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

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.

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.

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).

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Low-molecular-weight heparin in the prevention and treatment of thromboembolic disorders

1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Prevention And Treatment
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