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.

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.

scholarly journals Polymeric Proanthocyanidins from Psidium guajava

2005 ◽  
Vol 73 (3) ◽  
pp. 113-125 ◽  
Author(s):  
Fadi Qa'dan ◽  
Frank Petereit ◽  
Adolf Nahrstedt
Keyword(s):  
Molecular Weight ◽  
Gallic Acid ◽  
13C Nmr ◽  
Psidium Guajava ◽  
Aqueous Acetone ◽  
Acetone Extract ◽  
Chemical Constitution ◽  
The Mean ◽  
Mean Molecular Weight

From the aqueous acetone extract of the leaves of Psidium guajava L. the flavanols catechin and gallocatechin, the procyanidins B1, B2, B3 and two prodelphinidins (gallocatechin - (4α→8) - catechin; gallocatechin - (4α→8) - gallo-catechin) were isolated. A more abundant proanthocyanidin polymer was also isolated, purified and its chemical constitution studied by 13C-NMR and phloroglucinol degradation. The mean molecular weight of the polymer was estimated to be about 9 to 10 flavan-3-ol-units with a ratio of procyanidin: prodelphinidin units at 2 : 1 some of which are derivatized by gallic acid.

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.

scholarly journals Studies in polymerization - II. A method for investigating the relation between the molecular weights and intrinsic viscosities of polymers, and its application to polystyrene

1948 ◽  
Vol 192 (1030) ◽  
pp. 329-339 ◽  
Keyword(s):  
Molecular Weight ◽  
Carbon Tetrachloride ◽  
Intrinsic Viscosity ◽  
Weight Distribution ◽  
Transfer Reaction ◽  
Degree Of Polymerization ◽  
Simple Method ◽  
Absolute Value ◽  
Molecular Weights ◽  
Vinyl Polymers

A simple method for investigating the relation between intrinsic viscosity and molecular weights of vinyl polymers is described. Unbranched polystyrene is found to obey Houwink’s law with an exponent of 0·65. Equations are given for calculating the number average degree of polymerization and molecular weight distribution in unfractionated polymers. It is pointed out that a method is now available for the preparation of polymers with known molecular weights and distribution. The absolute value of the velocity constant for the transfer reaction between styrene and carbon tetrachloride at 60° C is calculated.

The Properties of Weak Solutions of N-Vinylpyrrolidone and Methyl Methacrylate Copolymers in Dimethylformamide

2017 ◽  
Vol 44 (12) ◽  
pp. 23-28
Author(s):  
O.I. Nikolaeva ◽  
T.S. Usacheva ◽  
T.A. Ageeva ◽  
O.I. Koifman
Keyword(s):  
Molecular Weight ◽  
Methyl Methacrylate ◽  
Intrinsic Viscosity ◽  
Weak Solutions ◽  
Mean Square ◽  
Influence Of Temperature ◽  
Methacrylate Copolymers ◽  
Huggins Constant ◽  
The Mean ◽  
Mean Square Distance

The rheology of solutions of N-vinylpyrrolidone and methyl methacrylate copolymers in dimethylformamide in the temperature range 20–35°C was studied. The influence of temperature and of the molecular weight and composition of the copolymers on their interaction with the solvent was shown, expressed quantitatively in terms of intrinsic viscosity, the Huggins constant, and the mean square distance between the ends of the macromolecular chains.

scholarly journals Osmometry with single Sephadex beads

1970 ◽  
Vol 119 (1) ◽  
pp. 67-73 ◽  
Author(s):  
A. G. Ogston ◽  
J. D. Wells
Keyword(s):  
Molecular Weight ◽  
Polyvinyl Alcohol ◽  
Osmotic Pressure ◽  
High Molecular Weight ◽  
Molecular Form ◽  
Degree Of Polymerization ◽  
Significant Extent ◽  
Fine Needle ◽  
Single Bead ◽  
Time Required

1. The measurement of osmotic pressure by means of a single bead of Sephadex (Edmond, Farquhar, Dunstone & Ogston, 1968) has been made more precise by immobilizing the bead on a fine needle. The design, calibration and use of the osmometer are described. 2. The method is particularly suitable for measuring high osmotic pressures in solutions of high-molecular-weight solutes, which must not penetrate the Sephadex to a significant extent. 3. With Sephadex G-50 the limit of precision is about 1.5cmH2O and the lower limit of molecular weight for a solute of compact molecular form is about 105. 4. The time required for each equilibration is less than 10min. 5. An impaled bead can be stored in the dry state without affecting its calibration. 6. Measurements on a sample of polyvinyl alcohol, degree of polymerization stated as 1750±50, gave ¯mn 43000±3000 and A2 (6.0±0.24)×10−4.

scholarly journals Elucidation of the Relationship between Intrinsic Viscosity and Molecular Weight of Cellulose Dissolved in Tetra-N-Butyl Ammonium Hydroxide/Dimethyl Sulfoxide

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1605 ◽  
Author(s):  
Bu ◽  
Hu ◽  
Yang ◽  
Yang ◽  
Wei ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Dimethyl Sulfoxide ◽  
Intrinsic Viscosity ◽  
Molecular Level ◽  
Ammonium Hydroxide ◽  
Degree Of Polymerization ◽  
Regenerated Cellulose ◽  
Natural Cellulose ◽  
The Relationship

The determination of molecular weight of natural cellulose remains a challenge nowadays, due to the difficulty in dissolving cellulose. In this work, tetra-n-butylammonium hydroxide (TBAH) and dimethyl sulfoxide (DMSO) aqueous solution (THDS) were used to dissolve cellulose in a few minutes under room temperature into true molecular solutions. That is to say, the cellulose was dissolved in the solution in molecular level, and the viscosity of the solution is linearly dependent on the concentration of cellulose. The relationship between the molecular weight of cellulose and the intrinsic viscosity tested in such dilute solutions has been established in the form of the Mark–Houwink equation, η=0.24×DP1.21. The value of 1.21 indicates that the cellulose molecules dissolve in THDS quite well. The cellulose dispersion in the THDS was proved to be in molecular level by atomic force microscope (AFM) and dynamic light scattering (DLS). The reliability of the established Mark–Houwink equation was cross-checked by the gel permeation chromatography (GPC) and traditional copper (II) ethylenediamine (CED) method. No considerate degradation was observed by comparing the intrinsic viscosity and the degree of polymerization (DP) values of the original with and the regenerated cellulose samples. The natural cellulose can be molecularly dispersed in the multiple-component solvent (THDS), and kept stable for a certain period. A time efficient and reliable method has been supplied for determination of the degree of polymerization and the molecular weight of cellulose.

Sign in / Sign up

Export Citation Format

Share Document