Scaling of high-pressure viscosity data in low-molecular-weight glass-forming liquids

1999 ◽  
Vol 60 (5) ◽  
pp. 2979-2982 ◽  
Author(s):  
M. Paluch ◽  
Z. Dendzik ◽  
S. J. Rzoska
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Low Molecular Weight ◽  
Viscosity Data ◽  
Glass Forming

High pressure aging studies on the low-molecular weight glass-forming pharmaceutical – Probucol

2021 ◽  
Vol 321 ◽  
pp. 114626
Author(s):  
Aldona Minecka ◽  
Barbara Hachuła ◽  
Karolina Jurkiewicz ◽  
Kamil Kamiński ◽  
Marian Paluch ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Low Molecular Weight ◽  
Glass Forming ◽  
Aging Studies

Molecular Weight Determinations Of Low Molecular Weight (LMW) Heparins By Ultracentrifugation And High Pressure Liquid Chromatography

1981 ◽  
Author(s):  
Grant Barlow ◽  
N Sugisaka ◽  
F J Petracek
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Low Molecular Weight ◽  
Analytical Ultracentrifuge ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Heparin Fractions

Molecular weights were independently determined on nitrous acid depolymerized LMW heparin fractions ranging from 2-15 daltons using the analytical ultracentrifuge and high pressure liquid chromatography (HPLC).Sedimentation-diffusion equilibria were obtained in the analytical ultracentrifuge using speeds ranging from 20,000 to 56,000 rpm. Near theta conditions were obtained using 0.5M NaCl as the solvent. Calculations of molecular weight distributions and, from those figures, weight average molecular weights were made using the method described by Scholte (N.Y. Acad Sci. 164, 156, 1969). The results show that weight average values as low as 2,000 daltons can be determined.Sedimentation-diffusion equilibria were obtained in the analytical ultracentrifuge using speeds ranging from 20,000 to 56,000 rpm. Near theta conditions were obtained using 0.5M NaCl as the solvent. Calculations of molecular weight distributions and, from those figures, weight average molecular weights were made using the method described by Scholte (N.Y. Acad Sci. 164, 156, 1969). The results show that weight average values as low as 2,000 daltons can be determined.The HPLC results were obtained using previously described methods (Fed Proc. 36, 89, 1977) and a new highly efficient gel column (TSK gels). Fractionated dextrans were used as reference standards.

scholarly journals Activation volume in superpressed glass-formers

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Aleksandra Drozd-Rzoska
Keyword(s):  
Molecular Weight ◽  
Relaxation Time ◽  
Absolute Stability ◽  
Activation Volume ◽  
Stability Limit ◽  
Low Molecular Weight ◽  
Glass Forming ◽  
Deep Earth ◽  
Structural Relaxation Time ◽  
The Given

Abstract In pressurized glass-forming systems, the apparent (changeable) activation volume Va(P) is the key property governing the previtreous behavior of the structural relaxation time (τ) or viscosity (η), following the Super-Barus behavior: $${\boldsymbol{\tau }}{\boldsymbol{(}}{\boldsymbol{P}}{\boldsymbol{)}}{\boldsymbol{,}}{\boldsymbol{\eta }}{\boldsymbol{(}}{\boldsymbol{P}}{\boldsymbol{)}}{\boldsymbol{\propto }}{\bf{\exp }}{\boldsymbol{(}}{{\boldsymbol{V}}}_{{\boldsymbol{a}}}{\boldsymbol{(}}{\boldsymbol{P}}{\boldsymbol{)}}{\boldsymbol{/}}{\boldsymbol{R}}{\boldsymbol{T}}{\boldsymbol{)}}$$ τ ( P ) , η ( P ) ∝ exp ( V a ( P ) / R T ) , T = const. It is usually assumed that Va(P) = V#(P), where $${{\boldsymbol{V}}}^{{\boldsymbol{\#}}}{\boldsymbol{(}}{\boldsymbol{P}}{\boldsymbol{)}}={\boldsymbol{R}}{\boldsymbol{T}}{\boldsymbol{d}}\,{\boldsymbol{ln}}\,{\boldsymbol{\tau }}{\boldsymbol{(}}{\boldsymbol{P}}{\boldsymbol{)}}{\boldsymbol{/}}{\boldsymbol{d}}{\boldsymbol{P}}$$ V # ( P ) = R T d ln τ ( P ) / d P or $${{\boldsymbol{V}}}^{{\boldsymbol{\#}}}{\boldsymbol{(}}{\boldsymbol{P}}{\boldsymbol{)}}{\boldsymbol{=}}{\boldsymbol{R}}{\boldsymbol{T}}{\boldsymbol{d}}\,{\boldsymbol{ln}}\,{\boldsymbol{\eta }}{\boldsymbol{(}}{\boldsymbol{P}}{\boldsymbol{)}}{\boldsymbol{/}}{\boldsymbol{d}}{\boldsymbol{P}}$$ V # ( P ) = R T d ln η ( P ) / d P . This report shows that Va(P) ≪ V#(P) for P → Pg, where Pg denotes the glass pressure, and the magnitude V#(P) is coupled to the pressure steepness index (the apparent fragility). V#(P) and Va(P) coincides only for the basic Barus dynamics, where Va(P) = Va = const in the given pressure domain, or for P → 0. The simple and non-biased way of determining Va(P) and the relation for its parameterization are proposed. The derived relation resembles Murnaghan - O’Connel equation, applied in deep Earth studies. It also offers a possibility of estimating the pressure and volume at the absolute stability limit. The application of the methodology is shown for diisobutyl phthalate (DIIP, low-molecular-weight liquid), isooctyloxycyanobiphenyl (8*OCB, liquid crystal) and bisphenol A/epichlorohydrin (EPON 828, epoxy resin), respectively.

Formation of new polymorphs and control of crystallization in molecular glass-formers by electric field

2018 ◽  
Vol 20 (2) ◽  
pp. 925-931 ◽  
Author(s):  
K. Adrjanowicz ◽  
M. Paluch ◽  
R. Richert
Keyword(s):  
Molecular Weight ◽  
Electric Field ◽  
Low Molecular Weight ◽  
Glass Forming ◽  
Molecular Glass ◽  
And Control ◽  
Crystallization Tendency

We show that an electric field is able to modify the crystallization tendency of a low-molecular weight glass-forming liquid.

Glass formation from low molecular weight organic melts

1995 ◽  
Vol 10 (8) ◽  
pp. 2128-2136 ◽  
Author(s):  
Seong-Jin Kim ◽  
T.E. Karis
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Hydrogen Bonding ◽  
Glass Formation ◽  
Glass Forming Ability ◽  
Rotational Isomerism ◽  
Molecular Structures ◽  
Low Molecular Weight ◽  
Glass Forming ◽  
Temperature Crystallization

Glass formation from the melt of organic monomers was studied for a variety of different organic molecular structures with Tg near ambient temperature. Crystallization is suppressed by one or more of the molecular properties, hydrogen bonding, interlocking, dipolar, and hydrogen bonding, combined with hindered rotational isomerism. Examples of materials in each category are presented for illustration. The viscosity of undercooled liquids was characterized by the Vogel-Tammon-Fulcher (VTF) equation, η = A cxp[DT0/(T - T0)], where A, D, and T0 are experimentally determined parameters. Our experimental D values are discussed in relation to the molecular structure and glass formation mechanism. The insight provided by our interpretation is intended to assist in the design of new molecular structures with controlled viscosity-temperature characteristics, as well as glass-forming ability by cooling from melts.

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