bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Statistical Length of Long-Chain Molecules
Authors: Treloar L. R. G. 
Published: February 2011

Abstract
A formula is derived for the complete function representing the probability of a given distance between the ends of a chain of universally jointed equal links. The formula is computed for chains of 25 and 100 links. The distribution functions derived from this formula are compared with those previously worked out by an independent method for polyisoprene and paraffin chains. It is shown that the polyisoprene chain is statistically equivalent to a randomly-jointed chain of length corresponding to 1.42 links per isoprene unit. This work forms part of a program of fundamental research on rubber undertaken by the Board of the British Rubber Producers' Research Association.
Preparation and Properties of Rubberlike High Polymers. I. Polymerization of Dienes and Vinyl Compounds in Bulk
Authors: Koningsberger C. , Salomon G. 
Published: February 2011

Abstract
The polymerization of dienes under the influence of heat, of diazoaminobenzene, and of benzoyl peroxide has been studied. Diazoaminobenzene probably acts as a slow but continuous source of free radicals, giving quantitative yields of methyl rubber of good quality from dimethylbutadiene after a few days to a few weeks at 100–125° C. The effect of diazoaminobenzene on butadiene is the same, but the rate of the uncatalyzed dimerization of butadiene at 100° C is as fast as that of dimethylbutadiene at 150° C and, therefore, dimerization interferes much more strongly with the polymerization of butadiene. Only 60 per cent of polybutadiene has been obtained. A few experiments with isoprene showed its position between the two other dienes. The effect of benzoyl peroxide on the polymerization of the dienes appeared to be much smaller than was expected from its known catalytic action on the polymerization of vinyl compounds, e.g., styrene, for in this case its activity is about 100–1000 times greater than that of diazoaminobenzene. It is assumed that a larger number of radicals, produced by the fast decomposition of benzoyl peroxide, causes this difference. Diazoaminobenzene has about the same effect on the polymerization of styrene and acrylonitrile as on that of dienes. The catalytic effect of benzoyl peroxide on the polymerization of dienes is, on the contrary, 10,000–100,000 times smaller than on that of vinyl compounds. This difference can be understood by the assumption that the catalyst is quickly used up by oxidizing the dienes and their polymers. Whereas methyl rubber and the polyisoprene resemble raw natural rubber, polybutadiene, prepared under comparable conditions, is hard, swells moderately, and has a tendency to become brittle as a result of oxidation (aging).
Spectrophotometric Determination of the Styrene Content of Butadiene-Styrene Copolymers
Authors: Meehan E. J. 
Published: February 2011

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.
An X-Ray Study of Some Synthetic Elastomers. Polychloroprenes
Authors: Fournier Henri , Trillat Jean Jacques 
Published: February 2011

Abstract
Synthetic rubbers prepared from isoprene and other unsaturated hydrocarbons have been studied by means of x-rays by various investigators, including Carothers, Katz, Meyer, and Sebrell and Dinsmore. In general, these synthetic products differ markedly from natural rubber in that when they are stretched, they do not give any fibre diagrams. On the contrary, μ-polychloroprene (Neoprene), H2C:CC·CH:CH2, when stretched to about 500 per cent, gives a somewhat diffused fibre diagram with an identity period of 4.8 A˚.U., corresponding to the length of a chloroprene unit in the trans form. We have verified this fact, and have found, in addition, that preliminary heating of the polychloroprene facilitates this orientation process which takes place upon stretching. The investigation was continued by a study of a product which had not previously been studied, viz., chloroisoprene:
The Structure of Some Synthetic Elastomers. Ethylene Polysulfide
Authors: Trillat Jean Jacques , Tertian Robert 
Published: February 2011

Abstract
As a result of x-ray studies of different synthetic elastomers a number of works have been published which show that, in general, these products behave somewhat differently from natural rubber. When stretched, some elastomers, e.g., Buna-S and Buna-N, show no evidence at all of crystallization; others, e.g., Neoprene and Vistanex, show much less well defined indications of crystallization than does natural rubber. These differences in behavior leave the field open to hypotheses regarding the origin of elasticity. As is well known, the condensation product of dichloroethane and sodium poly8ulfide gives rise to an ethylene tetrasulfide, which polymerizes in linear chains, ((CH2CH2S4)n. When mixed with suitable compounding ingredients and vulcanized, this polymer gives a substitute for rubber (Thiogomme and Thiokol), which can replace the latter in certain applications. Katz and Fuller have shown that stretched Thiogomme is capable of giving crystalline interferences, and a model of the elementary cell has been proposed by these investigators. The present authors have examined pure polymerized ethylene tetrasulfide and commercial Thiogomme, both when at rest and when stretched, utilizing for this purpose the Kα radiation of copper (λ=1.54 A˚.U.) The results which were obtained may be summarized as follows.
Vulcanization Reactions in Butyl Rubber. Action of Dinitroso, Dioxime, and Related Compounds
Authors: Rehner John , Flory Paul J. 
Published: February 2011

Abstract
Experiments have been carried out to determine the chemical reactions that occur when Butyl rubber is vulcanized by quinone dioxime or related compounds. Observations have been made of the reactions of these substances with simple olefins, and of the effect of oxidizing agents on the dioxime-type of vulcanization of Butyl in solution. The theory is proposed that, in the vulcanization of Butyl by quinone dioxime or its esters, in presence of oxidizing agents, the active agent is p-dinitrosobenzene formed by oxidation of the dioxime. Chemical reactions are suggested for the subsequent cross-linking or vulcanizing steps, and the results of confirmatory experiments are presented. p-Dinitrosobenzene and other polynitroso compounds are active vulcanizing agents for Butyl, natural rubber, Buna-S, Buna-N, and Neoprene, and do not require the addition of an oxidizing agent. It is suggested that vulcanization of natural rubber by polynitro compounds involves their reduction to corresponding nitroso compounds as the first step, and that the nitroso group adds to rubber to produce cross-linkages.
The Mobility of Foreign Molecules Dissolved in Rubber
Authors: Haegel Jean 
Published: February 2011

Abstract
Current theories of the elasticity of rubber view this property as originating in thermal agitation of the rubber molecules themselves. In any consideration of this problem, a major point to be considered is the degree of freedom of this agitation, first, because only segments of these very long molecules are concerned, and secondly because large brownian movements which might otherwise profoundly alter the structure are impossible. These phenomena should hold true also of rubber containing no solvent to swell it. A convenient means of studying thermal agitation of this character is to investigate the mobility of foreign molecules or segments of these molecules when they are dissolved in rubber. This can be done in a practical way by adding a colored substance to the rubber. Investigations already carried out in the laboratory have not completely settled this problem, but at least have led to rather unexpected results; it therefore seemed advisable to continue the study.
Crystallization of Rubber by Pressure
Authors: Thiessen P. A. , Kirsch W. 
Published: February 2011

Abstract
The knowledge which has been acquired as the result of studies by means of polarized light and x-rays of the behavior of rubber when stretched has led to the conclusion that rubber is a polyphase system, in which crystals and the liquid phase are in a state of equilibrium which depends not only on the temperature but to a considerable extent on the pressure. This concept is founded on the observation that there is an increase in the crystalline phase after rubber which has been stretched is allowed to rest, and that the anisotropy shows a reversible effect at definite temperatures and degrees of elongation. Experimental proof of this dependence on pressure has, however, been lacking heretofore, because investigations have been confined to unidirectional stretching, and consequently to pressure in one definite direction. If the conclusion stated above were correct, it would be expected that pressure from all directions would lead to crystallization under conditions whereby it would not otherwise occur. An experiment of this kind was planned at the time of the earlier work, has been in progress since then, and has recently been completed. The results are described in the present paper.
The Statistical Theory of the Elasticity of Rubber
Authors: Dostal H. 
Published: February 2011

Abstract
The theoretical investigations of various authors, with the aid of which the physical properties of rubber-like substances have become understood on a basis of intermolecular statistics, have not, at least from a quantitative point of view, kept pace with investigations relating to kinetic theories of gases. However, only the facts of rubber elasticity have become understood, and to point out one case, the coefficient of elasticity cannot be derived, and much less the tension zone, beyond proportionality. The reason for this is that, although statistics of a single chain molecule of finite size can be compiled, the bond of the chain molecule and, as a further instance, the behavior of a molecule of infinite size formed by interlacing have not been clearly understood up to the present time. Consequently, it has been possible to gain an insight into the statistical behavior of individual chain molecules much more easily than into that of a piece of rubber, and therefore to deduce with less difficulty theories of the viscosity of high molecular solutions and similar systems. In the case of rubber, progress has been more difficult in explaining the effects which take place.
Properties and Uses of Chlorinated Rubber
Authors: Baxter J. P. , Moore J. G. 
Published: February 2011

Abstract
Although rubber was first chlorinated in 1846 to improve its aging properties (Parks, British patent 11,147), it was not until 1888 that a product containing 65.18 per cent of chlorine was isolated and the formula C10H13Cl7 given by Gladstone and Hibbert. Nearly thirty years later the United Alkali Company marketed a solution of chlorinated rubber, Duroprene, made under the Peachey patents, and for ten years this remained the only chlorinated rubber on the market. During the past ten years interest in this material has rapidly developed, as shown by the numerous brands at present available, namely: Alloprene (I. C. I.) ; Tornesit (New York Hamburger Gummiwaaren Compagnie, later Chemische Fabrik Buckau); Tegofan (Tegofan Gesellschaft, later Chemische Fabrik Buckau); Pergut (I. G. Farbenindustrie) ; Detel (Detel Products) ; Aizen (Hadogaya Soda K. K., Japan); Nippon (Nippon Soda K. K., Japan) ; Protex (Soc. Ellettrica ed Elettrochimica del Caffaro, Italy); and Dartex (Metallgesellschaft A.-G.). The patent literature indicates that interest in chlorinated rubber is also taken by Russia, France, Austria, and Jugoslavia.
Rubber Elasticity and Gas Elasticity
Authors: Mark H. 
Published: February 2011

Abstract
All substances which are composed of long mobile chains show one peculiar property, highly reversible elasticity. Even though the range of temperature of this property may be notably variable (in the case of polyvinyl alcohol and rubber at about room temperature, in the case of polystyrene, sulfur, or Thiokol only at a higher temperature) still it is to be noted that for rubber-like elasticity the presence of long flexible chains is an indispensable factor. Thus, typical rubber elasticity occurs in polyvinyl alcohol (Vinarol), polybutadiene (Buna), polymethyl-butadiene (methyl rubber), polyacrylic ester and also in its mixed polymerisate with vinyl chloride. This type of elasticity occurs also in sinew fibrin and muscle fibrin, in polychlorobutadiene (Neoprene, Sovprene), in polyethylene sulfide (Thiokol, Baerite), polyphosphornitrile chloride and finally in vulcanized oils (factice) and also in elastic sulfur. In the cases so far examined (natural rubber, Buna, methyl rubber), it has been found that the coefficient of elasticity increases proportionally to the absolute temperature, and that during the stretching heat is evolved. This behavior is contrary to that of normal elastic materials, steel, quartz, glass, etc. It is striking that the substances which have this property of highly reversible (rubber-like) stretching are widely different chemically. This tempts one to ascribe that property to the similarity of their construction. For example, all the substances mentioned consist of long chain-molecules, which display a high degree of internal mobility. The number of members in these chains varies from 102 to 104 and their mobility is due to the kind of linkage between the members, mostly simple C—C bonds.
Values of the Physical Constants of Rubber
Authors: Wood L. A. 
Published: February 2011

Abstract
A critical survey has been made of the values of 16 basic physical constants of rubber in the fields of mechanics, heat, optics and electricity. The value for each constant which seems most reliable has been indicated and, when necessary, has been corrected to the standard conditions of normal atmospheric pressure and a temperature of 25° C. The values have been given for rubber in four different forms: purified hydrocarbon, commercial raw rubber, soft vulcanized rubber containing 2% combined sulfur and hard rubber containing 32% sulfur. The survey indicates that there are significant gaps in present knowledge of the fundamental properties of rubber. In some cases data are lacking, while in many others the best values available are not of the accuracy required for present-day scientific and industrial work. This paper may therefore serve not only as a summary of selected values of the different constants, but also as a basis for the planning of future investigations.
The Distribution of Combined Sulfur in Vulcanized Rubber and Its Bearing on the Sulfide Linkage Theory of Vulcanization
Authors: Williams I. 
Published: February 2011

Abstract
No direct evidence exists to support the sulfide linkage theory of vulcanization, which assumes that cross-linking of the molecules with sulfur would retain the elasticity and decrease the plasticity of the rubber. The following facts do not favor the sulfide linkage theory of vulcanization : (1) Vulcanized rubber can be peptized under conditions which do not appear to rupture a sulfide linkage. (2) No direct relation exists between the physical properties of vulcanized rubber and the amount of combined sulfur. (3) No direct relation exists between the ease of peptization and the physical properties of the vulcanizate. (4) Combined sulfur appears to assist the solvation of rubber. Rubber vulcanized with thiuram disulfides in the absence of free sulfur has poor physical properties but peptizes with difficulty. An increase in combined sulfur without a corresponding improvement in physical properties assists solvation. (5) Rubber having the best physical properties is also the most heterogeneous with respect to sulfur. The sulfide linkage theory would suggest that an even distribution of sulfur would produce the best physical properties. (6) Fractions of peptized vulcanizates, on evaporation of their solutions, leave insoluble vulcanized films, which shows that linkage by means of primary forces is unnecessary for producing the vulcanized condition.
The Interaction of Maleic Anhydride with Rubber
Authors: Bacon R. G. R. , Farmer E. H. 
Published: February 2011

Abstract
(1) Maleic anhydride is known to react (a) with conjugated compounds, e.g., butadiene, usually producing simple cyclic systems, and (b) with unsaturated olefinic substances like styrene and vinyl acetate, producing long-chain heteropolymers. It is now demonstrated that maleic anhydride, under the influence of a little benzoyl peroxide, will react in solution with rubber on heating, yielding a variety of tough, fibrous or resinous products. (2) It is shown that these derivatives are not produced by the action of maleic anhydride alone or of benzoyl peroxide alone, nor are they mixtures of rubber and maleic anhydride polymer. (3) As a result of the reaction, rubber has been found to undergo an increase in weight ranging from a few per cent up to about 120%, according to experimental conditions. The corresponding derivatives differ greatly from rubber in mechanical properties, and range from products which are tough, rubbery and non-tacky, to hard and brittle resins. (4) The effect of varying the quantity of benzoyl peroxide between 1% and 10%, and of using greater excess, is demonstrated. (5) The effect of varying the maleic anhydride/C5H8 ratio between 0.05 and 5 is demonstrated. (6) It is is shown that the nature of the solvent greatly influences the extent of reaction. The use of benzene, toluene, xylene, carbon terachloride, chloroform, decalin, and cyclohexane is discussed. (7) The influence of concentration and the occurrence of gelling have been investigated. (8) The derivatives are very different from rubber in their solubility characteristics.
An Accelerated Aging Test at Room Temperature
Authors: Marzetti B. 
Published: February 2011

Abstract
Accelerated aging in an oven, heated to a more or less elevated temperature, is one of the most valuable tests at the disposal of the rubber technologist for examining the behavior of different compounds in practical use. Geer in 1916 described a now well-established oven test at 160° F., he and Evans giving more details in 1921. In this latter paper they stated in particular that with proper use of their test, one day in the oven could be taken as equal to six months of natural life. Other attempts to foretell more exactly the natural life of rubber from accelerated aging data have proved useless. The figures obtained for life at different temperatures are not always in the same ratio, so that calculation of the corresponding times at room temperature depends on the temperature used in the heat test. This has been shown in experimental work of many authors, particularly Williams and Neal, Milligan and Shaw, Bierer and Davis, and Somerville and Russell. The matter has been thoroughly discussed in a “Symposium on Aging” presented before the New York Rubber Group of the American Chemical Society in 1929.
Rubber-Vulcanizing Properties of Colloidal Carbons
Authors: Wiegand W. B. , Snyder J. W. 
Published: February 2011

Abstract
1. Experiments with rubber-sulfur mixings showed that colloidal carbons accelerated vulcanization instead, as generally stated in the literature, of retarding. The fact that this acceleration was found to be independent of the pH value of the carbon suggests that the carbon rubber reinforcement “reaction” and (physical) vulcanization may be related phenomena. 2. When colloidal carbon is used, as in tire treads, in conjunction with other accelerators, disturbances occur due to the selective adsorption properties of the carbon colloid. These disturbances, which are greatest with basic organic accelerators, less with acidic organic accelerators, and least with inorganic accelerators such as litharge, have led to the description of colloidal carbons as quick-or-slow-vulcanizing. 3. The best guide to this “rate of vulcanization” characteristic of rubber carbons is their pH value. 4. Adsorption data are given for cobalt, manganese, lead and zinc soaps, and vary widely for different colloidal carbons. This variation as to the zinc requirements was confirmed by a rubber compounding series. Thus each carbon, depending on its pH and particle size, presents an individual problem in adsorptive requirements, involving fat acid, zinc oxide and accelerator, which should be adjusted in this order. 5. For use with basic accelerators, e.g., D.P.G., colloidal carbons of maximum surface (which involves high fat acid additions with resultant interference with the accelerator) or carbons with low pH (which requires high soluble zinc and therefore high fat acid) are not recommended. Low pH carbons tend to disturb the alkalinity essential to best results, and to adsorb the accelerator. 6. With acid accelerators, e.g., mercaptobenzthiazole, the finer colloidal carbons of moderate to low pH may safely be used. The higher fat acid dosage (soluble zinc) which these carbons require can be freely supplied, since it does not deactivate the accelerator.
The Behavior of Rubber at Low Temperatures
Authors: Sagajłło M. , BobiŃska J. , Saganowski H. 
Published: February 2011

Abstract
(1) Raw rubber, smoked sheet as well as crepe, freezes to a high degree at low temperatures. The difference between the freezing at −10° and −60° C. is comparatively small at initial elongations of 300 and 400%. With smaller initial elongations there is a greater difference in degree of freezing at temperatures of − 10° and −60° C. A complete loss of the elastic properties of the rubber takes place at −70° C. (2) Previous heating of raw rubber, even at a temperature of 140° C, has no effect on its freezing-resistance. (3) The susceptibility of rubber to freezing increases with increase of the elongation, this effect being strongly marked above an elongation of 200%. (4) An increase in the vulcanization temperature, and therefore a shortening of the vulcanizing time, has only an insignificant effect on the freezing-resistance of rubber compounds. (5) The freezing effect increases as the temperature is lowered. (6) An entire loss of the elastic properties of vulcanized rubber takes place for the lower initial elongations at a temperature of —70° C; for higher elongations; however, they are still retanied at this temperature in a very small degree. (7) “Pure” rubber compounds have a much greater resistance to freezing than loaded ones. (8) The minimum susceptibility to freezing for loaded compounds is obtained with those that are slightly overvulcanized. At the higher elongations this minimum is distinctly shifted into the region of overvulcanization. (9) Softeners have in general no effect in reducing susceptibility to freezing. (10) The use of phenyl-β-naphthylamine has no effect on the susceptibility to freezing. (11) The aging of rubber, even when producing 40% of loss of tensile product, has no effect in lowering its resistance to freezing either at −10° or −60° C. and at initial elongations of from 100 to 400%. On the other hand, the resistance to freezing of aged samples is less at temperatures of −40° and −50° C. with initial elongations of 100 to 200% ; at an initial elongation of 300% they show almost no change in relation to unaged samples, while at an elongation of 400% they show a distinct increase in resistance to freezing. (12) Airplane and balloon shock-absorbers of “pure” rubber compounds possess, within the limits of their elongation during use, even at a temperature of — 40° C, quite insignificant susceptibility to freezing. An entire loss of their elastic properties occurs at −70° C. (13) Keeping airplanes in improvised sheds in winter time even at −20° C. has practically no effect on the usefulness of rubber shock-absorbers.