The amorphous state: first-principles derivation of the Gordon–Taylor equation for direct prediction of the glass transition temperature of mixtures; estimation of the crossover temperature of fragile glass formers; physical basis of the “Rule of 2/3”

2017 ◽  
Vol 19 (31) ◽  
pp. 20523-20532 ◽  
Author(s):  
Peter J. Skrdla ◽  
Philip D. Floyd ◽  
Philip C. Dell’Orco
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
First Principles ◽  
Amorphous State ◽  
Crossover Temperature ◽  
Broad Application ◽  
Amorphous Phases ◽  
Fields Of Study ◽  
Fragile Glass

Predicting the glass transition and crossover temperatures of pure amorphous phases and mixtures finds broad application across different fields of study.

Miscibility, Isothermal Crystallization/Melting Behavior and Morphology of Poly(Trimethylene Terephthalate)/Poly(Buthylene Terephthalate) Blends

2008 ◽  
Vol 54 ◽  
pp. 243-248 ◽  
Author(s):  
Pongpipat Krutphun ◽  
Pitt Supaphol
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Amorphous State ◽  
Minor Component ◽  
The Body ◽  
Nucleation Theory ◽  
Melting Point Depression ◽  
Melt Crystallization ◽  
Trimethylene Terephthalate

Blends of poly(trimethylene terephthalate) (PTT) and poly(buthylene terephthalate) (PBT) in the amorphous state were miscible in all of the blend compositioins studied, as evidenced by a single, composition-dependent glass-transition temperature observed for each blend composition. The variation in the glass-transition temperature was well-predicted by the Gordon- Taylor equation, with the fitting parameter being 1.37. The cold-crystallization (peak) temperature increased with increasing PBT content in the blends. The subsequent melting endotherms after melt crystallization exhibited melting point depression behavior in which the observed melting temperatures decreased with an increasing amount of minor component of the blends. LHW and NLHW were used to determine the equilibrium melting temperature of the blends. The values of the overall crystallization rate parameters for these blends were all found to increase with decreasing crystallization temperature, suggesting that these blends crystallized at low temperatures faster than that at high temperatures. As the content of PBT was further increased, these values dramatically decreased. This result is similar to that observed in the growth rate. From LH secondary nucleation theory, PTT ,PBT and their blends showed the transition temperatures between regime III and II about 194oC. Banded spherulites were observed for PTT/PBT blends. The spacing of bands of PTT increases with increasing Tc. The body of spherulite texture is more open with increasing PBT content. In addition, the boundary of spherulite is also changed with composition.

scholarly journals Crystals in hard candies

2011 ◽  
Vol 21 (No. 5) ◽  
pp. 185-191 ◽  
Author(s):  
I. Šmídová ◽  
J. Čopíková ◽  
M. Maryška ◽  
M.A. Coimbra
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Moisture Content ◽  
Glassy State ◽  
Amorphous State ◽  
Scanning Calorimetry ◽  
Fisher Method ◽  
Maltose Syrup

The main purpose of the contribution presented here is the study of the glassy state and the presence of crystals in hard candies. Hard candies are non-chocolate sweets usually made of sucrose and glucose or of maltose syrup. They can also be made of alditols, used in sugar-free hard candies. In hard candies, carbohydrates or alditols are in amorphous state. Crystallisation in the glassy state of hard candies occurs as a result of a bad formulation, processing or storage and can be detrimental to the product quality. Differential scanning calorimetry was used to determine the glass transition temperature T<sub>g</sub> and the amount of crystals. Polarising microscopy was used to show the undesirable presence of crystals in samples of hard candies. The carbohydrates composition of the samples was determined by HPLC and the moisture content in each sample was evaluated by Karl Fisher method. &nbsp;

Microstructure and Microhardness in Current Annealed Fe65.5Cr4Mo4Ga4P12C5B5.5 Bulk Metallic Glass

2007 ◽  
Vol 555 ◽  
pp. 521-526 ◽  
Author(s):  
N. Mitrović ◽  
B. Čukić ◽  
Branka Jordović ◽  
Stefan Roth ◽  
M. Stoica
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Amorphous State ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Nominal Composition ◽  
Liquid Region ◽  
Scanning Calorimetry

The rods of Fe-based bulk metallic glasses with the nominal composition Fe65.5Cr4Mo4Ga4P12C5B5.5 were cast by melt injection into 1.5 and 1.8 mm diameter copper molds. The thermal stability, microstructure and crystallization behavior were investigated by differential scanning calorimetry, optical micrography and X-ray diffraction, respectively. The wide supercooled liquid region between crystallization temperature (Tx) and glass transition temperature (Tg) in the as-cast state Tx=Tx-Tg=60 K, as well as the high value of reduced glass transition temperature Trg=Tg/Tl=0.567 (Tl is liquidus temperature) approves enhanced thermal stability of the alloy against crystallization. In the as-cast “XRD-amorphous” state, microhardness HV1=742 was observed. Multistep current annealing thermal treatments were performed for structural relaxation. After applying high enough heating power per square area (PS ≥ 6 W/cm2), intensive crystallization of the samples characterized by appearance of several iron-metalloid compounds (Fe5C2, Fe3Ga4, Fe63Mo37 and Mo12Fe22C10) was observed. The microstructure changes after crystallization bring about differences in the microhardness values. The areas of still present amorphous matrix are with increased value HV1=876, but a remarkable decrease to HV1=323 was observed in precipitated crystallized zone that propagate along inner part of cylinders.

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