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Cellulose molecular weight distribution

Membrane stmcture is a function of the materials used (polymer composition, molecular weight distribution, solvent system, etc) and the mode of preparation (solution viscosity, evaporation time, humidity, etc). Commonly used polymers include cellulose acetates, polyamides, polysulfones, dynels (vinyl chloride-acrylonitrile copolymers) and poly(vinyhdene fluoride). [Pg.294]

Scarcely had the covalent chain concept of the structure of high polymers found root when theoretical chemists began to invade the field. In 1930 Kuhn o published the first application of the methods of statistics to a polymer problem he derived formulas expressing the molecular weight distribution in degraded cellulose on the assumption that splitting of interunit bonds occurs at random. [Pg.23]

Figure 4.23 Molecular weight distribution of a carboxynethyl-cellulose sasple. Coluiui combination of LiChrospher Si-100 and Si-500 mobile phase 0.5 H aqueous sodium acetate, pH 6, and flow rate 0.5 ml/min. Figure 4.23 Molecular weight distribution of a carboxynethyl-cellulose sasple. Coluiui combination of LiChrospher Si-100 and Si-500 mobile phase 0.5 H aqueous sodium acetate, pH 6, and flow rate 0.5 ml/min.
Mark returned to research after the modernization program was organized and operating smoothly. Limited to cellulose chemistry by the necessity of commercial feasibility, he studied cellulose acetate and the effect of the degree of acetylation on product solubility. At the same time he worked closely on the development of suitable analytical methods to measure molecular weight distribution and the degree of functionality. [Pg.81]

The prime object of the present study was to determine the compositional polydlspersity of commercial cellulose triacetate and to examine the effect of molecular weight and molecular weight distribution on the mechanical properties of the fibres. [Pg.366]

Narrow Molecular Weight Triacetate Calibration. A linear relationship was found when log against the elution volumes of various cellulose triacetate fractions was plotted. For narrow molecular weight distribution triacetate fractions, the GPC experimental average molecular weight, termed can be expected to conform... [Pg.369]

A relationship has been developed by means of which more valid values are obtained by GPC for the average degrees of polymerization for cellulose. This can be extended to other polymers. With automation of data acquisition and computer processing of data, a differential molecular weight distribution and complete information on DP of the sample are available in very short order with a low degree of error. The ready availability of narrow, well characterized polystyrene fractions for calibration makes this procedure highly attractive in view of the lack of similar standards of cellulose. [Pg.191]

VI. Molecular Weight Averages and Molecular Weight Distribution of Cellulose Nitrate... [Pg.193]

Fig. 4 Left Fluorescence, MALLS (90°) and RI signals from a CCOA-labeled cellulose sample. Right Differential molecular weight distribution and degree of substitution of carbonyl groups (DSco) as calculated from the detector outputs... Fig. 4 Left Fluorescence, MALLS (90°) and RI signals from a CCOA-labeled cellulose sample. Right Differential molecular weight distribution and degree of substitution of carbonyl groups (DSco) as calculated from the detector outputs...
A second and distinct era in the development of branched macromolecular architecture encompasses the time between 1940 to 1978, or approximately the next four decades. Kuhn 151 published the first report of the use of statistical methods for analysis of a polymer problem in 1930. Equations were derived for molecular weight distributions of degraded cellulose. Thereafter, mathematical analyses of polymer properties and interactions flourished. Perhaps no single person has affected linear and non-linear polymer chemistry as profoundly as P. J. Flory. His contributions were rewarded by receipt of the Nobel Prize for Chemistry in 1974. [Pg.17]

Preparation of Cellulose Derivative Samples with Narrow Molecular Weight Distribution... [Pg.20]


See other pages where Cellulose molecular weight distribution is mentioned: [Pg.392]    [Pg.392]    [Pg.11]    [Pg.180]    [Pg.258]    [Pg.511]    [Pg.561]    [Pg.112]    [Pg.18]    [Pg.133]    [Pg.103]    [Pg.130]    [Pg.81]    [Pg.42]    [Pg.766]    [Pg.2]    [Pg.83]    [Pg.489]    [Pg.193]    [Pg.193]    [Pg.194]    [Pg.198]    [Pg.134]    [Pg.144]    [Pg.780]    [Pg.60]    [Pg.35]    [Pg.36]    [Pg.176]    [Pg.185]    [Pg.204]    [Pg.179]    [Pg.180]    [Pg.243]    [Pg.116]    [Pg.56]   
See also in sourсe #XX -- [ Pg.187 ]

See also in sourсe #XX -- [ Pg.103 ]




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