scholarly journals Physical stability of drugs after storage above and below the glass transition temperature: Relationship to glass-forming ability

2015 ◽  
Vol 495 (1) ◽  
pp. 312-317 ◽  
Author(s):  
Amjad Alhalaweh ◽  
Ahmad Alzghoul ◽  
Denny Mahlin ◽  
Christel A.S. Bergström
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Stability ◽  
Glass Forming Ability ◽  
Temperature Relationship ◽  
Glass Forming

scholarly journals Long-Term Physical (In)Stability of Spray-Dried Amorphous Drugs: Relationship with Glass-Forming Ability and Physicochemical Properties

Pharmaceutics ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 425 ◽  
Author(s):  
Edueng ◽  
Bergström ◽  
Gråsjö ◽  
Mahlin
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physicochemical Properties ◽  
Physical Stability ◽  
Glass Forming Ability ◽  
Melt Quenching ◽  
Glass Forming ◽  
Spray Dried

This study shows the importance of the chosen method for assessing the glass-forming ability (GFA) and glass stability (GS) of a drug compound. Traditionally, GFA and GS are established using in situ melt-quenching in a differential scanning calorimeter. In this study, we included 26 structurally diverse glass-forming drugs (i) to compare the GFA class when the model drugs were produced by spray-drying with that when melt-quenching was used, (ii) to investigate the long-term physical stability of the resulting amorphous solids, and (iii) to investigate the relationship between physicochemical properties and the GFA of spray-dried solids and their long-term physical stability. The spray-dried solids were exposed to dry (<5% RH) and humid (75% RH) conditions for six months at 25 °C. The crystallization of the spray-dried solids under these conditions was monitored using a combination of solid-state characterization techniques including differential scanning calorimetry, Raman spectroscopy, and powder X-ray diffraction. The GFA/GS class assignment for 85% of the model compounds was method-dependent, with significant differences between spray-drying and melt-quenching methods. The long-term physical stability under dry condition of the compounds was predictable from GFA/GS classification and glass transition and crystallization temperatures. However, the stability upon storage at 75% RH could not be predicted from the same data. There was no strong correlation between the physicochemical properties explored and the GFA class or long-term physical stability. However, there was a slight tendency for compounds with a relatively larger molecular weight, higher glass transition temperature, higher crystallization temperature, higher melting point and higher reduced glass transition temperature to have better GFA and better physical stability. In contrast, a high heat of fusion and entropy of fusion seemed to have a negative impact on the GFA and physical stability of our dataset.

Glass-forming ability of Pr–(Cu,Ni)–Al alloys in eutectic system

2003 ◽  
Vol 18 (3) ◽  
pp. 664-671 ◽  
Author(s):  
Y. Zhang ◽  
H. Tan ◽  
H. Z. Kong ◽  
B. Yao ◽  
Y. Li
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Eutectic Composition ◽  
Solidus Temperature ◽  
Eutectic Point ◽  
Glass Forming Ability ◽  
Al Alloys ◽  
Eutectic System ◽  
Glass Forming

A eutectic point in Pr-rich Pr-(Cu,Ni)-Al alloys was experimentally determined by measuring the solidus temperature (Tm) and liquidus temperature (T1). It was found that Pr68(Cu0.5Ni0.5)25Al7 (at.%) is at the eutectic composition in the pseudoternary Pr–(Cu0.5Ni0.5)–Al alloys. The alloy Pr68(Cu0.5Ni0.5)25Al7 exhibits better glass-forming ability (GFA) than the ternary eutectic alloy Pr68Cu25Al7. However, the best GFA was obtained at an off-eutectic composition (Pr54[Cu0.5Ni0.5]30Al16) in the Pr–(Cu0.5Ni0.5)–Al alloys, which can be formed in fully amorphous rods with diameter of 1.5 mm by copper mold casting. Moreover, the glass-transition temperature Tg increases quickly (from 367 to 522 K) with the increasing of the Al content (from 3 to 27 at.%). The deviation of the best GFA composition from the eutectic point [Pr68(Cu0.5Ni0.5)25Al7] was explained in terms of the asymmetric coupled eutectic zone, the competition between growth of crystalline phase and formation of amorphous, and the higher glass-transition temperature Tg on the hypereutectic side.

A new Mg65Cu7.5Ni7.5Zn5Ag5Y10 bulk metallic glass with strong glass-forming ability

2003 ◽  
Vol 18 (10) ◽  
pp. 2288-2291 ◽  
Author(s):  
H. Ma ◽  
E. Ma ◽  
J. Xu
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Glass Forming Ability ◽  
Copper Mold ◽  
Glass Forming ◽  
Copper Mold Casting ◽  
Mold Casting

We report a new Mg-based bulk metallic glass-forming alloy: Mg65Cu7.5Ni7.5Zn5 Ag5Y10. The alloy exhibits a glass-forming ability significantly stronger than all previously discovered Mg-based glass formers. Fully glassy rods 9 mm in diameter can be obtained by using copper mold casting. The critical cooling rate for glass formation was estimated to be <50 Ks−1. The reduced glass-transition temperature (Trg) of the glass was determined to be 0.59.

Rare Earth Elements on Glass-Forming Ability and Thermal Stability of Cu-Zr-Al Metallic Glass

2011 ◽  
Vol 688 ◽  
pp. 426-430 ◽  
Author(s):  
Yan Fang Wang ◽  
Li Li ◽  
Chuan Sun ◽  
Qing Long Lu ◽  
Zhi Qiang Shi
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Rare Earth ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Rare Earth Elements ◽  
Glass Forming Ability ◽  
Glass Forming ◽  
Thermal Stability Of

The rare earth elements (RE= Y, Sm, La, Ce) were used as alloying materials in Cu50Zr45Al5BMG, and their influences on the glass-forming ability and thermal stability were studied in this paper. All the samples remained in full metallic glass state with minor additions of Y, Sm and La. Increasing the amount of RE additions, the Cu10Zr7and Zr2Cu phases precipitated and glass transition temperatureTgand crystallization temperatureTxsignificantly decreased. The reduced glass transition temperature Trg=Tg/Tlranged from 0.592 to 0.611 and the γ parameter ranged from 0.393 to 0.409.

Unraveling the interplay between hydrogen bonding and rotational energy barrier to fine-tune the properties of triazine molecular glasses

2016 ◽  
Vol 18 (3) ◽  
pp. 1681-1692 ◽  
Author(s):  
Audrey Laventure ◽  
Guillaume De Grandpré ◽  
Armand Soldera ◽  
Olivier Lebel ◽  
Christian Pellerin
Keyword(s):  
Hydrogen Bonding ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Energy Barrier ◽  
Glass Forming Ability ◽  
Rotational Energy ◽  
Molecular Glasses ◽  
Glass Forming ◽  
Fine Tune

Mexylaminotriazine derivatives form molecular glasses with outstanding glass-forming ability (GFA), glass kinetic stability (GS), and tunable glass transition temperature. This work establishes key molecular parameters for efficient glass engineering.

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