Degradation Rate of Lyophilized Insulin, Exhibiting an Apparent Arrhenius Behavior around Glass Transition Temperature Regardless of Significant Contribution of Molecular Mobility

2006 ◽  
Vol 95 (12) ◽  
pp. 2684-2691 ◽  
Author(s):  
Sumie Yoshioka ◽  
Tamaki Miyazaki ◽  
Yukio Aso
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Molecular Mobility ◽  
Degradation Rate ◽  
Significant Contribution ◽  
Arrhenius Behavior

Study on Glass Transition Temperature of Polyvinylamine Hydrochloride

2011 ◽  
Vol 217-218 ◽  
pp. 1066-1069 ◽  
Author(s):  
Hong Chi Zhao ◽  
Qi Li ◽  
Li Bin Bai ◽  
Fan Huang
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Differential Scanning Calorimeter ◽  
Degradation Rate ◽  
Average Molecular Weight ◽  
Weight Average Molecular Weight ◽  
Dsc Curves

Polyvinylamine (PVAm) was synthesized by Hofmann degradation of polyacrylamide (PAM). The thermal properties of the Polyvinylamine hydrochloride (PVAm•HCl) were studied by differential scanning calorimeter (DSC). The degradation rate (a) decreased with increasing weight-average molecular weight (Mw) of PAM and decreasing amount of NaOH, and a were the better values when the concentration of PAM was 5% and the amount of NaClO was 10 mL. DSC curves showed that the glass transition temperature (Tg) of PVAm•HCl increased with increasing Mw of PAM, concentration of NaClO and decreasing concentration of NaOH. Tg of PVAm•HCl appeared the minimum value when the concentration of PAM was 5.0%.

scholarly journals Effect of precise linker length, bond density, and broad temperature window on the rheological properties of ethylene vitrimers

Soft Matter ◽  
2021 ◽  
Author(s):  
Bhaskar Soman ◽  
Christopher M. Evans
Keyword(s):  
Relaxation Time ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Rheological Properties ◽  
Dynamic Networks ◽  
Arrhenius Behavior ◽  
Linker Length ◽  
Bond Density ◽  
Temperature Window

Dynamic networks with precise spacers between boronic ester bonds were investigated over a broad temperature window. Arrhenius behavior breaks down and an increase in relaxation time is observed when approach the glass transition temperature.

Molecular mobility around the glass transition temperature: a mini review

2004 ◽  
Vol 5 (2) ◽  
pp. 127-134 ◽  
Author(s):  
G. Roudaut ◽  
D. Simatos ◽  
D. Champion ◽  
E. Contreras-Lopez ◽  
M. Le Meste
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Molecular Mobility

scholarly journals Influence of the Polymer Glass Transition Temperature and Molecular Weight on Drug Amorphization Kinetics Using Ball Milling

Pharmaceutics ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 483 ◽  
Author(s):  
Camilla Asgreen ◽  
Matthias Manne Knopp ◽  
Jeppe Skytte ◽  
Korbinian Löbmann
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ball Milling ◽  
Molecular Mobility ◽  
Polymer Molecular Weight ◽  
Polymer Glass

In this study, the putative correlation between the molecular mobility of a polymer and the ball milling drug amorphization kinetics (i.e., time to reach full drug amorphization, ta) was studied using different grades of dextran (Dex) and polyvinylpyrrolidone (PVP) and the two model drugs indomethacin (IND) and chloramphenicol (CAP). In general, IND had lower ta values than CAP, indicating that IND amorphized faster than CAP in the presence of the polymers. In addition, an increase in polymer molecular weight (Mw) also led to an increase in ta for all systems investigated up to a critical Mw for each polymer, which was in line with an increase of the glass transition temperature (Tg) up to the critical Mw of each polymer. Hence, the increase in ta seemed to correlate well with the Tg/Mw of the polymers, which indicates that the polymers’ molecular mobility had an influence on the drug amorphization kinetics during ball milling.

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