Abstract
The physical properties of the glass depend on the procedure used to produce the glass. In particular, if the glass is obtained through the variation of external thermodynamic parameters, the specific way in which the parameters are varied (thermodynamic history) has influence on the final properties. In this work, we studied the effect of thermodynamic history on secondary relaxation inside the glassy state on different molecular glass forming, namely, PPGE(poly[(phenyl glycidyl ether)-co-formaldehyde]), 1,18-bis (p methoxyphenyl) cyclohexane (BMPC), poly(propylene glycol)—(PPG400), phenolphthalein-dimethyl-ether(PDE), Poly(vinyl acetate) (PVAc), and poly(bisphenol A-co-epichlorohydrin) glycidyl end-capped (DGEBA). We found secondary relaxation change with thermodynamic history and depends on the value of the activation volume which activation entropy of secondary relaxation inside the glassy state. Also, we found most of the JG secondary relaxation change with thermodynamic history and most of the Non-JG secondary relaxation are not sensitive.
Highlights
The state of the glass depends on the procedure used to produce the glass
We present the study of the influence of thermodynamic history on the secondary process of different molecular glass formers, namely PPGE (poly[(phenyl glycidyl ether)-co-formaldehyde]), 1,18-bis (p methoxyphenyl) cyclohexane (BMPC), poly—(PPG400), phenolphthalein-dimethyl-ether (PDE), Poly(vinyl acetate) (PVAc), and Poly(Bisphenol A-co-epichlorohydrin) glycidyl end-capped (DGEBA)
It is reported that the β-secondary process of PPGE and DGEBA is of the JG type [24, 25], whereas the β-process of PDE and BMPC and the γ-process of PPG400 are non-JG [26, 27]
Summary
The state of the glass depends on the procedure used to produce the glass. In particular, if the glass is obtained through the variation of any external thermodynamic parameters, the specific way in which the parameter is varied (thermodynamic history) influences the molecular arrangement. When motion depends on whole molecule it is designated as the Johari-Goldstein (JG) process In another case, the investigation was performed at high-pressure, using different combinations of pressure and temperature variations. We present the study of the influence of thermodynamic history on the secondary process of different molecular glass formers, namely PPGE (poly[(phenyl glycidyl ether)-co-formaldehyde]), 1,18-bis (p methoxyphenyl) cyclohexane (BMPC), poly (propylene glycol)—(PPG400), phenolphthalein-dimethyl-ether (PDE), Poly(vinyl acetate) (PVAc), and Poly(Bisphenol A-co-epichlorohydrin) glycidyl end-capped (DGEBA). All of these systems present a complex relaxation scenario, with more than one secondary process. A liquid circulator connected to a jacket, wrapped around the pressure room, allowed the control of temperature (353–233 K) within 0.1 K
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