Density-mediated transport and the glass transition: high pressure viscosity measurements in the diamond anvil cell

Herbst, C. A.; Cook, Richard L.; King, H. E.

doi:10.1016/0022-3093(94)90445-6

Cited by 34 publications

(24 citation statements)

References 19 publications

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“…The cell is placed into a centrifuge and a centrifugal force is applied to accelerate the sphere. This way high pressure viscosities greater than 10 9 cP and up to 10 GPa pressures could be measured [35]. A centrifuge ball viscometer was developed for fluids, with a wide viscosity range of about 10 -1 to 10 5 Pas, which can operate over 400 o C [36].…”

Section: Magnetoviscometer: Mattischek and Sobczak Used A Magnetic VImentioning

confidence: 99%

“…The difficulty that limits to use of this equation is that one must know the γ, wall correction factor, prior to the measurements. They assumed that wall correction factor is independent of pressure, and stays constant throughout the experiments [1,34,35].…”

Section: Vibrating-wire Viscometersmentioning

confidence: 99%

“…Viscosity can be determined if the diffusion coefficient is measured for a probe particle of known size. Using light scattering method viscosities in the range of 10 -1 to 10 2 cP can be determined [35].…”

Section: Magnetoviscometer: Mattischek and Sobczak Used A Magnetic VImentioning

confidence: 99%

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High-Pressure Viscosity and Density of Polymer Solutions at the Critical Polymer Concentration in Near-Critical and Supercritical Fluids

Dindar

Kiran

2002

Ind. Eng. Chem. Res.

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The motivation for the determination of the viscosity of polymer solutions in dense fluids at the critical polymer concentration stems from the need to understand the factors that influence the time scale of phase separation in systems that undergo spinodal decomposition upon a pressure quench. In a recent investigation of PDMS + CO 2 and PE + n -pentane where molecular weights of the polymers and the critical polymer concentrations were comparable, significant differences were observed in the time evolution of new phase growth. Among the reasons that contribute to the difference in phase separation kinetics is the viscosity of the solutions. This thesis has been carried out to experimentally demonstrate the differences in viscosities of solutions at their critical polymer concentration. Specifically, the thesis focused on the high-pressure density and viscosity of solutions of poly(dimethylsiloxane) (M w = 93,700, M w /M n = 2.99) in supercritical carbon dioxide and of polyethylene (M w = 121,000, M w /M n = 4.3) in near-critical n -pentane. The measurements have been carried out a t the critical polymer concentrations, which is 5.5 wt % for solution of PDMS in CO 2 and 5.75 wt % for solution of PE in n -pentane. For PDMS + CO 2 system, the measurements were conducted at 55, 70, 85 and 100 o C and pressures up to 50 MPa. For iii PE + n-pentane system, the measurements were conducted at 140 and 150 o C and again up to 50 MPa. All measurements were conducted in the one-phase homogenous regions.At these temperatures and pressures, the viscosities were observed to be in the range from 0.14 mPa.s to 0.22 mPa.s for PDMS + CO 2 , and from 2.3 mPa.s to 4.6 mPa.s for PE + npentane systems. In both systems the viscosities increase with pressure and decrease with temperature. The temperature and pressure dependence could be described by Arrhenius type relationships in terms of flow activation energy (E # ) and flow activation volume (V # ) parameters. The flow activation energies in PDMS + CO 2 system were about 7 kJ/mol compared to about 18 kJ/mol for the PE + n -pentane system. The activation volumes were in the range 40-64 cm 3 /mol for PDMS + CO 2 system and 65-75 cm 3 /mol for the PE + n -pentane solution. The higher values of E # and V # represent the higher sensitivity of viscosity to temperature and pressure changes in the PE + n -pentane system. The viscosity d ata could also be correlated in terms of density using free-volume based Doolittle type equations. Density is shown to be an effective scaling parameter to describe T/P dependency of viscosity. The closed packed volumes suggested from density correlations were found to be around 0.33 cm 3 /g for the PDMS and 0.48 cm 3 /g for the PE systems. Comparison of the viscosity data in these systems with the data on the kinetics of pressure-induced phase separation confirms that the slower kinetics in the PE + n-pentane stems from the higher viscosity in this solution compared to the PDMS + CO 2 system, despite the similarity in the molecular weight of the polymer a...

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Section: Magnetoviscometer: Mattischek and Sobczak Used A Magnetic VImentioning

confidence: 99%

Section: Vibrating-wire Viscometersmentioning

confidence: 99%

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High-Pressure Viscosity and Density of Polymer Solutions at the Critical Polymer Concentration in Near-Critical and Supercritical Fluids

Dindar

Kiran

2002

Ind. Eng. Chem. Res.

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“…¿ÍÔÒÇÓËÏÇÐÕÂÎßÐÞÇ ËÔÔÎÇAEÑÄÂÐËâ ¿ÍÔÒÇÓËÏÇÐÕÂÎßÐÞÇ ËÔÔÎÇAEÑÄÂÐËâ ÄâÊÍÑÔÕË ÉËAEÍÑÔÕÇÌ ÒÓË ÄÞÔÑÍËØ AEÂÄÎÇÐËâØ ÒÓÑÄÑAEËÎËÔß, ÍÂÍ ÒÓÂÄËÎÑ, ÒÓË ÐÇÄÞÔÑÍËØ ÕÇÏÒÇÓÂÕÖÓÂØ (100 ë 400 K) Ô ËÔÒÑÎßÊÑÄÂÐËÇÏ ÏÇÕÑAEÑÄ ÒÂAEÂáÜÇÅÑ ÙËÎËÐAEÓÂ ËÎË ÛÂÓËÍÂ [12 ë 15], ÄËÃÓËÓÖáÜÇÅÑ ÍÓËÔÕÂÎÎÂ ËÎË ÔÕÓÖÐÞ [15,16], ÒÇÓÇÒÂAEÂ AEÂÄÎÇÐËâ Ä ÍÂÒËÎÎâÓÂØ [17,18] Ë AEÓ. £ ÒÑÔÎÇAEÐËÇ ÅÑAEÞ ÃÞÎ ÓÂÊÓÂÃÑÕÂÐ ÓâAE ÏÇÕÑAEËÍ ËÊÏÇÓÇÐËâ ÄâÊÍÑÔÕË ÉËAE-ÍÑÔÕÇÌ Ä ÂÎÏÂÊÐÞØ ÐÂÍÑÄÂÎßÐâØ, Ä ÕÑÏ ÚËÔÎÇ Ë AEÎâ ÑÚÇÐß ÄâÊÍËØ ÔÑÔÕÑâÐËÌ [19]. [24,25].…”

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“…ÇÄÇÓÐÞÇ ÑÙÇÐÍË ÔÎÂÃÑÅÑ ÓÑÔÕÂ ÄâÊÍÑÔÕË Ô AEÂÄÎÇÐËÇÏ AEÎâ ÉËAEÍÑÅÑ ÉÇÎÇÊÂ [23] ÔÄâÊÂÐÞ Ô ÐÇÑÒÓÂÄAEÂÐÐÑÌ àÍÔÕÓÂÒÑÎâÙËÇÌ àÏÒËÓËÚÇÔÍËØ ÔÑÑÕÐÑÛÇÐËÌ (3), (4) [19]. ³ÎÇAEÑÄÂÕÇÎßÐÑ, ÓÑÔÕ ÄâÊÍÑÔÕË ÓÂÔÒÎÂÄÂ Fe ÑÕ 10 4 À10 7 AEÑ ÖÓÑÄÐâ 10 11 ±a c ÏÑÉÇÕ ÒÓÑËÔØÑAEËÕß Ä AEÑÔÕÂÕÑÚÐÑ ÖÊÍÑÏ ËÐÕÇÓÄÂÎÇ AEÂÄÎÇÐËÌ Ë, ÔÑÑÕÄÇÕ-ÔÕÄÇÐÐÑ, ÅÎÖÃËÐ Ä âAEÓÇ.…”

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Universal viscosity growth in metallic melts at megabar pressures: the vitreous state of the Earth's inner core

Бражкин¹,

Lyapin²

2000

Uspekhi Fizicheskikh Nauk

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High‐pressure viscosity and density of polyethylene solutions in n‐pentane

Kiran

Gokmenoglu

1995

J of Applied Polymer Sci

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SYNOPSISViscosity and density of homogeneous one-phase solutions (1 wt %) of polyethylenes with narrow molecular weight distributions ( M , = 2150, 15,520, 108,000, and 420,000) in npentane were determined at 398,413, and 428 K over a pressure range from 20 to 60 MPa. Measurements were done with a special falling cylinder type viscometer that permits simultaneous determination of viscosity, density, and phase state of the solutions. It is shown that the viscosities of these solutions can be correlated with density ( p ) using the exponential relationships p = A exp {B/(1 -V,p)} or p = C1 exp (C,p), which are based on free-volume considerations. Analysis of the temperature dependence of viscosity at fixed pressures, and its pressure dependence a t fixed temperatures show that the flow-activation energies for these solutions are in the range 8-12 kJ/mol, and the apparent activation volumes are in the range 30-45 cm3/mol. Evaluation of the specific viscosity and analysis of the molecular weight dependence of intrinsic viscosity in accordance with Mark-Houwink type relationship p = KM" suggest a value of 0.5 for the exponent a, which is typical of poor or theta solvents.

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Density-mediated transport and the glass transition: high pressure viscosity measurements in the diamond anvil cell

Cited by 34 publications

References 19 publications

High-Pressure Viscosity and Density of Polymer Solutions at the Critical Polymer Concentration in Near-Critical and Supercritical Fluids

High-Pressure Viscosity and Density of Polymer Solutions at the Critical Polymer Concentration in Near-Critical and Supercritical Fluids

Universal viscosity growth in metallic melts at megabar pressures: the vitreous state of the Earth's inner core

High‐pressure viscosity and density of polyethylene solutions in n‐pentane

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