Sedimentation Analysis of Styrene Butadiene Copolymer Rubber

1966 ◽  
Vol 39 (3) ◽  
pp. 622-630
Author(s):  
Terutake Homma ◽  
Hiroshi Fujita
Keyword(s):  
Molecular Weight ◽  
Distribution Function ◽  
Mass Distribution ◽  
Sedimentation Coefficient ◽  
Distribution Functions ◽  
Sedimentation Analysis ◽  
Molecular Weights ◽  
Integral Distribution ◽  
Styrene Butadiene ◽  
Theta Solvent

Abstract Methods are presented by which the limiting viscosity number [η]Θ and the limiting sedimentation coefficient s0 of a monodisperse linear polymer in its theta solvent as functions of the molecular weight M may be deduced from data taken with a series of polydisperse samples of the polymer. The necessary data are the limiting viscosity numbers and the distribution functions of s0 of the chosen samples in the theta solvent, plus their number-average molecular weights. The methods are applied to unfractionated and fractionated samples of a styrene-butadiene co-polymer rubber (SBR) having 24 weight per cent bound styrene in a theta solvent, 2-pentanone, at 21.0° C. The following relations are deduced for monodisperse unbranched SBR in this theta solvent: [η]Θ=1.73×10−3M21 and s0=0.83×10−15M21, where [η]Θ is expressed in deciliters/gram and s0 in seconds. Besides these, the viscosity—molecular weight relations for this cold rubber in toluene and in cyclohexane, both at 30° C, are established. The new relation for the toluene system does not accord with the French-Ewart relation for “hot” rubber in the same solvent. The integral distribution of molecular weight in an unfractionated SBR is calculated from its distribution function of s0 in 2-pentanone at 21.0° C by using the derived s0 versus M relationship, and is found to coincide well with the mass distribution obtained from fractionation data if the new viscosity—molecular weight relation is used for the molecular weight of each fraction.

An Investigation of the Molecular Weight Distribution of Polymers with the Aid of the Ultracentrifuge

1957 ◽  
Vol 30 (2) ◽  
pp. 487-506
Author(s):  
S. E. Bresler ◽  
S. Y. Frenkel
Keyword(s):  
Molecular Weight ◽  
Distribution Function ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Functional Relation ◽  
Distribution Functions ◽  
Linear Polymers ◽  
Molecular Weights ◽  
Direct Experiment ◽  
And Diffusion

Abstract In the present paper a method for studying the molecular weight distribution of linear polymers, involving the following stages, is developed: 1. Fractionation of the polymer into a series of sufficiently narrow fractions and investigation of these fractions with the aid of the ultracentrifuge and diffusion. 2. Plotting the distribution functions of sedimentation constants for each fraction and subsequent summation of curves in order to build up the distribution function of the sedimentation constants for the whole polymer. 3. Discovery of a general functional relation between the sedimentation constants and molecular weights for a given series of polymer homologs and construction of the distribution function of molecular weights of the polymer. The basis of the method developed by us (method of equivalent Gaussian distributions) was confirmed by direct experiment. Application of this method of investigation to a number of industrial polymers will be described in the next paper.

scholarly journals Molecular weights of the Thy-1 glycoproteins from rat thymus and brain in the presence and absence of deoxycholate

1978 ◽  
Vol 169 (2) ◽  
pp. 411-417 ◽  
Author(s):  
P W Kuchel ◽  
D G Campbell ◽  
A N Barclay ◽  
A F Williams
Keyword(s):  
Molecular Weight ◽  
Equilibrium Dialysis ◽  
Sedimentation Coefficient ◽  
Sedimentation Equilibrium ◽  
Membrane Glycoproteins ◽  
Guanidinium Chloride ◽  
Molecular Weights ◽  
Methionine Residue ◽  
Disulphide Bonds ◽  
Binding Data

1. The Thy-1 membrane glycoproteins from rat thymus and brain bound deoxycholate to 24% of their own weight as measured by equilibrium dialysis. The binding occurred co-operatively at the critical micelle concentration of deoxycholate, suggesting that the glycoproteins bind to a micelle, and not to the detergent monomer. 2. From sedimentation-equilibrium and deoxycholate-binding data the molecular weights of the glycoprotein monomers were calculated to be 18700 and 17500 for thymus and brain Thy-1 glycoprotein monomers were calculated to be 18700 and 17500 for thymus and brain Thy-1 glycoproteins respectively. The molecular weight of the polypeptide part of the glycoprotein is thus 12500. 3. In the absence of deoxycholate, brain or thymus Thy-1 glycoprotein formed large homogeneous complexes of mol. wt. 270000 or 300000 respectively. The sedimentation coefficient of these was 12.8 S. The complex was only partially dissociated by 4M-guanidinium chloride. 4. After cleavage of brain or thymus Thy-1 glycoprotein with CNBr, two peptides were clearly identified. They were linked by disulphide bonds and both contained carbohydrate. This cleavage suggests there is only one methionine residue per molecule, which is consistent with the above molecular weights and the known amino acid composition.

scholarly journals A new general method for the assessment of the molecular-weight distribution of polydisperse preparations. Its application to an intestinal epithelial glycoprotein and two dextran samples, and comparison with a monodisperse glycoprotein

1973 ◽  
Vol 135 (4) ◽  
pp. 649-653 ◽  
Author(s):  
Richard A. Gibbons ◽  
Stephen N. Dixon ◽  
David H. Pocock
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Continuous Distribution ◽  
Distribution Functions ◽  
Intestinal Epithelial ◽  
Cysticercus Tenuicollis ◽  
Molecular Weights ◽  
Two Samples ◽  
General Method

A specimen of intestinal glycoprotein isolated from the pig and two samples of dextran, all of which are polydisperse (that is, the preparations may be regarded as consisting of a continuous distribution of molecular weights), have been examined in the ultracentrifuge under meniscus-depletion conditions at equilibrium. They are compared with each other and with a glycoprotein from Cysticercus tenuicollis cyst fluid which is almost monodisperse. The quantity c−⅓(c=concentration) is plotted against ξ (the reduced radius); this plot is linear when the molecular-weight distribution approximates to the ‘most probable’, i.e. when Mn:Mw:Mz: M(z+1)....... is as 1:2:3:4: etc. The use of this plot, and related procedures, to evaluate qualitatively and semi-quantitatively molecular-weight distribution functions where they can be realistically approximated to Schulz distributions is discussed. The theoretical basis is given in an Appendix.

scholarly journals An Efficient Procedure for Purification of an Isolate of Peanut Mottle Virus from Wild Peanut and Determination of Molecular Weights of the Viral Components1

1984 ◽  
Vol 11 (1) ◽  
pp. 40-42 ◽  
Author(s):  
John L. Sherwood
Keyword(s):  
Molecular Weight ◽  
Phosphate Buffer ◽  
Gradient Centrifugation ◽  
Potassium Phosphate ◽  
Sedimentation Coefficient ◽  
Infected Tissue ◽  
Mottle Virus ◽  
Efficient Procedure ◽  
Molecular Weights ◽  
Wild Peanut

Abstract An efficient procedure was developed for purification of peanut mottle virus (PMV) from pea (Pisum sativum cv. Little Marvel) that yielded 10–19 mg virus/ kg infected tissue. Virus was extracted from frozen infected tissue in 0.01 M potassium phosphate buffer, pH 8.0, with 0.001 M dithioerythritol, followed by clarification with chloroform (15%, v/v) and precipitation by KCl and polyethylene glycol. Virus was resuspended in 0.01 M borate-phosphate buffer, pH 8.3, with 0.2 M urea prior to density gradient centrifugation. Purified virus sedimented as a single component with a sedimentation coefficient of 149 S. The molecular weight of the single coat protein was estimated as 36,100 daltons in 12% polyacrylamide gels. The single nucleic acid isolated from PMV on sucrose gradients was degraded by RNase, but not DNase. The molecular weight of the RNA was estimated as 3.1 × 106 daltons on nondenaturing and denaturing sucrose gradients.

scholarly journals Two-integral distribution functions for axisymmetric galaxies

1993 ◽  
Vol 153 ◽  
pp. 357-358
Author(s):  
C. Hunter ◽  
E. Qian
Keyword(s):  
Distribution Function ◽  
Angular Momentum ◽  
Stellar System ◽  
Distribution Functions ◽  
New Method ◽  
Integral Distribution ◽  
Axis Of Symmetry

We present a new method for finding a distribution function f, which depends only on the two classical integrals of energy E and angular momentum J about the axis of symmetry, for a stellar system with a known axisymmetric potential and density.

scholarly journals Measures of concordance determined byD4-invariant copulas

2004 ◽  
Vol 2004 (70) ◽  
pp. 3867-3875 ◽  
Author(s):  
H. H. Edwards ◽  
P. Mikusiński ◽  
M. D. Taylor
Keyword(s):  
Distribution Function ◽  
Mass Distribution ◽  
Random Vector ◽  
Joint Distribution ◽  
Distribution Functions ◽  
Joint Distribution Function ◽  
Unit Square ◽  
Special Cases ◽  
Measures Of Concordance ◽  
Measure Of Association

A continuous random vector(X,Y)uniquely determines a copulaC:[0,1]2→[0,1]such that when the distribution functions ofXandYare properly composed intoC, the joint distribution function of(X,Y)results. A copula is said to beD4-invariant if its mass distribution is invariant with respect to the symmetries of the unit square. AD4-invariant copula leads naturally to a family of measures of concordance having a particular form, and all copulas generating this family areD4-invariant. The construction examined here includes Spearman’s rho and Gini’s measure of association as special cases.

Bonding of Ultra High Molecular Weight Polyethylene to Styrene-Butadiene Rubber

1993 ◽  
Vol 66 (1) ◽  
pp. 92-97 ◽  
Author(s):  
Gary R. Hamed ◽  
Hasan S. Dweik
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Average Molecular Weight ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Order Of Magnitude ◽  
High Bond ◽  
Styrene Butadiene ◽  
Ultra High Molecular Weight

Abstract The adhesion between a sulfur-vulcanized SBR and polyethylenes (PE) of various molecular weights has been determined using a T-peel geometry. When the viscosity average molecular weight of the polyethylene exceeds about 700 k, bonding is sufficient to cause rubber tear during peeling. In contrast, with PE of Mv≈147k, joint strength is reduced by more than an order of magnitude and fracture proceeds between the SBR and PE. It is hypothesized that the high bond strength with the ultra high molecular weight polyethylene (UHMWPE) is due to the formation of entrapped tangles between chains of the two adherends. Consistent with this, SBR-UHMWPE bonds are not disrupted after extensive swelling in toluene.

A Proposed Method for Estimating Polymer Molecular Weight Distribution without Fractionation

1961 ◽  
Vol 34 (2) ◽  
pp. 453-460
Author(s):  
John Rehner
Keyword(s):  
Molecular Weight ◽  
Distribution Function ◽  
Present Method ◽  
Crosslink Density ◽  
Low Molecular Weight ◽  
Polymer Molecular Weight ◽  
Critical Test ◽  
Molecular Weights ◽  
Experimental Values ◽  
Better Than

Abstract The close agreement which Green has demonstrated between results from the Schulz binomial and the Tung distribution and the applicability of the latter to a variety of fractionation data for different polymers both seem to outweigh possible objection that the present method assumes a particular distribution function. Green's results suggest to us that the apparent exceptions found by Tung for some polyethylenes containing large amounts of low molecular species may possibly be attributed to fractionation inefficiency, rather than to the inadequacy of his function. The internal consistency or smoothness of data does not, of course, constitute proof of precise fractionation. In fact, one can safely say it is no easy matter to find complete fractionation data, of established precision, that can provide a critical test of a distribution function over the entire molecular weight domain. In his study of polyethylenes, Tung suggested that his function tends to exaggerate the low molecular weight end of the distribution, in the sense that the Mn values calculated from his parameters were only about half as large as those obtained by summation of the experimental data for the fractions. His calculated and experimental values of Mw, on the other hand, were in satisfactory agreement. One might be tempted to use this to reconcile the Mn values of the SBR system in Table II with the higher values reported by others. However, this procedure would be indefensible because simply doubling the Mn values would give polydispersity values of less than unity. It would therefore seem incorrect to generalize that the Tung function gives abnormally small Mn values for all polymers, especially when there is some reason to believe that it is better than it seems, even for polyethylenes. Much more likely, the differences between the average molecular weights and the polydispersity of the peroxide-SBR system of Table II, and the corresponding quantities reported by Bueche and Harding for sulfur-SBR and by Booth and Beason for uncompounded SBR, are real and are due to chemical and other factors already mentioned. Although the meager data at hand leave some question as to the accuracy with which the present method can predict absolute values of the various average molecular weights, the key to the matter seems to be the ratio of the true to the physically measured crosslink density for polymers in general, rather than the particular distribution function employed here. Less uncertainty is attached to the polydispersity, since this is a function of only one parameter, b, which is quite insensitive even to large errors in ρ. The method may therefore be useful, even in its present state, for comparative studies in a given system. These might include, for example, the effect of synthesis or processing variables on distribution characteristics and product properties or the effects of stabilizers in aging or other degradative processes.

Fermentpolymerisation VI

1964 ◽  
Vol 19 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Von H. Ebert ◽  
H. Stricker
Keyword(s):  
Molecular Weight ◽  
Kinetic Data ◽  
Sedimentation Analysis ◽  
Enzyme Preparations ◽  
Molecular Weights ◽  
Stability Measurements

The action of levan sucrase from aerobacter levanicum on sucrose can be divided into three reactions: levan formation, inversion and oligosaccharide formation. As in dextran synthesis, levan has extremely high molecular weights which are formed even at very small conversions. The oligosaccharides consist mainly of 1β-fructosyl sucrose.From kinetic data of reactions with enzyme preparations which have been prepared on sucrose containing cultivation media, we could conclude that a levanase was present in our enzyme preparations. By application of fructose instead of sucrose in our cultivation media we could get enzyme preparations completely free of levanase and levan. Temperature- and pH-stability measurements and kinetic data lead to the conclusion that all three reactions are catalysed by the same enzyme. This was confirmed by investigations in the ultracentrifuge; the molecular weight of the enzyme as measured by sedimentation analysis was found to be 22 000.

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