Comment on ‘‘Scaling of the α relaxation in low-molecular-weight glass-forming liquids and polymers’’

1993 ◽  
Vol 71 (24) ◽  
pp. 4095-4095 ◽  
Author(s):  
Narayanan Menon ◽  
Sidney R. Nagel
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Glass Forming

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.

Density fluctuations around the glass-transition of low molecular weight glass-forming liquids

1991 ◽  
Vol 131-133 ◽  
pp. 134-138 ◽  
Author(s):  
E.W Fischer ◽  
G Meier ◽  
T Rabenau ◽  
A Patkowski ◽  
W Steffen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Density Fluctuations ◽  
Low Molecular Weight ◽  
Glass Forming

Positron annihilation study of a low-molecular-weight organic glass-forming liquid (BMMPC)

1999 ◽  
Vol 46 (6) ◽  
pp. 815-820 ◽  
Author(s):  
Sz Vass ◽  
A Patkowski ◽  
E. W Fischer ◽  
K Süvegh ◽  
A Vértes
Keyword(s):  
Molecular Weight ◽  
Positron Annihilation ◽  
Organic Glass ◽  
Low Molecular Weight ◽  
Glass Forming ◽  
Positron Annihilation Study
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