Relaxation processes and intermolecular interactions in PVME hydrogels in sub-zero temperatures: Glass transition and pre-melting of ice

Polymer ◽  
2012 ◽  
Vol 53 (1) ◽  
pp. 161-168 ◽  
Author(s):  
Marcin Pastorczak ◽  
Michael Wübbenhorst ◽  
Gustavo Dominguez-Espinosa ◽  
Lidia Okrasa ◽  
Marek Pyda ◽  
...  
Keyword(s):  
Glass Transition ◽  
Intermolecular Interactions ◽  
Relaxation Processes

Impact of cyclic topology: odd–even glass transition temperatures and fluorescence quantum yields in molecularly-defined macrocycles

2017 ◽  
Vol 8 (17) ◽  
pp. 2686-2692 ◽  
Author(s):  
Kun Li ◽  
Ganquan Jiang ◽  
Feng Zhou ◽  
Lishan Li ◽  
Zhengbiao Zhang ◽  
...  
Keyword(s):  
Glass Transition ◽  
Intermolecular Interactions ◽  
Topological Structure ◽  
Quantum Yields ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Fluorescence Quantum Yields

The topological structure of cyclic-TPEn+1 (n = 1–6) induces odd–even effects on the Tg and AIE behavior, arising from the alternation of intermolecular interactions.

Effects of Complexation on the Glass Transition Temperature of Polymers

1990 ◽  
Vol 215 ◽  
Author(s):  
Michael F. Roberts ◽  
Samson A. Jenekhe
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Hydrogen Bonds ◽  
Intermolecular Interactions ◽  
Lewis Acid ◽  
Dominant Effect ◽  
Intermolecular Hydrogen Bonds ◽  
Aromatic Polyamides ◽  
Rigid Chain

AbstractThe effects of Lewis acid complexation on the glass transition temperature (Tg) of several polymers with strong intermolecular interactions was investigated. The decrease in the Tg due to GaCl3 complexation of aliphatic and aromatic polyamides was 40–600° C and 148° C, respectively, and was shown to originate from scission of the intermolecular hydrogen bonds. The reduction in the Tg due to GaCl3 complexation of rigid–chain polymers was greater that 325° C and can be explained by the mitigation of the otherwise strong van der Waals forces in the pristine polymers. Thus, the dominant effect of intermolecular interactions on the Tg of several polymers has been probed by Lewis acid complexation.

Glass Transition and Relaxation Processes in Supercooled Water

2004 ◽  
Vol 93 (24) ◽  
Author(s):  
Silvina Cerveny ◽  
Gustavo A. Schwartz ◽  
Rikard Bergman ◽  
Jan Swenson
Keyword(s):  
Glass Transition ◽  
Supercooled Water ◽  
Relaxation Processes

scholarly journals Pharmaceutical Amorphous Organic Materials Characterization by Using the Differential Scanning Calorimetry and Dynamic Mechanical Analysis

2011 ◽  
Vol 6 (2) ◽  
pp. 91-95
Author(s):  
Ion Dranca ◽  
Igor Povar ◽  
Tudor Lupascu
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Dynamic Mechanical Analysis ◽  
Mechanical Analysis ◽  
Relaxation Processes ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Β Relaxation

This research has been carried out in order to demonstrate the use of differential scanning calorimetry (DSC) in detecting and measuring α- and β-relaxation processes in amorphous pharmaceutical systems. DSC has been employed to study amorphous samples of poly (vinylpyrrolidone) (PVP), indomethacin (InM), and ursodeoxycholic acid (UDA) that are annealed at temperature (Ta) around 0.8 of their glass transition temperature (Tg). Dynamic mechanical analysis (DMA) is used to measure β- relaxation in PVP. Yet, the DSC has been used to study the glassy indomethacin aged at 0 and -10 oC for periods of time up to 109 and 210 days respectively. The results demonstrate the emergence of a small melting peak of the α-polymorph after aging for 69 days at 0°C and for 147 days at -10°C (i.e., ~55°C below the glass transition temperature) that provides evidence of nucleation occurring in the temperature region of the β-relaxation.

scholarly journals PACMAN PERCOLATION AND THE GLASS TRANSITION

Fractals ◽  
2013 ◽  
Vol 21 (03n04) ◽  
pp. 1350021 ◽  
Author(s):  
RAFFAELE PASTORE ◽  
MASSIMO PICA CIAMARRA ◽  
ANTONIO CONIGLIO
Keyword(s):  
Monte Carlo ◽  
Relaxation Time ◽  
Glass Transition ◽  
Monte Carlo Simulations ◽  
Relaxation Process ◽  
Time Scales ◽  
Relaxation Processes ◽  
Percolation Transition ◽  
Glass Model ◽  
Different Time Scales

We investigate via Monte Carlo simulations the kinetically constrained Kob-Andersen lattice glass model showing that, contrary to current expectations, the relaxation process and the dynamical heterogeneities seems to be characterized by different time scales. Indeed, we found that the relaxation time is related to a reverse percolation transition, whereas the time of maximum heterogeneity is related to the spatial correlation between particles. This investigation leads to a geometrical interpretation of the relaxation processes and of the different observed time scales.

Photoexcitations in Oligothiophenes: The Role of Conformation Mobility and Intermolecular Interactions.

1999 ◽  
Vol 598 ◽  
Author(s):  
Chiara Botta ◽  
Silvia Destri ◽  
William Porzio ◽  
Gianni Bongiovanni ◽  
Andrea Mura ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solid State ◽  
Intermolecular Interactions ◽  
Photophysical Properties ◽  
Supramolecular Organization ◽  
Relaxation Processes ◽  
Chain Packing ◽  
Backbone Conformation ◽  
Packing Arrangement

ABSTRACTThe optical properties of substituted and unsubstituted oligothiophenes are analysed with respect to their supramolecular organization in the solid state. The spectra typical of the isolated molecules are obtained by reducing the intermolecular interactions by both lateral chain substitution and by inclusion in a host organic crystal. The photophysical properties of the weakly interacting oligothiophenes are strongly influenced by their backbone conformation and conformational mobility. Oligomers included in the channels of a guest crystal show fast torsional relaxation processes during the photoexcitation. Powders of β-substituted oligomers display optical properties dependent on the conformation of their particular chain packing arrangement.

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