Thermodynamic investigation of glass transition in binary polyalcohols

Takeda, Kiyoshi; Murata, Katsuo; Yamashita, Shinsuke

doi:10.1016/s0022-3093(98)00538-9

Cited by 19 publications

(19 citation statements)

References 19 publications

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“…Takeda et al48 have studied the glass transition behavior of binary mixtures of several polyalcohols and polyamines. For all systems, the composition dependence of T g presented clear maxima, in strong contrast to those of polyalcohol‐polyalcohol mixtures reported previously 49. That was the reason they could not adjust these data to the empirical equation38,48 proposed for polyalcohol mixtures.…”

Section: Resultsmentioning

confidence: 57%

“…This transition has been not been observed for blends with high chitosan content, as shown in Figure 4. Ryabov et al49 have performed DSC measurements of anhydrous glycerol for the temperature interval from 133 to 303 K. They found the T g at 190 K and a quite distinguishable change in the sample heat capacity at 263 K. In a following publication, Ryabov et al53 explained this according to the mode‐coupling theory (MCT), which predicts a dynamic phase‐transition temperature from solid‐like to liquid‐like (amorphous) behavior at some critical temperature T c , which is located well above the T g. The dynamics of glass‐forming substances in supercooled and glassy states are usually characterized by several specific temperatures: the calorimetric glass‐transition temperature T g , the critical temperature T c of the idealized MCT,54 and the second scaling temperature T x introduced to collapse all the curves in a viscosity fragility plot to a single universal Vogel‐Fulcher‐Tammann dependence 55. Neutron and light scattering data of fragile liquids have been compared with MCT predictions with good agreement 56.…”

Section: Resultsmentioning

confidence: 99%

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Characteristic Features of Chitosan/Glycerol Blends Dynamics

Quijada‐Garrido

Laterza

Mazón-Arechederra

et al. 2006

Macro Chemistry & Physics

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Summary: The phase relaxation behavior of chitosan and its blends with glycerol has been studied by dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) techniques. The analysis of DMTA spectra of chitosan leads to recognition of two molecular relaxations in chitosan and its blends. The analysis of enthalpic and entropic contributions suggest that both processes involve a large degree of cooperativity. At high temperature, the α‐relaxation has been assigned to its glass transition temperature Tg on the basis of the stiffness of the chitosan backbone, the high activation energy, and the plasticization with glycerol. Tg may be originated by torsional oscillations between two glucopyranose rings across a β‐1,4‐glycosidic oxygen and a cooperative hydrogen bond reordering. The other is a low temperature β‐relaxation that, in chitosan, has been associated to motions of lateral pendant groups in the glucopyranose rings and in the blends to the movements of a glycerol hydrogel bonded to the lateral groups of chitosan. Its composition dependence has been modeled by means of the Schneider‐Riegel‐Penzel equation in which the interactions among functional groups when a glass‐forming liquid is adsorbed to a stiff, highly functionalized macromolecule such as chitosan are taken into account.A three‐dimensional plot representing the tan δ for a series of chitosan and chitosan/glycerol blends as a function of temperature and composition.magnified imageA three‐dimensional plot representing the tan δ for a series of chitosan and chitosan/glycerol blends as a function of temperature and composition.

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Characteristic Features of Chitosan/Glycerol Blends Dynamics

Quijada‐Garrido

Laterza

Mazón-Arechederra

et al. 2006

Macro Chemistry & Physics

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“…Glass formed during vitrification is known to undergo relaxation when stored at a temperature below its glass temperature, and this process will affect the preservation quality of biological materials The temperature in the holders was measured using a thermo recorder embedded in the glassy matrix [12]. Takeda et al [13] reported that differences in glass transition and (or) enthalpy relaxation depended on cryoprotectants, such as glycerol, propylene glycol, and EG. In the present study, the exposure times to the final vitrification solution were different between the DAP-top and E30S-top groups (5 min vs. 1 min); thus, dehydration may have been insufficient in the E30S-top group.…”

Section: Discussionmentioning

confidence: 99%

Vitrification of canine cumulus–oocyte complexes in DAP213 with a cryotop holder

Abe

Asano

Ali

et al. 2010

Reprod Medicine & Biology

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Purpose The effects of the cryoprotectant and the container (holder) used for the vitrification of canine germinal vesicle stage oocytes were examined to improve the cryopreservation method for canine oocytes and embryos. Methods Canine cumulus-oocyte complexes (COCs) were collected from ovaries, and were vitrified with E30S (30% ethylene glycol and 0.5 M sucrose) or DAP213 (2 M dimethyl sulfoxide, 1 M acetamide, and 3 M propylene glycol) solution held by a cryotube or cryotop sheets. After warming, the oocytes were stained with propidium iodide for the assessment of their plasma membrane integrity. Results In all the vitrification groups, more than 65% of the vitrified oocytes displayed a normal morphology (E30S-top, 65.6%; DAP-tube, 67.3%; DAP-top, 80.0%). However, when assessed by propidium iodide staining, the viability of oocytes in the DAP-top group (43.6%) was higher than that in the E30S-top group (21.3%, P \ 0.05). Furthermore, the viability of the oocytes in the DAP-top group (43.6%) was higher than that in the DAP-tube group (4.1%, P \ 0.05). Conclusions These results suggest that a combination of DAP213 as the cryoprotectant and a cryotop sheet as the holder improved viability after the vitrification of canine oocytes at the germinal vesicle stage.

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“…In clear contrast to equilibrium phenomena where the system sometimes exhibits thermodynamic anomalies due to infinite system size, the glass transition is less likely to exhibit anomalous behaviour. This is typically observed in the concentration dependence of glass transition temperature in solutions, in which the glass transition usually takes a monotonic curve form with little singularity [7].…”

Section: Introductionmentioning

confidence: 95%