Viscoelastic properties of amorphous boron trioxide

Bernatz, K. M.; Echeverría, Isabel; Simon, Sindee L.; Plazek, D. J.

doi:10.1016/s0022-3093(01)00725-6

Cited by 13 publications

(5 citation statements)

References 35 publications

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“…where C 2 = T g − T ∞ and B = ln 10C 1 C 2 . 47,49 The WLF values are reported in Table 1, as well as the values for m and E g at the DSC T g . The fragility index m is a measure of glass-forming ability and is used to classify glass-forming liquids as strong or fragile, with fragile liquids having large m values.…”

Section: ■ Resultsmentioning

confidence: 99%

“…The VFT equation is equivalent to the Williams–Landel–Ferry (WLF) equation: where C 1 and C 2 are material constants and η ref is the viscosity at T g . The VFT and WLF parameters are related to one another and to the dynamic fragility m and the apparent activation energy E g at T g : , where C 2 = T g – T ∞ and B = ln 10 C 1 C 2 . , The WLF values are reported in Table , as well as the values for m and E g at the DSC T g . The fragility index m is a measure of glass-forming ability and is used to classify glass-forming liquids as strong or fragile, with fragile liquids having large m values .…”

Section: Resultsmentioning

confidence: 99%

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Rheology of Imidazolium-Based Ionic Liquids with Aromatic Functionality

Tao

Simon

2015

J. Phys. Chem. B

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A series of imidazolium-based ionic liquids with cyclic and aromatic groups and a bis[(trifluoromethane)sulfonyl]amide anion were characterized using dynamic and steady shear rheology in a wide temperature range. The cations investigated include 1-(cyclohexylmethyl)-3-methylimidazolium ([CyhmC1im](+)), 1-benzyl-3-methylimidazolium ([BnzC1im](+)), 1,3-dibenzylimidazolium ([(Bnz)2im](+)), and 1-(2-naphthylmethyl)-3-methylimidazolium ([NapmC1im](+)). Rheological properties are reported from terminal flow to the glassy state. All ionic liquids show very similar flow behavior with a glassy modulus approaching 1 GPa. The temperature dependences of the shift factors used for time-temperature superposition and the viscosity both follow the same VFT or WLF relationship, and the dynamic fragility at Tg ranges from 117 to 130 for the aromatic ionic liquids investigated, considerably more fragile, in the Angell sense, than the aliphatic analogs. Additionally, an anomalous aging effect in the dynamic viscosity response (i.e., a maximum observed at intermediate frequencies) was found using a strain-controlled rheometer but not using a stress-controlled rheometer.

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Section: ■ Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Rheology of Imidazolium-Based Ionic Liquids with Aromatic Functionality

Tao

Simon

2015

J. Phys. Chem. B

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“…The most stringent test for the model is supplied by the compliance measurements of Plazek and coworkers [29][30][31][32] , because these measurements separate retardation and viscosity explicitly. Fig.…”

Section: Comparison To Experimentsmentioning

confidence: 99%

“…In the case [29][30][31][32] . Notation see Table I (ARO is Aroclor # 1248 and OTP is orthoterphenyl).…”

Section: Comparison To Experimentsmentioning

confidence: 99%

On the mechanism of the highly viscous flow

Buchenau

2011

The Journal of Chemical Physics

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The asymmetry model for the highly viscous flow postulates thermally activated jumps from a practically undistorted ground state to strongly distorted, but stable structures, with a pronounced Eshelby backstress from the distorted surroundings. The viscosity is ascribed to those stable distorted structures which do not jump back, but relax by the relaxation of the surrounding viscoelastic matrix. It is shown that this mechanism implies a description in terms of the shear compliance, with a viscosity which can be calculated from the cutoff of the retardation spectrum. Consistency requires that this cutoff lies close to the Maxwell time. The improved asymmetry model compares well with experiment.

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“…Boron oxide properties and its composition are dependent on its water content. Therefore, because of its hygroscopic nature, precise care is needed for preparing and storing of boron oxide [11]. The production methods of boron oxide from boric acid in industrial scales, can be classified into two categories which are low temperature and high temperature productions.…”

Section: Introductionmentioning

confidence: 99%

The kinetics and mechanism of B2O3 formation from the chemically-synthesized HBO2 under non-isothermal conditions

Aghili

Panjepour

Meratian

2021

Reac Kinet Mech Cat

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In this investigation, a crystalline metaboric acid (HBO 2 ) powder was subjected to a dehydration process to transform it into boron oxide (B 2 O 3 ) using thermogravimetry (TG) technique in an argon atmosphere under non-isothermal conditions at different heating rates (3, 5, 10, and 15 °C min −1 ). The results of kinetic analysis revealed that the dehydration process was a complex one comprising a consecutive region (region I) followed by a parallel one (region II). Using the relevant kinetic models, the mechanisms involved in each region were analyzed by a proposed method for the complex reactions separately and find that the dehydration mechanism in the region I consisted of the kinetic models R 4 : g(α) = [1 − (1 − α) 2/3 ] (the chemical reaction at the HBO 2 /H 2 B 4 O 7 interface) and D 3 : g(α) = [1 − (1 − α) 1/3 ] 2 (the diffusion of H 2 O (g) in the H 2 B 4 O 7 layer), while that in the region II was parallel and consisted of the models D 3 (the diffusion of H 2 O (g) in the H 2 B 4 O 7 layer) and R 4 (the chemical reaction at the of H 2 B 4 O 7 /B 2 O 3 interface). Therefore, based on the kinetic results, the mechanisms of complex processes could be determined by the method.

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Viscoelastic properties of amorphous boron trioxide

Cited by 13 publications

References 35 publications

Rheology of Imidazolium-Based Ionic Liquids with Aromatic Functionality

Rheology of Imidazolium-Based Ionic Liquids with Aromatic Functionality

On the mechanism of the highly viscous flow

The kinetics and mechanism of B2O3 formation from the chemically-synthesized HBO2 under non-isothermal conditions

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