scholarly journals Silane-modified low molecular weight ‘liquid’ polymers in sulfur cured mixtures of styrene-butadiene copolymers and silica

2021 ◽  
Vol 93 ◽  
pp. 106997
Author(s):  
M. Gruendken ◽  
M.M. Velencoso ◽  
D. Koda ◽  
A. Blume
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Liquid Polymers ◽  
Styrene Butadiene

Low-molecular-weight styrene–butadiene copolymers (L-SSBR) as processing aids used for silica-filled rubber: Synthesis, functionalization and application

2018 ◽  
Vol 51 (3) ◽  
pp. 244-261
Author(s):  
Barbara Robak ◽  
Jarosław Rogoża ◽  
Mieczysław Łapkowski
Keyword(s):  
Molecular Weight ◽  
Functional Groups ◽  
Gel Permeation Chromatography ◽  
Proton Nuclear Magnetic Resonance ◽  
Low Molecular Weight ◽  
Nuclear Magnetic Resonance Analysis ◽  
Resonance Analysis ◽  
Filled Rubber ◽  
Cure Characteristic ◽  
Styrene Butadiene

Three different types of low-molecular-weight solution styrene-butadiene rubbers (L-SSBRs) were synthesized by anionic polymerization. Two of them were end-capped with methoxy (M-L-SSBR) and ethoxy (E-L-SSBR) functional groups, respectively, while the other was terminated with alcohol (L-SSBR). The content of functional groups was estimated on the basis of gel permeation chromatography and proton nuclear magnetic resonance analysis. The influence of L-SSBR on the properties of silica-filled SSBR as an alternative for the plasticizing oil was investigated in tyre tread formulation. L-SSBRs of high vinyl content were used in place of part of oil for preparation of compound K1 enriched with linear (L-SSBR) and compound K2 and K3 enriched with two star-like liquid rubbers modified, respectively, with methoxy (M-L-SSBR) and ethoxy (E-L-SSBR) functional groups. Although particular attention was paid to the effect of polar groups on the silica dispersions, cure characteristic, compound viscosity and mechanical properties were also analyzed. Rubber with only treated distillate aromatic extract was used (K5) as the reference.

Unusually high values of the quotient d ln η/d ln M of some low-molecular-weight liquid polymers

1985 ◽  
Vol 50 (11) ◽  
pp. 2570-2578
Author(s):  
Miloslav Bohdanecký ◽  
Alois Kaštánek ◽  
František Lešek
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
Low Molecular Weight ◽  
Atomic Group ◽  
Polymeric Liquids ◽  
Random Coils ◽  
Chain Atom ◽  
Flow Processes ◽  
Liquid Polymers ◽  
Main Chain Atom

Unusually high values of the quotient d ln η/d ln M ≡ a (where η is viscosity and M is molecular weight) found for some low-molecular-weight liquid polymers (4 ⪬ a ⪬ 8) are discussed in terms of the theory of flow processes of polymeric liquids. The effect is assigned mainly to the dependence on the chain length of the friction factor per main chain atom or atomic group but deviations of short chains from the conformation of random coils can also contribute significantly. The variation of the quotient a with temperature, however, is due to the former factor only.

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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