Spectrophotometric Determination of the Styrene Content of Butadiene-Styrene Copolymers

1946 ◽  
Vol 19 (4) ◽  
pp. 1077-1084 ◽  
Author(s):  
E. J. Meehan
Keyword(s):  
Molecular Weight ◽  
Spectrophotometric Determination ◽  
Extinction Coefficient ◽  
Ultraviolet Spectrophotometry ◽  
Relative Precision ◽  
Specific Extinction Coefficient ◽  
Styrene Copolymers ◽  
Styrene Content ◽  
Butadiene Styrene

Abstract The ultraviolet absorption of polystyrene, with maximum absorption at 262 mµ, is due to the presence of phenyl residues in the polymer. The specific extinction coefficient is constant, i.e., independent of the molecular weight of the polymer. This shows that the extinction of the phenyl residues is additive. On the basis of this fact, it is shown that the styrene content of a butadiene-styrene copolymer (such as GR-S rubber) can be determined by ultraviolet spectrophotometry. The relative precision of the determination is about 1 per cent, the probable relative accuracy is about 3 per cent.

Comparison of Ultraviolet Absorption and Chlorine Analysis Methods for Composition of Butadiene-p-Chlorostyrene Copolymers

1947 ◽  
Vol 20 (1) ◽  
pp. 313-314 ◽  
Author(s):  
E. J. Meehan ◽  
T. D. Parks ◽  
H. A. Laitinen
Keyword(s):  
Extinction Coefficient ◽  
Spectrophotometric Method ◽  
Wave Length ◽  
Chloride Ion ◽  
Amperometric Titration ◽  
Specific Extinction Coefficient ◽  
Styrene Copolymers ◽  
Composition Determination ◽  
Butadiene Styrene

Abstract The percentage of chlorine in a copolymer containing chlorostyrene can be determined by amperometric titration of the chloride ion present after sodium fusion of the polymer. Since the percentage of chlorine is proportional to the percentage of chlorostyrene, the composition of a butadiene—chlorostyrene copolymer may be determined directly. This absolute method of composition determination affords a means of checking the ultraviolet spectrophotometric method which has been proposed for the determination of the composition of butadiene—styrene copolymers. In the application of the spectrophotometric method it is assumed that the specific extinction coefficient of the copolymer varies linearly with the percentage of styrene between the values of the same wave length for polybutadiene and polystyrene. The spectrophotometric measurements are made at 260.0 mµ or at 269.5 mµ for copolymers of butadiene with styrene or with p-chlorostyrene, respectively.

FURTHER DEVELOPMENTS IN THE VISTEX METHOD FOR THE DETERMINATION OF THE INTRINSIC VISCOSITY OF HIGH POLYMERS

1949 ◽  
Vol 27b (7) ◽  
pp. 666-681 ◽  
Author(s):  
D. A. Henderson ◽  
N. R. Legge
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Average Molecular Weight ◽  
Solvent Mixture ◽  
Gel Point ◽  
Styrene Copolymers ◽  
A Value ◽  
Pure Solvent ◽  
Butadiene Styrene

The intrinsic "vistex" viscosities of several series of butadiene–styrene copolymers of varying conversion and average molecular weight, dissolved directly from the latex in the vistex solvent mixture (toluene–isopropanol, 80/20 by volume), have been investigated and compared with the intrinsic viscosities of the corresponding coagulated, dried polymers dissolved in toluene. The intrinsic viscosity in toluene, [η]T, is related to the intrinsic vistex viscosity, [η]V, in toluene–isopropanol by the equation:—[Formula: see text]Hence, viscosity average molecular weight may be calculated from vistex measurements.A further development of the method has shown that, once the latex is dissolved in the vistex solvent, the solution may be diluted, within certain denned limits, by the addition of pure solvent (toluene) to obtain the several levels of concentration of polymer required for the determination of intrinsic viscosity. It is then possible, by extrapolation to zero concentration of polymer, to obtain a value for the intrinsic viscosity that is equal to the conventional intrinsic viscosity of the polymer in pure solvent after coagulation and drying under very mild conditions. The viscosity characteristics of butadiene–styrene copolymers of varying conversion appear to be represented, at conversions below the gel point, by the equation,[Formula: see text]where β′ and n are constants of the order of 0.25 and 1 for solutions in toluene and 0.1 and 2.5 respectively for vistex solutions. Distinct changes in β and/or n have been found at conversions in the region of and beyond the gel point.

Dependence of Tack Strength on Molecular Properties

1959 ◽  
Vol 32 (1) ◽  
pp. 48-66 ◽  
Author(s):  
W. G. Forbes ◽  
L. A. McLeod
Keyword(s):  
Molecular Weight ◽  
Shear Viscosity ◽  
Catalyst System ◽  
Chain Entanglement ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
The Difference ◽  
Catalyst Systems ◽  
Time Required ◽  
Butadiene Styrene

Abstract A method has been developed for the measurement of the tack strength of fresh and reproducibly smooth rubber surfaces. Using this method the tack strength of natural rubber is shown to be independent of polymer purity, and, to a large extent, Mooney viscosity, intrinsic viscosity, gel content and molecular weight distribution. The relative tack strengths of polyisoprenes of different molecular weights prepared in different catalyst systems are measured. The results are discussed in terms of microstructure. A study of the tack strength of oil-extended butadiene-styrene copolymers indicates that relative tack strength is related to the shear viscosity of the bulk polymer. Measurements of relative tack strength on Alfin and free radical butadiene-styrene copolymers, butyl, brominated butyl and butadiene-acrylonitrile copolymers confirm the inportance of shear viscosity in controlling tack strength. Choice of catalyst system and temperature of polymerization cause the largest variation in polymer viscosity. The contact time required for the relative tack strength to become unity is shown to be inversely dependent upon the value of the relative tack strength itself. Shear viscosity measurements are given for six classes of polymer and the values shown to correlate with relative tack strength. It is postulated that molecular weight (and probably also chain entanglement) is the controlling variable. The bond strength between two different uncured polymers is shown to depend upon the difference in cohesive energy densities of the two polymers.

Spectrophotometric Determination of Hydralazine Hydrochloride Tablets Using Ninhydrin

1983 ◽  
Vol 66 (6) ◽  
pp. 1455-1457
Author(s):  
Manesh C Dutt ◽  
Tju-Lik Ng ◽  
Lian-Tun Long
Keyword(s):  
Spectrophotometric Determination ◽  
Absorption Maximum ◽  
Room Temperature ◽  
Mass Spectrometric ◽  
Dilute Solutions ◽  
Ultraviolet Spectrophotometry ◽  
Buffer Solution ◽  
Colored Product ◽  
Hydralazine Hydrochloride

Abstract A method is described for the assay of hydralazine HC1 in tablets, based on the colored product formed by the reaction between hydralazine and ninhydrin. The reaction is conducted at room temperature in a pH 3 buffer solution and the colored product is measured spectrophotometrically at the absorption maximum at 442 nm. Under the stipulated conditions, this reaction is highly specific for hydralazine and is not affected by other drugs which may be used in combination with hydralazine. Results of infrared and mass spectrometric studies suggested that the colored product is a hydrazone. Ultraviolet spectrophotometry also showed that dilute solutions of hydralazine degrade rapidly in the presence of alcohols.

Styrene-Diene Resins in Rubber Compounding

1947 ◽  
Vol 20 (1) ◽  
pp. 241-248
Author(s):  
A. M. Borders ◽  
R. D. Juve ◽  
L. D. Hess
Keyword(s):  
Tensile Elongation ◽  
Chemical Properties ◽  
Aryl Hydrocarbon ◽  
Styrene Copolymers ◽  
Synthetic Rubber ◽  
Brittle Point ◽  
Styrene Content ◽  
Physical And Chemical ◽  
Preparation And Evaluation ◽  
Butadiene Styrene

Abstract Early in the investigation of butadiene-styrene copolymers as synthetic rubbers, this laboratory became interested in copolymers containing much more styrene than any of the American or German synthetics. This interest was soon directed to the resinous copolymers obtained when the styrene content is increased beyond the range in which rubberlike properties are observed at room temperature. The exploratory work, therefore, involved preparation and evaluation of butadiene-styrene copolymers containing from 65 to 98 per cent styrene. No description of similar polymers has been found. Konrad and Ludwig claimed the improvement of rubberlike properties of butadiene-styrene copolymers by increasing the styrene content from the normal range to “between about 47.5 and about 70 per cent”. The claims and examples of this patent emphasize the improvement of rubberlike properties, such as tensile, elongation, and rebound, at high temperatures. It is well known in this country, however, that increase in styrene content beyond a certain point, perhaps 50–55 per cent, is accompanied by a loss of overall balance of rubber characteristics. Therefore, the copolymers at the upper end of the range described by Konrad and Ludwig have definite limitations for rubber uses—for example, low rebound, high brittle point, shortness, etc. In the writers' laboratory useful resins have been prepared from dienes and vinyl aryl hydrocarbons in the range 5 to 20 per cent diene and 80 to 95 per cent vinyl aryl hydrocarbon. This paper describes the properties and certain uses of one of these copolymers containing approximately 15 parts of butadiene and 85 parts of styrene. This material possesses a combination of physical and chemical properties which permit its use in several applications where cyclized natural or synthetic rubbers are commonly employed. Cyclized natural rubber has been described by Bruson, Endres, and Thies and Clifford. Cyclized synthetic rubbers were described recently by Endres. One product of this type is made from a special synthetic rubber. The new 15 butadiene—85 styrene copolymer is now identified as Pliolite S-3, since it may be used in many Pliolite applications, often with distinct advantages over either the natural or synthetic rubber derivatives.

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