Results 251 to 260 of about 1,678,407 (282)

Molecular Weight Distributions in Polycondensation

Journal of Macromolecular Science: Part A - Chemistry, 1971
Abstract The distribution of molecular sizes for an equilibrium polycondensation process is derived kinetically. The expressions obtained for the system at equilibrium are formally the same as those derived by Flory. The expressions differ however, in that the i-mer concentration is shown to depend on both the polymer and by-product equilibrium ...
J. G. Watterson, J. W. Stafford
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Determination of Molecular Weights and Molecular Weight Distribution of Polyacrylamides

SPE Annual Technical Conference and Exhibition, 1984
ABSTRACT A high-performance, size-exclusion chromatography procedure has been developed for determining molecular weights and molecular weight distributions of polyacrylamides. The procedure can be applied to dry or emulsion polyacrylamides. Virgin polymers and polymers passed through Berea sandstone cores can be analyzed. The analytical
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Determination of Molecular Weight and Molecular-Weight Distribution

1977
Molecular-weight determination methods can be classed as absolute, equivalent, or relative. Absolute methods allow the molecular weight to be calculated directly from the measured quantities; a knowledge of the physical and chemical structure of the molecules is not required.
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Molecular Weight Distributions in Polymerization

Journal of Macromolecular Science: Part A - Chemistry, 1974
Abstract Molecular weight distributions corresponding to three separate termination kinetics are derived using an approximation which is valid for large degrees of polymerization. The derivation is straightforward and suitable for introducing students to the significance of kinetics on molecular weight distributions.
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Narrow molecular weight distribution polystyrenes

Journal of Polymer Science Part A: General Papers, 1963
AbstractA study of the scope and limitations of the anionic polymerization of styrene and substituted styrenes under conditions in which a chain termination reaction is lacking was made. Under these conditions polymers of very narrow molecular weight distributions were obtained. Ultracentrifuge data are presented as evidence confirming the formation of
F. M. Brower, H. W. McCormick
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Modality of molecular weight distributions

Polymer Engineering & Science, 1990
AbstractEven restricting attention to weight distributions, it is ambiguous to merely say that a polymer is “not bimodal.” A simple example is shown wherein the weight distribution of log (molecular weight) is bimodal, but the weight distribution of molecular weight is not bimodal.
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Manipulating Polymer Molecular Weight Distribution

C&EN Global Enterprise, 2016
A typical polymer sample contains a variety of chain sizes. The average molecular weight of these chains, as well as the breadth and shape of their distribution, can influence bulk polymer properties. Adjusting how quickly a polymerization initiator is added can help tune that distribution, report Dillon T. Gentekos, Lauren N. Dupuis, and Brett P. Fors
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Molecular Weight Averages and Distribution

1999
Since a synthetic polymer is an assembly of molecules having different molecular weights (MW), the MW value has to be expressed as an average, and several different MW averages are defined (see Chap. 1). These MW averages are measured by different chemical and physical methods and are also calculated statistically in SEC by different equations ...
Sadao Mori, Howard G. Barth
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Molecular weight distribution of nisin

Biochimica et Biophysica Acta (BBA) - Protein Structure, 1968
B, Jarvis, J, Jeffcoat, G C, Cheeseman
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Molecular weight and molecular weight distribution

2000
Kenji Kamide, Toshiaki Dobashi
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