TY - JOUR
T1 - Enthalpy recovery of polymeric glasses
T2 - Is the theoretical limiting liquid line reached?
AU - Li, Qingxiu
AU - Simon, Sindee L.
N1 - Funding Information:
The authors would like to acknowledge American Chemical Society Petroleum Research Fund (grant number 39807-AC7) for their financial support to this project.
PY - 2006/6/14
Y1 - 2006/6/14
N2 - Glasses are inherently non-equilibrium materials, and consequently, their properties evolve toward equilibrium in a process known as structural recovery or physical aging. Recently, several authors have suggested that the equilibrium liquid line is not reached even when properties have ceased to evolve. In this work, we present measurements of the enthalpy recovery of polystyrene (PS) at temperatures ranging from 90.0 to 103.0 °C, for aging times up to 200 days. The results are analyzed in the context of the TNM model of structural recovery. In addition, we analyze data in the literature to determine whether enthalpy recovery ceases prior to the material reaching the equilibrium liquid line obtained by extrapolation of the liquid line above Tg. The results suggest that, in fact, the liquid enthalpy line is reached at temperatures below Tg when equilibrium is reached, i.e. when properties cease to evolve.
AB - Glasses are inherently non-equilibrium materials, and consequently, their properties evolve toward equilibrium in a process known as structural recovery or physical aging. Recently, several authors have suggested that the equilibrium liquid line is not reached even when properties have ceased to evolve. In this work, we present measurements of the enthalpy recovery of polystyrene (PS) at temperatures ranging from 90.0 to 103.0 °C, for aging times up to 200 days. The results are analyzed in the context of the TNM model of structural recovery. In addition, we analyze data in the literature to determine whether enthalpy recovery ceases prior to the material reaching the equilibrium liquid line obtained by extrapolation of the liquid line above Tg. The results suggest that, in fact, the liquid enthalpy line is reached at temperatures below Tg when equilibrium is reached, i.e. when properties cease to evolve.
KW - Enthalpy recovery
KW - Polystyrene
KW - TNM/KAHR model
UR - http://www.scopus.com/inward/record.url?scp=33746911952&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2006.04.046
DO - 10.1016/j.polymer.2006.04.046
M3 - Article
AN - SCOPUS:33746911952
VL - 47
SP - 4781
EP - 4788
JO - Polymer
JF - Polymer
SN - 0032-3861
IS - 13
ER -