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.

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.

Stability of low-molecular-weight polybutenes in thermooxidation and in exposure to an electric field

1986 ◽  
Vol 22 (8) ◽  
pp. 415-418
Author(s):  
V. V. Grigor'ev ◽  
K. V. Prokof'ev ◽  
G. V. Surovskaya ◽  
B. P. Belen'kii
Keyword(s):  
Molecular Weight ◽  
Electric Field ◽  
Low Molecular Weight

Electrorheological Effect in the Nematic and the Smectic A Phases of Low Molecular Weight Liquid Crystal

1999 ◽  
Vol 13 (14n16) ◽  
pp. 2005-2010 ◽  
Author(s):  
Keishi Negita
Keyword(s):  
Phase Transition ◽  
Molecular Weight ◽  
Liquid Crystal ◽  
Electric Field ◽  
Low Molecular Weight ◽  
Large Decrease ◽  
Smectic A ◽  
General Properties ◽  
Electrorheological Effect ◽  
Phase Sequence

Electrorheological (ER) effects in the nematic (Ne), the smectic A (SmA) and the isotropic (Is) phases of octyloxy cyanobiphenyl (8OCB) are studied. When an electric field is applied, a large decrease of the viscosity is observed in the Sm A phase, while in the Ne phase an increase of the viscosity is recognized with an anomalous ER effect near the SmA-Ne phase transition. These behaviors are suggested to be general properties of the liquid crystal exhibiting the phase sequence of SmA-Ne-Is.

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.

scholarly journals Reproductive and Behavioral Evaluation of a New Immunocastration Dog Vaccine

Animals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 226
Author(s):  
Daniela Siel ◽  
María José Ubilla ◽  
Sonia Vidal ◽  
Alexandra Loaiza ◽  
John Quiroga ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Recombinant Protein ◽  
Control Group ◽  
Low Molecular Weight ◽  
Specific Antibodies ◽  
Controlled Conditions ◽  
Low Molecular Weight Chitosan ◽  
And Control ◽  
Complementary Strategy ◽  
Positive Effect

Canine immunocastration development has been of interest for many years as a complementary strategy to surgical castration. The purpose of this paper was to verify the effect of a recombinant vaccine for dog immunocastration. Two tests were done, one under controlled conditions and a second under field conditions. Animals were injected with 1 mL of 500 µg GnRXG/Q recombinant protein; 500 µg of low molecular weight chitosan as adjuvant; 1 mL NaCl 0.9% q.s. In the first trial, eight Beagle male dogs between the ages of 1 and 3 comprised the sample, randomly divided into two groups: vaccinated group (n = 7) and control group (n = 2). The second trial had 32 dogs with owners. In the first controlled conditions trial, the vaccine produced specific antibodies that remained until the end of the trial (day 270), inducing reduced testosterone and spermiogram changes in the immunized animals. In a second trial, on the field, specific immunity was induced, which remained high up to day 150. The vaccine also reduced sexual agonistic and marking behaviors. This new vaccine proved to be safe, immunogenic, capable of reducing gonadal functionality, and had a positive effect on inducing reduced sexual, agonistic, and marking behavior of the animals.

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

Aggregation Structure and Electro—Optical Properties of (Liquid Crystalline Polymer)/(Low Molecular Weight Liquid Crystal) Composite System

1989 ◽  
Vol 171 ◽  
Author(s):  
Tisato Kajiyama ◽  
Hirotsugu Kikuchi ◽  
Akira Miyamoto ◽  
Satoru Moritomi ◽  
Jenn—Chiu Hwang
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Electric Field ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Smectic Phase ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Smectic Layer

ABSTRACTA series of thin films composed of liquid crystalline polymer (LCP) and low molecular weight liquid crystal (LMWLC) was prepared by a solventcasting method or by a bar—coating method. LCPs were of mesogenic side chain type with strong or weak polar terminalgroups in the side chain portion. A mixture of smectic LCP (LCP with side chain of strong polar end) and nematic LMWLC formed a smectic phase in a LCP weight fraction range above 50 %. Also, a mixture of nematic LCP (LCP with side chain of weak polar end) and nematic LMWLC with strong polar group induced a new smectic phase in a LCP molar fraction range of 20–80 %. Reversible and bistable electro-optical effects based on light scattering were recognized for a smectic phase of a binary composite composed of LCP and LMWLC. A light scattering state caused by many fragmented smectic lamellae appeared in the case of application of an a.c. electric field below a threshold frequency (∼l Hz). Furthermore, application of a 100 Vp—p a.c. field of 1 kHz made the transmission light intensity increased to 94 % within a few seconds. The optical heterogeneity in asmectic layer composed of the side chain group of LCP was caused by the difference of twoforces based on both dielectric anisotropy of the side chain and electrohydrodynamic motion of the main chain. Since application of a low frequency electric field causes an ioniccurrent throughout the mixture film, it is reasonable to consider that an induced turbulent flow of main chains by an ionic current collapsed a fairly well organized large smectic layer into many small fragments, resulting in an increase in light scattering. The response speed of LCP upon application of an electric field increased remarkably by mixingLMWLC. In the case of a smectic mesophase, turbid and transparent states remained unchanged as it was, even though after removing an electric field.1Such abistable and reversiblelight switching driven by two different frequencies of electric field could be newly realized by both characteristics of turbulent effect of a wellorganized large smectic layer of LCP and rapid response of LMWLC. We believe that the LCP/LMWLC mixture system is promissing as a novel type of “light valve” exhibiting memory effect (bistable light switching).

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