OSMOTIC PRESSURE MEASUREMENT AND THE INSTABILITY OF HIGH POLYMERS

1947 ◽  
Vol 25b (3) ◽  
pp. 301-321 ◽  
Author(s):  
A. F. Sirianni ◽  
L. M. Wise ◽  
R. L. McIntosh
Keyword(s):  
Molecular Weight ◽  
Osmotic Pressure ◽  
Intrinsic Viscosity ◽  
Polyvinyl Acetate ◽  
Elevated Temperatures ◽  
Molecular Shape ◽  
Quantitative Agreement ◽  
Weight Changes ◽  
Weight Variation ◽  
A Cell

In attempting to obtain accurate osmotic data in the low concentration range, it was found that the results were influenced by the diffusion of solvent from the cell through the membrane gasket. This behaviour was prevented by auxiliary sealing in a cell of new design, and results obtained with the improved cell are compared with those obtained with previous types of osmometer. A partial re-examination of the influence of preparation of the membrane was made in order to check results reported by Robertson, McIntosh, and Grummitt, and the different behaviour of caustic swollen and water swollen cellophane membranes has been confirmed, although quantitative agreement for water swollen membranes between the two investigations was not obtained. Using caustic treated membranes the molecular weight of a polyvinyl acetate sample was found to be the same within experimental error in three solvents.Further results on the changes in intrinsic viscosity and molecular weight brought about by ageing at elevated temperatures in the presence and absence of oxygen are reported for polyvinyl acetate and polymethyl methacrylate. It appears that oxygen is necessary to bring about molecular weight changes, and the degradation is due to scission of the chains at weak points. The evidence also suggests that changes in molecular shape may occur, since intrinsic viscosity values altered in some cases without evidence of molecular weight variation. This last observation is apparently outside the limits of error in reproducing osmotic pressure values.

The Chemical Constitution of Chlorinated Rubber

1951 ◽  
Vol 24 (3) ◽  
pp. 662-663
Author(s):  
René Allirot
Keyword(s):  
Molecular Weight ◽  
Osmotic Pressure ◽  
Hydrogen Chloride ◽  
Intrinsic Viscosity ◽  
Hydrogen Content ◽  
Degree Of Polymerization ◽  
Prolonged Action ◽  
Chlorinated Compounds ◽  
Chemical Constitution ◽  
The Mean

Abstract The results of the work described in the present paper indicate that, by the prolonged action of chlorine on polyisoprenes, chlorinated compounds corresponding to the composition (C10HxCl7)n are formed, irrespective of the molecular weight. The exact hydrogen content of these products can be calculated from determinations of the hydrogen chloride evolved in the reaction, and measurements to this end are in progress. Furthermore, determinations of the osmotic pressure and intrinsic viscosity, which have already been undertaken, should make it possible to determine with certainty the mean degree of polymerization of each fraction.

OSMOTIC PRESSURE, MOLECULAR WEIGHT, AND VISCOSITY OF SODIUM ALGINATE

1950 ◽  
Vol 28b (3) ◽  
pp. 105-113 ◽  
Author(s):  
F. G. Donnan ◽  
R. C. Rose
Keyword(s):  
Molecular Weight ◽  
Sodium Chloride ◽  
Osmotic Pressure ◽  
Sodium Alginate ◽  
Intrinsic Viscosity ◽  
Degree Of Polymerization ◽  
Low Concentrations

This work shows how the molecular weight of sodium alginate can be determined by measuring the values of the osmotic pressure, P, in the presence of low concentrations of sodium chloride, and extrapolation of P/C to C = 0, where C is the concentration of sodium alginate. For different samples of sodium alginate the slope of the curve P/C against C was independent of the molecular weight. Molecular weight values from 48,000 to 186,000 were obtained. The intrinsic viscosity of the different samples were linearly related to the degree of polymerization.

scholarly journals Characterization of a Novel Fructosyltransferase from Lactobacillus reuteri That Synthesizes High-Molecular-Weight Inulin and Inulin Oligosaccharides

2002 ◽  
Vol 68 (9) ◽  
pp. 4390-4398 ◽  
Author(s):  
S. A. F. T. van Hijum ◽  
G. H. van Geel-Schutten ◽  
H. Rahaoui ◽  
M. J. E. C. van der Maarel ◽  
L. Dijkhuizen
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Lactobacillus Reuteri ◽  
Bacterial Strains ◽  
Potential Health ◽  
Isolation And Characterization ◽  
A Cell ◽  
Encoding Gene ◽  
First Time

ABSTRACT Fructosyltransferase (FTF) enzymes produce fructose polymers (fructans) from sucrose. Here, we report the isolation and characterization of an FTF-encoding gene from Lactobacillus reuteri strain 121. A C-terminally truncated version of the ftf gene was successfully expressed in Escherichia coli. When incubated with sucrose, the purified recombinant FTF enzyme produced large amounts of fructo-oligosaccharides (FOS) with β-(2→1)-linked fructosyl units, plus a high-molecular-weight fructan polymer (>107) with β-(2→1) linkages (an inulin). FOS, but not inulin, was found in supernatants of L. reuteri strain 121 cultures grown on medium containing sucrose. Bacterial inulin production has been reported for only Streptococcus mutans strains. FOS production has been reported for a few bacterial strains. This paper reports the first-time isolation and molecular characterization of (i) a Lactobacillus ftf gene, (ii) an inulosucrase associated with a generally regarded as safe bacterium, (iii) an FTF enzyme synthesizing both a high molecular weight inulin and FOS, and (iv) an FTF protein containing a cell wall-anchoring LPXTG motif. The biological relevance and potential health benefits of an inulosucrase associated with an L. reuteri strain remain to be established.

Effect on Polymer Chain Structure Caused by the Molar Fraction of 4-Hydroxybutyrate in Poly(3-hydroxybutyrate- co -4-hydroxybutyrate)

2012 ◽  
Vol 602-604 ◽  
pp. 776-780
Author(s):  
Zhi Qiang Li ◽  
Mei Li ◽  
Wei Jia Fan
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Polymer Chain ◽  
Molar Fraction ◽  
Chain Structure ◽  
The Other ◽  
Mean Square ◽  
Polarizing Microscope ◽  
Other Hand ◽  
The Mean

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)copolymer [P(3HB-co-4HB)] is a kind of biodegradable high molecular polymer produced by bioaccumulation. Because of the good biodegradability and biocompatibility, P(3HB-co-4HB)s have attracted wide attention . At first, the intrinsic viscosity[η] in good solvent of P(3HB-co-4HB) s with varying contents of 4HB was investigated in different temperature. Second, observed the changes of crystallization gathered state caused by the varying contents of 4HB by polarizing microscope. The results show that to the P(3HB-co-4HB)s in same molecular weight, the intrinsic viscosity[η] in good solvent barely changes when the mole fractions of 4HB increase. On the other hand, the mean square end to end distances[0] of macromolecular flexible chains increase with the mole fractions of 4HB. At the same time, the states of aggregation change from spherulites to dendrites. In this investigation, we discuss the reasons of the differences in depth.

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