Glasses with Strong Calorimetric .beta.-Glass Transitions and the Relation to the Protein Glass Transition Problem

1994 ◽  
Vol 98 (37) ◽  
pp. 9345-9349 ◽  
Author(s):  
J. Fan ◽  
E. I. Cooper ◽  
C. A. Angell
Keyword(s):  
Glass Transition ◽  
Glass Transitions ◽  
Transition Problem ◽  
Protein Glass Transition

Multiple Glass Transitions in Butadiene—Acrylonitrile Copolymers. II. Formation of Incompatible Phases during Copolymerization

1973 ◽  
Vol 46 (4) ◽  
pp. 1087-1102 ◽  
Author(s):  
A. H. Jorgensen ◽  
L. A. Chandler ◽  
E. A. Collins
Keyword(s):  
Glass Transition ◽  
Published Data ◽  
Transition Temperatures ◽  
Glass Transitions ◽  
Glass Transition Temperatures ◽  
Mechanical Measurements ◽  
Nitrile Rubbers ◽  
Polymer Compatibility ◽  
Two Phases ◽  
Acrylonitrile Copolymers

Abstract Differential Thermal Analysis and Dynamic Mechanical measurements show that the presence of two glass transition temperatures in nitrile rubbers is not unusual. Two glass transition temperatures occur in all commercial non-crosslinked butadiene-acrylonitrile rubbers of less than 35 per cent acrylonitrile even though they have gone previously undetected. We have investigated the changes in composition and glass transition temperatures during the course of the copolymerization. The composition versus conversion results were in agreement with previously published data. Fractionation and polymer-polymer compatibility experiments were used to demonstrate the presence of two incompatible phases of different acrylonitrile content, corresponding to the glass transitions of the original co-polymer. The mechanism for the formation of these two phases is discussed.

Glass Transitions in Polymers

1970 ◽  
Vol 43 (1) ◽  
pp. 95-155 ◽  
Author(s):  
M. C. Shen ◽  
A. Eisenberg
Keyword(s):  
Glass Transition ◽  
The Other ◽  
Glass Transitions ◽  
Thermodynamic Process ◽  
Rate Effects ◽  
Complicated Process ◽  
Classical Paper ◽  
Second Order Transition ◽  
Considerable Controversy ◽  
The Many

Abstract We hope that the preceding presentation has made it clear that the glass transition is not a simple phenomenon, but a very complicated process which is still not understood in all of its ramifications. The nature of the glass transition temperature (Tg), to begin with, has been the source cf considerable controversy for many years. The observation of its rate effects, on the other hand, and its similarity to second-order transition, on the other, has caused much confusion. It is not until recently that there is promise for reconciliation. It appears at present that Tg is what one experimentally observes when the material is on its “slow boat” to T2 In other words, Tg is a kinetic manifestation of a thermodynamic process (T2). There is, in fact, no inherent controversy between these two views, since each explains one aspect of the “many-faced” transition. The solution of this problem was actually alluded to in the classical paper of Kauzmann, although it was not recognized as such. The credit of explicit clarification goes to Gibbs and DiMarzio, who first argued the case in quantitative terms.

scholarly journals Translational Hydration Water Dynamics Drives the Protein Glass Transition

2003 ◽  
Vol 85 (3) ◽  
pp. 1871-1875 ◽  
Author(s):  
Alexander L. Tournier ◽  
Jiancong Xu ◽  
Jeremy C. Smith
Keyword(s):  
Glass Transition ◽  
Water Dynamics ◽  
Hydration Water ◽  
Protein Glass Transition

Effects of chemical composition and mean coordination number on glass transitions in Ge–Sb–Se glasses

2017 ◽  
Vol 31 (36) ◽  
pp. 1750342 ◽  
Author(s):  
Wen-Hou Wei
Keyword(s):  
Glass Transition ◽  
Chemical Composition ◽  
Coordination Number ◽  
Structural Phase ◽  
Stoichiometric Composition ◽  
Glass Transitions ◽  
Fragility Index ◽  
Scanning Calorimetry ◽  
Transition Formula ◽  
The Mean

Glass transitions in the Ge–Sb–Se glasses were investigated by means of differential scanning calorimetry (DSC) under non-isothermal conditions. The glass transition temperature [Formula: see text], activation energy of glass transition [Formula: see text], and fragility index as functions of the mean coordination number (MCN) and atomic percent of Ge were examined. The maximum value of [Formula: see text] in each group of the glasses occurred at the chemically stoichiometric composition, suggesting a glass transition threshold. The [Formula: see text] and fragility index were calculated from the heating rate dependence of [Formula: see text]. Both [Formula: see text] and fragility index show the minima at MCN = 2.4 which can be attributed to the structural phase transition of a covalently glassy network at MCN = 2.4. The analysis of the experimental results suggests that both the chemical composition and MCN have significant effects on the glass transitions in Ge–Sb–Se glasses.

Differential Scanning Calorimetry (DSC) Analysis of Abaca Fibre (Musa Textile Nee) Reinforced High Impact Polystyrene (HIPS) Composites

2011 ◽  
Vol 295-297 ◽  
pp. 929-933 ◽  
Author(s):  
E.H. Agung ◽  
S.M. Sapuan ◽  
M.M.H. Megat Ahmad ◽  
H.M.D.K. Zaman ◽  
U. Mustofa
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Optimum Condition ◽  
Amorphous State ◽  
Heat Content ◽  
High Impact ◽  
Glass Transitions ◽  
Scanning Calorimetry ◽  
High Impact Polystyrene

Differential scanning calorimetry (DSC) was used to study the thermal behaviour of abaca fibre reinforced high impact polystyrene (HIPS) composites. Thermal analysis is based upon the detection of changes in the heat content (enthalpy) and the glass transition temperature (Tg) of optimum condition of abaca fibre reinforced HIPS composites. In this research, glass transitions temperature (Tg) of neat HIPS occurred below the Tg of optimum condition of composites as the temperature of an amorphous state. The endothermic peak of composites was in to range 430-435°C including neat HIPS and it observed that enthalpy of abaca fibre reinforced HIPS composites yielded below the neat HIPS 748.79 J/g.

Recent Advances in Glass Transitions in Polymers

1970 ◽  
Vol 43 (1) ◽  
pp. 156-170 ◽  
Author(s):  
A. Eisenberg ◽  
M. Shen
Keyword(s):  
Glass Transition ◽  
Present Article ◽  
Progress Report ◽  
Previous Article ◽  
Glass Transitions ◽  
The Past ◽  
Recent Advances ◽  
Made In

Abstract Since the publication of our review “Glass Transition in Polymers” in 1966, a number of interesting advances have been made in this field. The present article is intended to be an addendum to this review, reporting the progress that has been made by various workers during the past three years. In addition, a number of topics were not covered in the previous article due to the relatively incomplete understanding at that time. These will now be discussed. This is not because these topics are at present fully understood. Rather, we hope it will serve as a progress report to stimulate further interest in areas where further work is needed. The numbering systems and notations in this paper will follow those in the previous article for the sake of continuity.

Sorption Isotherm, Glass Transitions and State Diagram for Freeze-dried Plum Skin and Pulp

2006 ◽  
Vol 12 (3) ◽  
pp. 181-187 ◽  
Author(s):  
V. R. Nicoletti Telis ◽  
P. J. do Amaral Sobral ◽  
J. Telis-Romero
Keyword(s):  
Glass Transition ◽  
Moisture Content ◽  
Sorption Isotherm ◽  
State Diagram ◽  
Transition Curve ◽  
Glass Transitions ◽  
Water Addition ◽  
Scanning Calorimetry ◽  
Freeze Dried ◽  
The Matrix

Differential scanning calorimetry (DSC) was used to determine phase transitions of freeze-dried plums. Samples at low and intermediate moisture contents, were conditioned by adsorption at various water activities (0.11≤aw≤0.90) at 25°C, whereas in the high moisture content region (aw>0.90) samples were obtained by direct water addition, with the resulting sorption isotherm being well described by the Guggenheim-Anderson-deBoer (GAB) model. Freeze-dried samples of separated plum skin and pulp were also analysed. At aw≤0.75, two glass transitions were visible, with the glass transition temperature (Tg) decreasing with increasing aw due to the water plasticising effect. The first Tg was attributed to the matrix formed by sugars and water. The second one, less visible and less plasticised by water, was probably due to macromolecules of the fruit pulp. The Gordon-Taylor model represented satisfactorily the matrix glass transition curve for aw≤0.90. In the higher moisture content range Tg remained practically constant around Tg′ (−57.5°C). Analysis of the glass transition curve and the sorption isotherm indicated that stability at a temperature of 25°C, would be attained by freeze dried plum at a water activity of 0.04, corresponding to a moisture content of 12.9% (dry basis).

scholarly journals Decoupling between calorimetric and dynamical glass transitions in high-entropy metallic glasses

2021 ◽  
Author(s):  
Jiang Jing ◽  
Zhen Lu ◽  
Jie Shen ◽  
Takeshi Wada ◽  
Hidemi Kato ◽  
...  
Keyword(s):  
Glass Transition ◽  
Metallic Glasses ◽  
Materials Science ◽  
Configurational Entropy ◽  
Mechanical Analysis ◽  
Glass Transitions ◽  
Solid State Physics ◽  
High Entropy ◽  
Sluggish Diffusion ◽  
Mechanical Performances

Abstract Glass transition is one of the unresolved critical issues in solid-state physics and materials science, during which a viscous liquid is frozen into a solid or structurally arrested state. On account of the uniform arrested mechanism, the calorimetric glass transition temperature (Tg) always follows the same trend as the dynamical glass transition (or α-relaxation) temperature (Tα) determined by dynamic mechanical analysis (DMA). Here, we explored the correlations between the calorimetric and dynamical glass transitions of three prototypical high-entropy metallic glasses (HEMGs) systems. We found that the HEMGs present a depressed dynamical glass transition phenomenon, i.e. HEMGs with moderate calorimetric Tg represent the highest Tα and the maximum activation energy. These decoupled glass transitions from thermal and mechanical measurements reveal the effect of high configurational entropy on the structure and dynamics of supercooled liquids and metallic glasses, which are associated with sluggish diffusion and decreased dynamic and spatial heterogeneities from high mixing entropy. The results have important implications in understanding the entropy effect on the structure and properties of metallic glasses for designing new materials with plenteous physical and mechanical performances.

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