Molecular Weight Dependence of Relaxation Spectra of Amorphous Polymers in the Rubbery Region. VIII. Comparisons of Experimental Relaxation Spectra of Commercial Synthetic Rubbers with those Estimated from Molecular Weight Distributions

1967 ◽  
Vol 40 (2) ◽  
pp. 484-492 ◽  
Author(s):  
Genichi Yasuda
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Mechanical Relaxation ◽  
General Validity ◽  
Relaxation Spectra ◽  
Molecular Weight Distributions ◽  
Synthetic Rubber ◽  
Weight Distributions

Abstract Synthetic rubber of different species, types, and degrees of mastication were used to examine the general validity of the proposed relationship between mechanical relaxation spectra in the rubbery region and molecular weight distribution. Results show that the proposed relationship can be well used to discuss quantitatively the role of molecular weight distribution in the theoretical behavior of a raw rubber while being processed.

Characterization of Elution Chromatography Fractions from CIS-Polybutadiene by GPC

1970 ◽  
Vol 43 (6) ◽  
pp. 1439-1450 ◽  
Author(s):  
W. V. Smith ◽  
S. Thiruvengada
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Low Molecular Weight ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Log Normal ◽  
Analytical Fractionation ◽  
Molecular Weight Fractions ◽  
Elution Chromatography

Abstract A preparative fractionation of about 23 g of a commercial cis-polybutadiene rubber is described. The method employed was a solvent elution chromatographic method with very little temperature gradient. The molecular weight distributions of the fractions obtained were determined by an analytical fractionation of 20 mg of polymer. The method was similar to the preparative fractionation and involved solvent elution chromatography. The fractions obtained were assayed for quantity, molecular weight, and molecular weight distribution by GPC. The low molecular weight fractions of the preparative fractionation had molecular weight distributions which could be closely approximated by two log normal distributions, the low molecular weight component having the narrower width. The ratio of weight to number average molecular weight was found to be about 1.1 for these samples. The higher molecular weight fractions could also be approximated by two log normal distributions; however, in these fractions the low molecular weight component had a very broad distribution but constituted only a small portion of the sample. The widths of the GPC curves of the fractions correlate satisfactorily with the molecular weight distributions found by the analytical refractionations. The GPC width is a sensitive criterion of the width of the molecular weight distribution even when only two columns are used. It is felt that the analytical fractionation procedure presented gives more detailed information on the molecular weight distribution than is easily obtainable from an ordinary GPC curve.

Simple and secure data encryption via molecular weight distribution fingerprints

2020 ◽  
Vol 11 (40) ◽  
pp. 6463-6470
Author(s):  
Jeroen H. Vrijsen ◽  
Maarten Rubens ◽  
Tanja Junkers
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Data Encryption ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Secure Data

A method for encryption and safe transmission of data in the shape of molecular weight distributions (MWD) is presented.

Controlling Molecular Weight Distributions Through the Mixing of Low Dispersity Polymer Samples: A Predictive Framework

2019 ◽  
Author(s):  
Maarten Rubens ◽  
Tanja Junkers
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Radical Polymerizations ◽  
Systematic Framework

<div>The physical properties of polymer samples are dependent on the overall shape and breadth of the molecular weight distribution (MWD). A small number of methods are available to tune the shape and characteristics of MWDs based on influencing controlled radical polymerizations and on mixing of individual distributions. However, no systematic framework exists to date to predict the characteristics and shapes of artificial MWDs prior the experiments. In this work we present such framework based on interpolation of individual distributions.</div>

Effect of Molecular Weight Distribution of Mineral Oil on Tribofailure of Spur Gears

1981 ◽  
Vol 103 (1) ◽  
pp. 210-218 ◽  
Author(s):  
F. Hirano ◽  
K. Ichimaru ◽  
K. Kinoshita ◽  
T. Sakai
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Film Formation ◽  
Spur Gears ◽  
Mineral Oils ◽  
Mild Conditions ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Failure Loads

Using a series of straight mineral oils with a variety of molecular weight distributions failure loads of spur gears with gear ratios 27:25 and 1:1 were investigated. The failure loads in the case of the synchronous engagement 1:1 were considerably higher than those in the asynchronous engagement 27:25 as a result of imprinting of asperities of harder teeth on softer engaged teeth. The correlation among the results was found to be quite regular, showing the beneficial effect of wide-ranged oils in the molecular weight distribution. Summarizing the obtained results, it is concluded that the failure loads of narrow-ranged oils were conditioned by their viscosity grades, and that those of wide-ranged oils increased further with the aid of oxide film formation on teeth. Results of four-ball tests and two-disk tests previously carried out under mild conditions using the same narrow-ranged and wide-ranged oils show the similar feature to those of the gear tests.

Molecular Weight Distributions of Elastomers—Comparison of Gel Permeation Chromatography with Other Techniques

1965 ◽  
Vol 38 (4) ◽  
pp. 823-831 ◽  
Author(s):  
Leon W. Gamble ◽  
Lowell Westerman ◽  
Ebnest A. Knipp
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Gel Permeation Chromatography ◽  
Molecular Weights ◽  
The Past ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Gel Permeation ◽  
Polymer Fractionation

Abstract During the past decade interest in polymer fractionation for evaluating molecular weight distribution has increased. New polymers, such as polypropylene, high density polyethylene and many others have been subjected to extensive characterization, but some older polymers, including natural rubber have not. In recent years column fractionation has received a great deal of attention; a review has been made by Schneider. Most of the techniques of polymer fractionation, such as precipitation from solution and column fractionation, are quite lengthy and require days or even weeks to complete. A more rapid method for molecular weight distribution has been the goal of polymer chemists for years. The most promising of the rapid methods are turbidimetric and gel permeation chromatography by which analysis is accomplished in a few hours. This paper discusses application of gel permeation chromatography to fractionation of elastomers. In addition this technique is compared with data from column fractionation, light scattering and osmometry. Some of the assumed factors used in converting gel permeation data into molecular weights are in error. But by calibration of the gel permeation chromatograph with classical methods reliable data can be obtained.

Processing of EPDM Polymers as Related to Structure and Rheology

1990 ◽  
Vol 63 (4) ◽  
pp. 540-553 ◽  
Author(s):  
Kenneth P. Beardsley ◽  
Richard W. Tomlinson
Keyword(s):  
Molecular Weight ◽  
Shear Rate ◽  
Carbon Black ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Flow Characteristics ◽  
Shear Stresses ◽  
Lower Shear ◽  
Molecular Weight Distributions ◽  
Weight Distributions

Abstract We have shown that the rate of mixing oil and carbon black with EPDM polymers having the same Mooney viscosity is dependent on their molecular-weight distribution and degree of branching. Samples having broad molecular-weight distributions mix more slowly than samples with more narrow distributions, and branched samples mix more slowly than corresponding linear samples. The slower mixing of samples that are branched or broad in molecular-weight distribution is a consequence of their more elastic character. These samples tend to be more non-Newtonian in their flow characteristics and thus have high viscosities at low shear rate and low viscosities at high shear rate. They also drop more in viscosity on mixing with oil. These factors cause these polymers to wet the carbon black more slowly and to have lower shear stresses during the mixing, leading to slower mixing.

Comparison of treatment efficiency and molecular weight distribution of membrane concentrate from textile wastewater

2016 ◽  
Vol 18 (2) ◽  
pp. 348-359
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Textile Wastewater ◽  
Anaerobic Treatment ◽  
Low Molecular Weight ◽  
Treatment Efficiency ◽  
Molecular Weight Distributions ◽  
Weight Distributions

<div> <p>This study investigated the treatability and changes in molecular weight distributions (MWD) of membrane concentrate. Nanofiltration (NF) concentrate from textile wastewater was subjected sole anaerobic treatment (R1) and pre-ozonation (R2) plus anaerobic treatment. BOD<sub>5</sub>, COD and TOC, color, sulphate and specific ultraviolet absorbtion at 254 nm (SUVA<sub>254</sub>) were analysed. Pre-ozonation improved the biodegradability of the membrane concentrate. The low molecular weight (LMW) organics was an important reason for the overall biodegradability enhancement of the membrane concentrate. Color was caused mainly by matters with higher than MWD of 10 kDa and 80% of HMW organics were removed during anaerobic treatment. Nearly half of sulfate was lower than 0.5 kDa which indicates that sulfate hardly treated by NF membranes. SUVA<sub>254</sub> values after anaerobic treatment were generally higher than 2 l mg<sup>-1</sup>m<sup>-1</sup> which indicates that membrane concentrate was in hydrophobic characteristics.&nbsp;</p> </div> <p>&nbsp;</p>

Controlling Molecular Weight Distributions Through the Mixing of Low Dispersity Polymer Samples: A Predictive Framework

2019 ◽  
Author(s):  
Maarten Rubens ◽  
Tanja Junkers
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Radical Polymerizations ◽  
Systematic Framework

<div>The physical properties of polymer samples are dependent on the overall shape and breadth of the molecular weight distribution (MWD). A small number of methods are available to tune the shape and characteristics of MWDs based on influencing controlled radical polymerizations and on mixing of individual distributions. However, no systematic framework exists to date to predict the characteristics and shapes of artificial MWDs prior the experiments. In this work we present such framework based on interpolation of individual distributions.</div>

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