Isoprene and Rubber. Part 34. Molecules or Micelles in a Rubber Solution

1932 ◽  
Vol 5 (3) ◽  
pp. 265-277
Author(s):  
H. Staudinger ◽  
H. F. Bondy
Keyword(s):  
Colloidal Solutions ◽  
Dilute Solutions ◽  
Pure Nitrogen ◽  
Viscosity Measurements ◽  
Molecular Weights ◽  
Colloid Particles ◽  
Rubber Part ◽  
Complete Exclusion ◽  
The Individual ◽  
Viscous Solutions

Abstract Measurements of the Viscosity of Rubber Solutions In the literature may be found numerous measurements of the viscosity of rubber solutions, the object of which was to throw light on the nature of colloidal solutions and changes in these solutions by various operations. These investigations give no insight into the structure of colloid particles and the reason for changes in rubber solutions because they are based on false assumptions, particularly the assumption that rubber has a micellar structure. Often highly viscous solutions were studied, and though these appeared to be of special interest to the colloid chemist, they were unsuited for such investigations, for they are gel solutions in which the structure of the colloid particles is much more difficult to explain than is that in dilute solutions (sol solutions), where the molecules have freedom of movement and do not disturb one another. The earlier works also contain references to the sensitivity of rubber to oxygen, though no special precautions were ever taken in the measurements to exclude oxygen; in fact this was unnecessary as a rule, for crude rubber solutions are much more stable, because of anticatalysts present, than solutions of pure rubber in which these have been removed. Pure rubber was prepared by the method of Pummerer and Pahl and, as described in the following work, was separated by fractional extraction into portions of different average molecular weights. Viscosity measurements of the individual fractions were then carried out under various conditions. The study of the rubber solution, like that of the balata solution, must be carried out with complete exclusion of air, and the solvent (tetralin or benzene) must be distilled in an atmosphere of pure nitrogen and be freed of oxygen. The filtration of the rubber solution, the filling of the viscosimeter, as well as the measurements themselves, are likewise made in an atmosphere of pure nitrogen. Measurements were taken in the Ubbelohde viscosimeter at different pressures, as a rule at 10.30 and 60 cm. mercury pressure. Very dilute solutions were also measured in the Ostwald viscosimeter, since the deviations from the Hagen-Poiseuille law are of no great importance at low concentration. Finally, it should be mentioned that these special precautions during the viscosity measurements, above all the careful exclusion of air, are necessary only in the case of rubber, not with the saturated hydrocarbons, polystyrene, and hydrorubber.

A comparison of the compressibilities of some gases with that of nitrogen at pressures below one atmosphere

1950 ◽  
Vol 200 (1061) ◽  
pp. 201-218 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Differential Method ◽  
Linear Extrapolation ◽  
Volume Changes ◽  
Pure Nitrogen ◽  
Molecular Weights ◽  
Nitrous Oxide Oxygen ◽  
The Individual ◽  
Straight Lines ◽  
High Degree

A differential method for comparing the compressibilities of gases at pressures below 1 atm. has been developed in which many of the errors inherent in methods employed previously have been to a large extent eliminated, especially those due to meniscus volume changes and capillary depression. Using pure nitrogen as a standard the low-pressure isothermals of carbon monoxide, carbon dioxide, nitrous oxide, oxygen, ethylene and propane have been determined at a temperature of 22-05° C. The deviations of the individual points from straight lines do not in most cases exceed 2 parts in 100,000. In no case, even with propane, was any curvature in the isotherms detectable. The contention of Moles and other recent workers that the molecular weights of liquefiable gases can be determined to a high degree of accuracy by linear extrapolation is rendered highly probable by this fresh evidence.

Isoprene and Rubber. Part 44. Viscosity Measurements of Squalene and Hydrosqualene Solutions

1936 ◽  
Vol 9 (4) ◽  
pp. 573-578
Author(s):  
H. Staudinger ◽  
H. P. Mojen
Keyword(s):  
Physical Properties ◽  
General Relation ◽  
Basic Structure ◽  
Degree Of Polymerization ◽  
Specific Viscosity ◽  
Viscosity Measurements ◽  
Molecular Weights ◽  
Gutta Percha ◽  
Rubber Part

Abstract The physical properties of highly polymerized substances, which are composed of fiber molecules, depend on the lengths of the chains of these fiber molecules. Thus tensile strength, elasticity, tendency to swell in solvents, and above all viscosity, are dependent on the length of chain of the particular substance. Among the substances, the properties of which vary thus, are rubber, gutta-percha, and balata. Since the length of fiber molecules can vary within wide limits, such physical properties as those mentioned above show wide variations in the case of rubber, gutta-percha, and balata. This is evident for example by a comparison of the properties of unmasticated rubber, which consists of long fiber molecules of a degree of polymerization of 2000, with the properties of masticated rubber, the greatly dissociated molecules of which have a degree of polymerization of only 500. The determination of the length of the fiber molecules is therefore of great importance in the case of highly polymerized substances. It has already been proved in past experiments with members of a series of homologous polymers, i. e., of substances the macromolecules of which have the same basic structure and differ only in length, that the molecular weights can be determined from viscosity measurements. This determination is based on the fact that there is a general relation between the specific viscosity and the length of the dissolved molecules, which can be expressed by the formula:

An Investigation of the Viscosity of Rubber Solutions

1930 ◽  
Vol 3 (4) ◽  
pp. 604-611 ◽  
Author(s):  
C. M. Blow
Keyword(s):  
Molecular Weight ◽  
Mechanical Treatment ◽  
Viscosity Coefficient ◽  
Dilute Solutions ◽  
Viscosity Measurements ◽  
Molecular Weights

Abstract Viscosity measurements have frequently been made with rubber, and very many suggestions have been put forward to explain the cause of the changes of viscosity in rubber solutions. According to Staudinger (Kautschuk, 5, 128 (1929)), if measured under certain conditions, e. g., in dilute solutions where no irregularities are found, the viscosity can be used as a measure of the molecular weight of the dissolved substance. Fickentscher and Mark (Kolloid-Z., 49, 140 (1929)) even calculate from viscosity measurements the length of the molecule and hence relative molecular weights. It is well known that the viscosities of rubber solutions differ greatly and that mechanical treatment of the rubber decreases the viscosity of its solutions to a very large extent. The latter effect has been explained by Staudinger as well as by Fickentscher and Mark (loc. cit.) as a depolymerization. The latter authors calculate that the molecular weight of rubber decreases to one-third of the original if it is masticated for 225 minutes. It has further been pointed out recently by Herschel and Bulkley (Kolloid-Z., 39, 291 (1926)) that rubber solutions show irregularities in their viscosity, e. g., the viscosity is not linearly proportional to the pressure. (According to Poiseuille's formula for the rate of flow of a liquid through a capillary, the viscosity coefficient:

Isoprene and Rubber. Part 41. The Hydrogenation of Rubber and Balata

1934 ◽  
Vol 7 (3) ◽  
pp. 496-502
Author(s):  
H. Staudinger ◽  
E. O. Leupold
Keyword(s):  
Molecular Weight ◽  
Particle Sizes ◽  
Colloidal Solutions ◽  
Uniform Size ◽  
Micellar Structure ◽  
Molecular Weights ◽  
Rubber Particles ◽  
Rubber Part ◽  
Points Of View ◽  
Molecular Substances

Abstract Viscosity measurements of dilute solutions of rubber and of balata led to the following values for the size and form of the molecules of these hydrocarbons. It is therefore not a question of definition whether the particle sizes shown above are to be regarded as the molecular or the micellar weights of these substances, for here the concept of molecular weight has the same significance as in the case of lower molecular substances, i. e., the molecule comprises the sum of all atoms combined by normal, i. e., homopolar atoms. The only difference between low and high molecular substances is that low molecular substances are composed of molecules of uniform size, whereas high molecular substances are a mixture of homologous polymers, so that the values above refer to average molecular weights. These results, which explain the nature of colloidal solutions of rubber, are at variance with the views of most investigators of colloids, who ascribe a micellar structure to the rubber particles, and in this way explain the property which rubber has of forming colloidal solutions. This makes clear why until very recently explanations of the constitution of rubber have been open to question among these particular investigators themselves. In order to lend further support to our opinion, the reduction of rubber and balata and low molecular homologous polymeric hydrocarbons was undertaken from certain points of view, as shown in the work which follows.

Isoprene and Rubber. Part 45. Viscosity Measurements of Solutions of Rubber and Hydrorubber in Various Solvents

1936 ◽  
Vol 9 (4) ◽  
pp. 579-584
Author(s):  
H. Staudinger ◽  
H. P. Mojen
Keyword(s):  
Carbon Tetrachloride ◽  
Chain Length ◽  
Homologous Series ◽  
Chlorinated Solvents ◽  
Cellulose Derivatives ◽  
Specific Viscosity ◽  
Molecular Weights ◽  
Rubber Part ◽  
Viscous Solutions ◽  
Chain Lengths

Abstract It has been observed many times that solutions of the same concentration of rubber in various solvents show marked differences in viscosity. For example, solutions of rubber in chlorinated solvents such as carbon tetrachloride have higher viscosities than do solutions of the same concentration in benzene or benzine. These differences in viscosity are attributable to the fact that the rubber molecules are solvated in different ways in the various solvents. It may be further assumed that in a particular homologous series of polymers, all members, i. e., substances of both high and low molecular weights, are solvated in the same solvent in the same way, for only in this way is it possible to believe that the specific viscosity of solutions of like concentration increases with increase in the chain length, as has been found to be true of cellulose derivatives. In the previous experiments with squalene and hydrosqualene (cf. preceding article), the constants necessary for calculating molecular weights and chain member indices n were determined. The constants for carbon tetrachloride are higher than those for benzene. In the case of squalene, therefore, as in the case of rubber, carbon tetrachloride gives more viscous solutions than does benzene. If, now, rubbers and hydrorubbers are solvated in the same way as squalene and hydrosqualene, then the same chain lengths of an homologous series of rubber polymers would be obtained by calculations using constants derived from the simple compounds of the chain member index, and from this the degrees of polymerization, are calculated by means of these constants in the formula:

The R2-haplotype associated Asp2194Gly mutation in the light chain of human factor V results in lower expression levels of FV, but has no influence on the glycosylation of Asn2181

2003 ◽  
Vol 89 (03) ◽  
pp. 429-437 ◽  
Author(s):  
Richard Dirven ◽  
Hans Vos ◽  
Rogier Bertina ◽  
Marijn Kolfschoten
Keyword(s):  
Human Factor ◽  
Light Chains ◽  
Factor V ◽  
Missense Mutations ◽  
Wild Type ◽  
Molecular Weights ◽  
Apc Resistance ◽  
Increased Risk ◽  
The Individual ◽  
Lower Expression

SummaryThe R2 haplotype of the FV gene spans from exon 8 through 25 and comprises several strongly linked polymorphisms in the FV gene, including some missense mutations. Carriership of the R2-FV allele has been associated with reduced plasma FV levels, increased FV1/FV2 ratios and mild APC resistance. Some studies have reported that carriership of the R2-FV allele is associated with an increased risk of venous thombosis. At this moment, the individual contribution to the R2-associated phenotypes of the different mutations linked to the R2 haplotype of FV is unclear. The main objective of our study was to obtain insight in the influence of the R2-related Asp2194Gly mutation on FV expression, FV structure and FV function using B-domainless rFV mutants. Replacing Asp at position 2194 by Gly resulted in a more than threefold reduction of rFV expression compared to rFV wild-type. Therefore, we propose that the R2-linked Asp2194Gly mutation is an important determinant of the association of the R2-FV allele with lower FV levels. Furthermore, the light chains from Asp2194Gly containing rFV mutants showed similar molecular weights as the light chains of the non-glycosylated rFVwt or the plasma FV2 isoform, indicating that glycosylation at Asn2181 is not stimulated by the presence of a glycine in position 2194. Finally, the apparent K d for dissociation of the FXaVa complex (K 1/2Xa) was not higher in rFV mutants with the Asp2194Gly mutation than for rFVwt, suggesting that also the affinity for negatively charged phospho-lipids is not affected by substitution of Asp into Gly at position at 2194.

Isoprene and Rubber. Part 29. High Molecular Hydrorubbers

1932 ◽  
Vol 5 (2) ◽  
pp. 136-140
Author(s):  
H. Staudinger ◽  
W. Feisst
Keyword(s):  
Molecular Weight ◽  
Catalytic Reduction ◽  
Molecular Form ◽  
Average Molecular Weight ◽  
Molecular Size ◽  
Decomposition Products ◽  
Molecular Weights ◽  
Rubber Part ◽  
Derivatives Of ◽  
Suitable Process

Abstract The molecular concept in organic chemistry is based upon the fact that the molecules, whose existence is proved by vapor density determinations, enter into chemical reactions as the smallest particles. If now it is assumed that organic molecular colloids like rubber are dissolved in dilute solution in molecular form then it must be proved that in the chemical transposition of macromolecules as well no change in the size of the macromolecules occurs. In the case of hemicolloids, therefore for molecular colloids with an average molecular weight of 1000 to 10,000, this has been proved by the reduction of polyindenes, especially of polysterenes, to hydroproducts with the same average molecular weight, and also by the fact that cyclorubbers do not change their molecular weight upon autoöxidation. The molecular weights of hemi-colloidal hydrocarbons are therefore invariable. This is much more difficult to prove in the case of rubber, although there are many more ways in which unsaturated rubber can be transposed than the stable polysterenes, polyindenes, and poly cyclorubbers. In most of the reactions with rubber, as in its action with nitrosobenzene, oxidizing agents, hydrogen halides, and halogens, an extensive decomposition takes place as a result of the instability of the molecule, which is referred to in another work. Therefore derivatives of rubber are not formed, but derivatives of hemi-colloidal decomposition products. The catalytic reduction of rubber in the cold appears to be the most suitable process of making it react without changing its molecular size in order to prove that in a chemical transposition its molecular weight remains the same.

scholarly journals Storage Stability of Volatile Organic Compounds from Petrochemical Plant of China in Different Sample Bags

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Fenglei Han ◽  
Huangrong Zhong ◽  
Ting Li ◽  
Yongqiang Wang ◽  
Fang Liu
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Recovery Rate ◽  
Storage Stability ◽  
Petrochemical Plant ◽  
Pure Nitrogen ◽  
Molecular Weights ◽  
Volatile Organic ◽  
Protective Gas ◽  
The Impact

According to the emission characteristics of volatile organic compounds (VOCs) in the petrochemical plants of China, the storage stability of VOCs for two different bags, polyester aluminum (PEA) and polyvinyl fluoride (PVF), was investigated in this study by comparing the adsorption of gas samples. A series of experiments were carried out to study the impact of different factors of sampling in the petrochemical industry. The results showed that the C2∼C3 substances can be adsorbed by the Tedlar bag, and after being refilled with pure nitrogen, the VOCs adsorbed previously by the bag material can be released. The aromatic hydrocarbon VOCs with larger molecular weight had a relatively lower recovery rate than the smaller molecular weights. And the average recovery of PEA airbags was significantly better than that of PVF airbags for storing stationary VOCs in the refinery of China. More kinds of substances can be detected in the airbags that had been added with helium protective gas, and it had a higher recovery rate for both kinds of simple bags after 24 hours of storage time, which indicated that the airbags without protective gas had adsorbed these substances.

scholarly journals VIII. The combining volumes of hydrogen and oxygen

1916 ◽  
Vol 216 (538-548) ◽  
pp. 393-427 ◽  
Keyword(s):  
Chemical Method ◽  
Fundamental Constant ◽  
Atomic Weight ◽  
Arithmetic Mean ◽  
High Order ◽  
Molecular Weights ◽  
Physico Chemical ◽  
The Subject ◽  
The Individual

The measurement of the combining weights of hydrogen and oxygen has been the subject of so many researches of a high order of excellence that any fresh investigation of this fundamental constant must be submitted with considerable diffidence. Nevertheless, it must be noted that the results obtained by various observers differ appreciably. According to Clarke ( 1 ), the values obtained by Morley and Noyes, by reason of the accuracy of their methods and the close concordance of the individual determinations, outweigh the results of all other investigators. The atomic weight of oxygen being 16, that of hydrogen, according to Morley( 2 ), is 1˙00762, and according to Noyes ( 3 ), 1˙00787. (Clarke, on Noyes’ data, prefers the value 1˙00783.) It is, further, a significant fact that the arithmetic mean of all determinations discussed by Clarke, lies between these two values, which differ by 1 part in 4000. Both values are based on the gravimetric synthesis of water and are independent of a knowledge of the densities of the gases. A physico-chemical method of determining the relative molecular weights depends on the knowledge of the ratio of the densities, together with that of the combining volumes.

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