Measurement Analysis of Glass Transition Temperature for Sucrose and Trehalose Aqueous Solutions

2007 ◽  
Vol 36 (4) ◽  
pp. 1279-1285 ◽  
Author(s):  
G. A. Frank
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Aqueous Solutions ◽  
Measurement Analysis

Thermal Properties of PVP Cryoprotectants With Nanoparticles

2011 ◽  
Vol 2 (2) ◽  
Author(s):  
Baotong Hao ◽  
Baolin Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Aqueous Solutions ◽  
Specific Heat ◽  
Warming Rate ◽  
The Difference ◽  
Transfer Properties

Vitrification is an effective way for the cryopreservation of cells and tissues. The critical cooling rates for vitrification solution are relatively high. It is reported that nanoparticles can improve the heat transfer properties of solutions. To increase the heat transfer coefficient of aqueous cryoprotectant solutions, Hydroxyapatite (HA) nanoparticles were added into Polyvinylpyrrolidone (PVP) solutions (50%, 55%, and 60%, w/w). The glass-transition temperature, devitrification temperature, and specific heat of PVP aqueous solutions with/without HA nanoparticles (0.1%, 0.5%, and 1%, w/w) were measured by a differential scanning calorimeter at a cooling rate of 20°C/min and a warming rate of 10°C/min. The change in density of the above solutions with temperature was determined by using a straw that can reveal the volume change of solutions. The thermal conductivity was calculated based on the experimental data. A device that can be used to measure the thermal conductivity of vitrification solutions with/without nanoparticles was developed in this study. The results showed that the glass-transition temperature, devitrification temperature, and specific heat of PVP aqueous solutions with HA nanoparticles are larger than those without HA nanoparticles. The thermal conductivity of solutions with HA nanoparticles is larger than those without HA nanoparticles at a specific temperature. The lower the temperature, the smaller the difference in thermal conductivity between the solutions with and without HA nanoparticles. The calculated thermal conductivity meets the measured data well.

Thermal Properties of PVP Cryoprotectants With Nanoparticles

2009 ◽  
Author(s):  
Baotong Hao ◽  
Baolin Liu ◽  
Senjie Rong ◽  
Yan Zhou ◽  
Zhixin Gao
Keyword(s):  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Aqueous Solutions ◽  
Specific Heat ◽  
Warming Rate ◽  
Specific Temperature ◽  
The Difference ◽  
The Heat Transfer Coefficient

Vitrification is an effective way for the cryopreservation of cells and tissues. The critical cooling rates for vitrification solution are relatively high. It is reported that nanoparticles can improve the heat tranfer properties of solutions. To increase the heat transfer coefficient of aqueous cryoprotectant solutions, HA nanoparticles were added into PVP solutions (50%, 55%, 60%, w/w). The glass transition temperature, devitrification temperature and specific heat of PVP aqueous solutions with/without HA nanoparticles (0.1%, 0.5% and 1%, w/w) were measured by differential scanning calorimeter (DSC) at the cooling rate of 20°C/min and warming rate of 10°C/min. The change of density of above solutions with temperature was determined by using a straw that can reveal the volume change of solutions. The thermal conductivity was calculated based on the experimental data. A device that can be used to measure the thermal conductivity of vitrification solutions with/without nanoparticles was developed in this study. The results showed that the glass transition temperature, devitrification temperature and specific heat of PVP aqueous solutions with HA nanoparticles are larger than that without HA nanoparticles. The thermal conductivity of solutions with HA nanoparticles is larger than that without HA nanoparticles at a specific temperature. The lower the temperature, the smaller the difference of thermal conductivity between solutions with and without HA nanoparticles. The calculated thermal conductivity meets the measured data well.

scholarly journals Hydrogels Obtained via γ-Irradiation Based on Poly(Acrylic Acid) and Its Copolymers with 2-Hydroxyethyl Methacrylate

2020 ◽  
Vol 10 (14) ◽  
pp. 4960 ◽  
Author(s):  
Marin Micutz ◽  
Rodica Mihaela Lungu ◽  
Viorel Circu ◽  
Monica Ilis ◽  
Teodora Staicu
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Acrylic Acid ◽  
Aqueous Solutions ◽  
Functional Groups ◽  
Chemical Transformations ◽  
Hydroxyethyl Methacrylate ◽  
Γ Irradiation ◽  
Crosslinking Degree

Hydrogels containing both carboxyl and hydroxyl functional groups have been prepared by γ-irradiation of either aqueous solutions of acrylic acid (AA) and mixtures of AA and 2-hydroxyethyl methacrylate (HEMA) in different ratios, or aqueous solutions of poly(AA), PAA, and poly(AA-co-HEMA) obtained via solution polymerization. A higher absorbed dose is required in order to prepare hydrogels from monomer solutions, compared with those from polymer solutions. The range for the absorbed doses was chosen so that the probability of crosslinking reactions is higher than that of degradation ones. As the radiation energy deposited in a sample increases, the equilibrium swelling degree and the average molar mass between crosslinks diminishes. Chemical transformations induced by radiation were investigated by means of FTIR spectroscopy and thermal analysis of polymers before and after irradiation. For all these systems, the formation of a three-dimensional network enhances the glass transition temperature and thermal stability, but a further increase in the crosslinking degree may have the reverse effect on the glass transition temperature. Depending on the preparation protocol and/or hydrogel composition, superabsorbent materials that can bind different compounds throughout side functional groups may be obtained.

scholarly journals Synthesis, structure and properties of oligomeric ionic liquids of highly branched structure and special features of their self-arrangement

2021 ◽  
pp. 199-209
Author(s):  
Valery V. Shevchenko ◽  
◽  
Alexandr V. Stryutsky ◽  
Mariana A. Gumenna ◽  
Nina S. Klimenko ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ionic Conductivity ◽  
Nitrogen Atom ◽  
Aqueous Solutions ◽  
Alkyl Chain ◽  
Dilute Aqueous Solutions ◽  
Average Size

Synthesis, features of structural organization and behavior in aqueous solution of amphiphilic reactive aprotic cationic oligomeric ionic liquids obtained on the basis of a mixture of oligomeric amino- and hydroxyl-containing silsesquioxanes were considered. The dependence of the glass transition temperature, the value of ionic conductivity, self-organization in dilute aqueous solutions and the ζ-potential on the length of the alkyl substituent near the quaternary nitrogen atom in the composition of the synthesized compounds was shown. It was found that quaternization of the tertiary nitrogen atom of the starting oligomer causes a sharp decrease in the glass transition temperature. The value of the latter increases with an increase in the length of the hydrophobic alkyl fragments due to their association. In this case the ionic conductivity under anhydrous conditions decreases and at temperatures above 100°C drops by almost an order of magnitude. The maximum conductivity was reached for the oligomeric ionic liquid with the short alkyl chain and its value was 10-3 S/cm at 120oC. In dilute aqueous solutions the synthesized oligomeric ionic liquids with the short alkyl chain form aggregates with an average size of 100 nm while increasing the length of the alkyl chain prevents aggregation of silsesquioxane nuclei and leads to formation of unimolecular micelles with an average size of 3 nm

Sign in / Sign up

Export Citation Format

Share Document