isothermal Physical Aging of Poly(ethyl methacrylate)/Polyhedral Oligomeric Silsequioxanes Nanocomposite Thin Films

2011 ◽  
Vol 287-290 ◽  
pp. 2234-2239 ◽  
Author(s):  
Sil Ro Jin ◽  
Jong Keun Lee
Keyword(s):  
Thin Films ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Film Thickness ◽  
Methyl Methacrylate ◽  
Relaxation Function ◽  
Physical Aging ◽  
Pmma Film ◽  
Nanocomposite Thin Films

The effects of the polyhedral oligomeric silsequioxanes (POSS) in stacked poly(methyl methacrylate) (PMMA) film samples were investigated in two different film thicknesses, ~50 and ~660 nm. The types of the POSS include methacryl-, octaisobutyl-, and octasilane-POSS. The glass transition temperature (Tg) and isothermal physical aging was depressed by the reduction of film thickness. Among POSS molecules used in this work, methacryl-POSS was the greatest effect in both Tgand relaxation enthalpy (DHRelax) due to the physical aging. The Kohlrausch-Williams-Watts (KWW) relaxation function was used to further understand the effect of POSS and film thickness on the physical aging.

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