Nature of the Cohesional Strength of Synthetic Cis-Polyisoprene SKI-3 and Carbon Black Compounds Based on It

1973 ◽  
Vol 46 (5) ◽  
pp. 1234-1238 ◽  
Author(s):  
V. A. Grechanovskii ◽  
L. S. Ivanova ◽  
I. Ya Poddubnyi
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
High Molecular Weight ◽  
Chain Segment ◽  
Segment Orientation

Abstract SKI-3 gum rubbers containing tight gel have high cohesional strength (up to 12 kg/cm2) at the same time that sol fractions of these rubbers and also of NR have low cohesional strength (˜2 kg/cm2). The loss by black compounds based on SKI-3 of cohesional strength is explained by the breakdown during milling of networks of physical entanglements existing in these rubbers. For the production of carbon black compounds based on crystallizing elastomers with high cohesional strength, the presence of sufficiently stable networks able to insure the initial chain segment orientation during extension and a high molecular weight of the macromolecule are necessary.

Mixing of Carbon Black with Rubber. VI. Analysis of NR/SBR Blends

1988 ◽  
Vol 61 (4) ◽  
pp. 609-618 ◽  
Author(s):  
George R. Cotten ◽  
Lawrence J. Murphy
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
High Molecular Weight ◽  
Surface Area ◽  
Bound Rubber ◽  
Very High

Abstract The distribution of carbon black in NR/SBR blends was determined through the analysis of bound rubber. The NR/SBR blends were found to be very different from the previously studied SBR/BR compounds: these differences were assigned to mutual insolubility of the two polymers and a very high molecular weight of NR. In NR/SBR blends, it was found that changes in molecular weight of the polymer has no effect on the carbon black distribution in the blend. While the “activity” of carbon black did not affect the distribution, the loading of the black in NR decreased linearly with increasing surface area of the black. Approximately 35% of normal tread blacks (surface area 80–100 m2/g) was found in the NR phase. However, the bond between NR and carbon black is quite weak, and black continues to migrate into the SBR phase on prolonged mixing or during blending of NR and SBR masterbatches.

An HF-Nickel-R3Al Catalyst System for Producing High Cis-1,4-Polybutadiene

1972 ◽  
Vol 45 (1) ◽  
pp. 268-277 ◽  
Author(s):  
M. C. Throckmorton ◽  
F. S. Farson
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
High Molecular Weight ◽  
Catalyst Concentration ◽  
Dynamic Properties ◽  
Catalyst System ◽  
Polymerization Temperature

Abstract A relatively new, high cis-1,4-polybutadiene and a novel trialkylaluminumnickel-HF catalyst system have been described. This polybutadiene is unique in that it possesses high tack and has exceptionally good processing qualities; the carbon black-loaded and cured rubber possesses good static and dynamic properties. The catalyst system is very effective for producing high molecular weight rubber, suitable for oil extension, and the molecular weight can be controlled by adjusting 1) HF to R3Al ratio, 2) total catalyst concentration and/or 3) polymerization temperature.

Formation of Bound Rubber of GR-S Type Polymers with Carbon Blacks

1952 ◽  
Vol 25 (3) ◽  
pp. 500-516 ◽  
Author(s):  
June Duke ◽  
W. K. Taft ◽  
I. M. Kolthoff
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
High Molecular Weight ◽  
Lower Molecular Weight ◽  
Carbon Blacks ◽  
Bound Rubber ◽  
Temperature Levels ◽  
Black Other ◽  
Lower Carbon

Abstract The bound rubber-black complex formed by milling various GR-S polymers and carbon blacks at several temperature levels was studied. The amount of bound polymer increased with greater loadings of black, but per unit of carbon black, it decreased at the higher black loadings. The temperature of mixing likewise has a large effect—at lower carbon black loadings, higher temperatures increase the amount of binding; the effect ia minimized as the loading is increased until at high loadings (100 to 125 parts of black per 100 parts of rubber) this effect is eliminated. By fractionation of the sol portion, it has been shown that polymer of progressively lower molecular weight is bound as the black loading is increased. Polymer of high molecular weight does not replace bound polymer of lower molecular weight; the polymer of higher molecular weight is preferentially bound during mill mixing. Although more polymer appears to be bound as the conversion is increased from 50 to 72 per cent at a loading of 50 parts of black, other factors besides conversion may be determinative. No differences in relationship were found for polymers made at 122° or 41° F.

Microtubule motors and other maps

1990 ◽  
Vol 48 (3) ◽  
pp. 1-1
Author(s):  
Richard B. Vallee
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Structural Components ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
Associated Proteins ◽  
The Subject ◽  
Intracellular Motility

Microtubules are involved in a number of forms of intracellular motility, including mitosis and bidirectional organelle transport. Purified microtubules from brain and other sources contain tubulin and a diversity of microtubule associated proteins (MAPs). Some of the high molecular weight MAPs - MAP 1A, 1B, 2A, and 2B - are long, fibrous molecules that serve as structural components of the cytamatrix. Three MAPs have recently been identified that show microtubule activated ATPase activity and produce force in association with microtubules. These proteins - kinesin, cytoplasmic dynein, and dynamin - are referred to as cytoplasmic motors. The latter two will be the subject of this talk.Cytoplasmic dynein was first identified as one of the high molecular weight brain MAPs, MAP 1C. It was determined to be structurally equivalent to ciliary and flagellar dynein, and to produce force toward the minus ends of microtubules, opposite to kinesin.

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