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.

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.

Sorption of GR-S Type of Polymer on Carbon Black. III. Sorption by Commercial Blacks

1953 ◽  
Vol 26 (1) ◽  
pp. 102-114 ◽  
Author(s):  
I. M. Kolthoff ◽  
R. G. Gutmacher
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Intrinsic Viscosity ◽  
Benzene Solution ◽  
Weight Fraction ◽  
High Molecular Weight Fraction ◽  
Molecular Weights ◽  
Bound Rubber ◽  
Flow Through ◽  
Peculiar Behavior

Abstract The sorption capacities toward GR-S five commercial carbon blacks are in decreasing order: Spheron-6, Vulcan-1, Philblack-0, Sterling-105, Philblack-A. Apparently, the sorption is not related to surface area. The sorption on Vulcan-1 of GR-S from its solutions in seven different solvents or mixtures of solvents increases with decreasing solvent power for the rubber. The sorption curves of two “cold rubbers,” polymerized at −10 and +5° respectively, showed little difference from that of 50° GR-S. Previous heating of carbon black in nitrogen at 500 or 1100° increased the sorption by about 20 per cent over unheated carbon. Air-heating of carbon black at 425° did not cause a difference in the sorption from benzene solution, but produced an increase in the sorption of rubber from n-heptane solution. In the range 75% butadiene-25% styrene to 5% butadiene-95% styrene, there is practically no effect of the degree of unsaturation on the sorption. Polystyrene of high intrinsic viscosity exhibits a peculiar behavior with furnace blacks. Vulcan-1 sorbed microgel as well as the sol fraction from n-heptane solutions of GR-S containing microgel (conversion 74.7 and 81.5 per cent). There was no appreciable difference in the amount of sorption of rubber fractions having average molecular weights varying from 433,000 to 85,000. There is little change in the amount sorbed after two hours of shaking, but the intrinsic viscosity of the residual rubber decreases with time. The low molecular-weight rubber is sorbed more rapidly, but is slowly replaced by the more tightly sorbed high molecular weight fraction. Partial fractionation of a rubber sample can be achieved by allowing the rubber solution to flow through a column of weakly sorbing carbon black. A large portion of the sorbed rubber can be recovered from the column by washing it with a good solvent such as xylene. Bound rubber is produced by intimate mixing of equal parts of carbon black and rubber swollen in chloroform, when the mixture is dried in vacuum at 80° or at room temperature. Milling is not essential to get bound rubber.

Determination of Peroxides in Synthetic Rubbers

1945 ◽  
Vol 18 (4) ◽  
pp. 874-876
Author(s):  
Richard F. Robey ◽  
Herbert K. Wiese
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Quantitative Determination ◽  
High Molecular Weight ◽  
Active Oxygen ◽  
Lower Molecular Weight ◽  
Synthetic Rubber ◽  
High Molecular Weight Polymers ◽  
Methanol Solutions

Abstract Peroxides are found in synthetic rubbers either as the result of attack by oxygen, usually from the air, or as a residue from polymerization operations employing peroxide catalysts. Because of possible detrimental effects of active oxygen on the properties of the rubber, a method of quantitative determination is needed. The concentration of peroxides in substances of lower molecular weight may be determined with ferrous thiocyanate reagent, either titrimetrically as recommended by Yule and Wilson or colorimetrically as by Young, Vogt, and Nieuwland. Unfortunately, many highly polymeric substances are not soluble in the acetone and methanol solutions employed in these procedures. This is also the case with hydrocarbon monomers, such as butadiene, containing appreciable concentrations of soluble high molecular weight polymers. Bolland, Sundralingam, Sutton and Tristram recommended benzene as a solvent for natural rubber samples and the reagent made up in methanol. However, most synthetic rubbers are not readily soluble even in this combination. The following procedure employs the ferrous thiocyanate reagent in combination with a solvent capable of maintaining considerable concentrations of synthetic rubber in solution. The solvent comprises essentially 20 per cent ethanol in chloroform.

scholarly journals High Molecular Weight Factor VIII Coagulant Activity in Cryoprecipitate and Polyethylene Glycol Precipitates

1977 ◽  
Author(s):  
K. A. Rickard ◽  
T. Exner ◽  
H. Kronenberg
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Factor Viii ◽  
High Molecular Weight ◽  
Gel Filtration ◽  
Lower Molecular Weight ◽  
Human Antibody ◽  
High Molecular Weight Material ◽  
Coagulant Activity ◽  
Molecular Weight Form

Gel filtration of human plasma cryoprecipitate on Sepharose 2B indicated the molecular weight of factor VIII coagulant activity (VIIIc) to be significantly greater than that found in antihaemophilic concentrate. Polyethylene glycol at 3% concentration precipitated approximately half of the VIIIc from cryoprecipitate. This activity eluted as high molecular weight material on gel filtration. The addition of more polyethylene glycol to a concentration of 8% precipitated most of the remaining VIIIc from cryoprecipitate. This activity appeared to be of significantly lower molecular weight, approximately corresponding in elution volume to that observed for antihaemophilic concentrate. The possibility that an antibody to VIIIc generated in a patient treated with cryoprecipitate might be directed against the higher molecular weight form of factor VIII was investigated. However, no significant differences between the higher and lower molecular weight forms of factor VIII either in stability or in reactivity with human antibody to factor VIII were found.

Studies on Carbon Black. III. Theory of Bound Rubber

1957 ◽  
Vol 30 (1) ◽  
pp. 157-169
Author(s):  
D. S. Villars
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Selective Adsorption ◽  
General Sense ◽  
Polymer Molecules ◽  
Naturally Occurring ◽  
High Molecular Weight Material ◽  
Chemical Type ◽  
Bound Rubber ◽  
Set Up

Abstract Theories of reinforcement may be grouped into two general classes, mechanical and chemical. The mechanical type of theory attempts to explain reinforcement by alteration of direction of tear or by mechanieal entrainment. The chemical type of theory invokes the formation of bonds between the filler and rubber. Because of its implication with respect to the latter, Fielding of Goodyear developed a “bound rubber” test. The amount of rubber bound to carbon black was defined as that unextractable from the raw masterbatch by benzene. Some ten years ago, Baker and Walker reported an insolubilization of GR-S, on mixing with carbon black, over and above the amount of naturally occurring gel. The amount of insolubilized polymer increases with increasing molecular weight of the GR-S, and a selective adsorption of the high molecular weight material was found. Since this phenomenon was obtained also in polymers where they believed chemical gelation to be impossible, the conclusion was drawn by them that it is purely physical—this notwithstanding the fact that they found that extractions at higher temperatures failed to remove the insolubilized polymer. Because the method of analysis for insolubilized polymer used by Baker and Walker was essentially a bound-rubber analysis, interest in the latter was revived and it became desirable to set up a hypothesis to explain the mechanism of bound-rubber formation. (Let us understand the term “rubber” as applying in its more general sense as synonymous with “elastomer”.) The present paper reports a theory developed by the writer about ten years ago to explain various observations on the hypothesis that bound rubber is a gel of carbon black particles, the bonding agent of which consists of the longer polymer molecules. The theory interprets the observed linear dependence of bound rubber on loading in terms of an elemental area associated with the segmental adsorption of elastomer molecules, the molecular weight of these segments, and the functionality of the carbon black particles.

Molecular Weight Effects in Adsorption of Rubbers on Carbon Black

1968 ◽  
Vol 41 (5) ◽  
pp. 1256-1270 ◽  
Author(s):  
Gerard Kraus ◽  
J. T. Gruver
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Large Particle ◽  
Molecular Weights ◽  
Molecular Weight Dependence ◽  
Bound Rubber ◽  
Sieve Effect ◽  
High Structure ◽  
Very High ◽  
Poor Solvent

Abstract The molecular weight dependence of the adsorption of polybutadiene on carbon black from a poor solvent, n-heptane, and bulk, i.e., the phenomenon of “bound rubber”, was investigated. For narrow distribution polymers the adsorption is proportional to Mn, where n = 0.14 for adsorption from n-heptane solution; n = 0.5 for adsorption from bulk. Anomalously low solution adsorption was observed for polymers of very high molecular weight (> 500,000). This is ascribed to a sieve effect by aggregates of carbon black particles which cannot be penetrated by the large molecular coils. In high structure blacks, which pack more loosely, and in large particle blacks, which form larger interstices between particles, onset of anomalous adsorption is shifted toward higher molecular weights.

The Inhibition by Plasma of Urokinase and Tissue Activator-Induced Fibrinolysis in Pregnancy and the Puerperium

1983 ◽  
Vol 49 (01) ◽  
pp. 021-023 ◽  
Author(s):  
J E Walker ◽  
L Gow ◽  
D M Campbell ◽  
D Ogston
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Inhibitory Activity ◽  
Lower Molecular Weight ◽  
Amidolytic Activity ◽  
Third Trimester ◽  
The Third ◽  
Molecular Weight Fractions ◽  
In Pregnancy

SummaryThe activity of urokinase and tissue activator on fibrin plates was inhibited by plasma from women in the third trimester of pregnancy to a greater extent than by non-pregnant plasma. Pregnancy also inhibited the amidolytic activity of urokinase. The high molecular weight fractions of pregnancy plasma gel filtered on Sephadex G-200 showed comparable inhibitory activity against urokinase as fractions for non-pregnant plasma; in contrast with non-pregnant plasma, the lower molecular weight fractions of pregnancy plasma were markedly inhibitory against urokinase. Plasma exposed to lysine-Sepharose to remove plasminogen and then fractionated on Sephadex G-100 provided a pattern of three areas of inhibition against tissue activator similar to that seen in non-pregnant plasma. The urokinase-inhibitory activity of lower molecular weight fractions of plasma separated on Sephadex G-200 fell within 1 hr of delivery and fell further over the following 18 to 30 hr.

Rheomacrodex

1964 ◽  
Vol 2 (6) ◽  
pp. 24-24
Keyword(s):  
Molecular Weight ◽  
Blood Vessels ◽  
High Molecular Weight ◽  
Plasma Volume ◽  
Tissue Damage ◽  
Sucrose Solution ◽  
Red Cells ◽  
Lower Molecular Weight ◽  
Low Molecular Weight

Dextrans are chain polymers of glucose of high molecular weight, which are produced when certain bacteria are incubated with sucrose solution. Solutions of dextrans of high or low molecular weight may be extracted. Dextrans of high molecular weight (75,000 – 200,000) are used as plasma volume expanders (e. g. Intradex - Glaxo; Dextraven - Benger), and dextrans of lower molecular weight (40,000) are claimed to be useful in improving flow by preventing any tendency that red cells have to clump and block small blood vessels (Rheomacrodex - Pharmacia). Such clumping of red cells may occur after tissue damage; it is sometimes called sludging of blood.

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