bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protective Action of Antioxidants of the Phenolic Type on the Aging of Natural Rubber
Authors: Yarmolenka N. F. , Novikava E. N. 
Published: February 2011

Abstract
Oxidation of natural rubber in solution by atmospheric oxygen at 100° C in the presence of antioxidants and iron palmitate was studied. On the basis of the relative viscosity of the oxidized rubber solutions, the following conclusions can be drawn. 1. Addition of 1 per cent of certain antioxidants (pyrogallol, pyrocatechol, hydroquinone, 2-naphthol, resorcinol, Neozone D, and Oxynone) retards the oxidation of rubber in solution. However, this quality of antioxidant is not sufficient to stabilize the solution. 2. Comparison of the effectiveness of antioxidants (according to the data of relative viscosity) showed that the best antioxidant is pyrogallol, followed by pyrocatechol, hydroquinone, and Oxynone. The weakest are Neozone D and especially resorcinol. 3. Pyrogallol A, which is not shown in the table, does not protect a 1 per cent rubber solution from deterioration, showing a relative viscosity in solution of 4.08 at the beginning of the experiment and 1.40 after 7 hours, which is equal to that of the unprotected rubber solution. 4. The cresol and xylenol fractions of peat phenols were also used as antioxidants. The addition of 1 per cent of peat fractions to a rubber solution retards the drop in relative viscosity of oxidized solutions, but less than does the standard antioxidant, Neozone D. 5. The structure viscosity of solutions prepared from natural-rubber films which were stored 400 days, both with and without antioxidants, was measured. 6. Antioxidants of the phenol type protect rubber during storage in the form of films in darkness in air; in this case the best antioxidant is pyrogallol, and the next best pyrocatechol. 2-Naphthol is more active than hydroquinone. 7. When rubber is stored for a long time in air in darkness in the presence of certain antioxidants of the phenol type, its solubility decreases considerably; this shows the polymerizing action of some phenols on rubber. 8. Pyrogallol has a particularly strong polymerizing effect on rubber films. After 40 days of storage in air, these films dissolve in benzene in 25–30 days; if they are stored longer, their solubility is still less.
Mastication of Rubber. IV. Polymerization of Vinyl Monomers by the Cold Mastication of Rubber
Authors: Angier D. J. , Watson W. F. 
Published: February 2011

Abstract
The rupture of natural and synthetic rubber molecules into free radicals by the shear imposed during cold mastication under nitrogen initiates the polymerization of monomers incorporated in the rubber. Experimental results on the polymerization of a range of monomers is reported. The polymer formed is mainly attached to the rubber, forming with it either a soluble interpolymer or a two-component gel depending on the monomer used. Results on the co-polymerization of two monomers are also presented and interpreted.
Mechanical Method of Determination of the Vitrification Temperature of Rubberlike Polymers
Authors: Marei A. I. 
Published: February 2011

Abstract
1. A mechanical method has been developed for the determination of the vitrification temperature of rubberlike polymers, based on measurement of the compression deformation of polymer samples in the vitrification temperature region under a constant stress. 2. An apparatus for the determination of the vitrification temperature of polymers by the mechanical method is described. 3. The vitrification temperatures of a series of polymers have been determined. The agreement of results of the determination of the vitrification temperature of the polymers by mechanical and by other methods is shown.
Thermodynamics of Crystallization in High Polymers. Gutta-Percha
Authors: Mandelkern L. , Quinn F. A. , Roberts D. E. 
Published: February 2011

Abstract
The melting temperatures of two of the crystalline modifications of gutta-percha and their mixtures with either methyl oleate or tetradecane as diluent were determined by x-ray diffraction and dilatometric methods. It was found that the melting temperatures of the two forms in the pure polymer were 64 and 74°, respectively. From these studies the heat of fusion per repeating unit of the high melting form was deduced to be 3070 ± 250 cal./mole, while the heat of fusion for the low melting modification was found to be about one-half to three-fourths this value. An analysis indicates the low melting form is a metastable one. The heats and entropies of fusion of each of the forms of gutta-percha are appreciably greater than those of the monomorphic as-hydro-carbon, natural rubber. The difference in the entropies of fusion of the two polymers persists even when allowance is made for the significant contribution of the volume change accompanying fusion.
Viscoelastic Behavior of Polyisobutylene under Constant Rates of Elongation
Authors: Smith Thor L. 
Published: February 2011

Abstract
A variety of methods has been used to study the viscoelastic properties of polymeric materials. These methods include the response to sinusoidal stress (dynamic measurements), stress relaxation, and creep under constant load and constant stress. The present investigation was made to determine whether or not the viscoelastic properties of rubberlike materials over an extended time scale could be obtained from stress-strain curves measured at different strain rates and temperatures. Polyisobutylene of high molecular weight was selected for study, since its viscoelastic properties have been investigated extensively in a cooperative program sponsored by the National Bureau of Standards. From the data obtained, Marvin has derived the distribution functions of relaxation and of retardation times over a time scale of 10−10 to 107 sec. These functions show quantitatively a change in properties from liquidlike to rubberlike to glasslike with decreasing time scale. The equilibrium stress-strain curves for lightly crosslinked rubber and other elastomers are closely linear for elongations up to 100 per cent. The non-equilibrium (viscoelastic) stress-strain curves for similar and noncrosslinked elastomers might be expected to be linear viscoelastic, as a first approximation, at temperatures above the glass transition, provided the strain and the strain rate are not excessively large. Nonlinear viscoelastic effects are usually pronounced for materials in their glasslike state and at large strains.
Radiation Stability of Elastomers
Authors: Bopp C. D. , Sisman O. 
Published: February 2011

Abstract
Ordinary elasticity, high elasticity, and viscous flow are the mechanisms of deformation of solid polymers. Qualitatively, the effect of radiation on the mechanical properties of polymers can be described by considering the effect of crosslinking and cleavage on these mechanisms. Crosslinking tends to impede viscous flow. The equilibrium value of Young's modulus for high elasticity is directly proportional to the concentration of crosslinks, but for ordinary elasticity the sensitivity of Young's modulus is less for more rigid materials. Cleavage reduces the yield stress for viscous flow, and decreases the equilibrium value of Young's modulus for high elasticity. Young's modulus for ordinary elasticity is again insensitive for the more rigid materials. The changes in the mechanical properties of irradiated elastomers depend on the rates of crosslinking and cleavage. These rates are governed both by the polymer's chemical structure and by the strength of the van der Waals forces. For uncrosslinked polymers, the change of Young's modulus is a measure of the crosslinking rate in the case of less rigid materials. Sensitivity to chain cleavage has been correlated with chemical structure for the materials studied.
Rate of Adsorption of High Polymers on Carbon Black in Relation to Their Molecular Weight
Authors: Yurzhenko A. I. , Maleev I. I. 
Published: February 2011

Abstract
The nature and rate of adsorption of high-molecular substances on carbon black is of interest in a number of instances, particularly in the development of adsorption methods of fractionation of high-molecular substances, but also in the use of carbon black as a filler for rubber ; the number of papers on the adsorption of high-molecular compounds is small. The effect of the molecular weight of different polymers on the rate of adsorption of high-molecular substances from their dilute solutions at C=0.1–0.25 per cent was studied in this work. Samples of polyisoprene, polystyrene, emulsion polymerization at a temperature of +5° and +50°, and also a plant sample of SKS-30 rubber, were the objects of the investigation. Moreover, a series of polystyrene fractions was obtained by the method of fractional precipitation from methyl ethyl ketone and butyl acetate, using methanol as the precipitant. For all the polymers and their fractions the characteristic viscosity was determined, from which the molecular weight value of the polymer was determined. Carbon black of the Ukhtinsky and Dashavsky factories was used as the adsorbent, the specific surface of which was determined by the adsorption of acetic acid from a benzene solution.
Surface Treatment of Hydrated Silica Pigments for Reinforcement of Rubber Stocks
Authors: Stearns R. S. , Johnson B. L. 
Published: February 2011

Abstract
Many finely divided solids have been added to elastomers to effect reinforcement of the cured stocks. It is generally agreed that the more finely divided the solid and the greater the degree of physical adhesion (wetting) between the surface of the filler and the polymer chains, the greater will be the general overall reinforcing effect. However, recent work on the mechanism of reinforcement has indicated that an important, if not limiting, property of the filler, in at least modulus reinforcement, is the immobilization of polymer segments on the solid surface. The immobilization is effected by the formation of strong chemisorptive bonds, if not covalent bonds, between the polymer and the filler. The application of this concept to carbon blacks has been discussed in detail by the authors, and similar conclusions have been reached by Blanchard and Parkinson and by Barton, Smallwood, and Ganzhorn. Up to the present time carbon blacks are unique as reinforcing agents in Hevea and GR-S type polymers. The numerous inorganic fillers which have been studied are generally inferior to the carbon blacks in one or more respects. The rubber chemist and technologist is chiefly interested in such properties as modulus, tensile strength, abrasion resistance, and resilience of the compounded stock. Tensile strength and resilience as commonly measured are primarily a function of the extent of surface, the particle-size distribution, and the degree of dispersion of the added pigment or filler. The chemical nature of the solid surface appears to be of secondary importance. Abrasion resistance is a difficult quantity to measure, especially in the laboratory. Therefore, in studying the mechanism of reinforcement and the reinforcing effect of different types of fillers, measurements have been confined to an evaluation of the so-called “equilibrium modulus”, from which an apparent work of retraction may be calculated. It has been found that the work of retraction is highly sensitive to changes in the chemical nature of the solid surface and the results may be interpreted in terms of the kinetic theory of elasticity.
Reaction of Ozone with Natural Hevea and Acrylonitrile-Butadiene Rubbers
Authors: Kendall F. H. , Mann J. 
Published: February 2011

Abstract
The cracking of rubber vulcanizates when exposed to the atmosphere in a state of stress is a well-known phenomenon which has been studied extensively. A comprehensive review of the literature on this subject has been published by Newton. Following the lines of earlier work Newton showed conclusively that the cracking is produced by traces of ozone present in the atmosphere. The simultaneous presence of both stress and ozone is required for cracking to occur and the cracks that form are oriented with their lengths perpendicular to the direction of the stress. It has been reported, however, that similar cracking is produced when stretched rubber is exposed to free radicals produced by the thermal breakdown of organic peroxides. Unstretched vulcanizates do not crack when exposed to ozone, nor do they crack when stretched after exposure to ozone. Apart from the frosting effect described by Tuley, which is stated to require the presence of moisture and which may require the presence of small stresses, there seems to be no record in the literature of a visible effect being produced by the action of ozone on unstretched vulcanizates. The effect of ozone on unstretched vulcanizates has been investigated more completely and the results are reported in the present paper. Little is known of the mechanism of the reactions that lead to cracking of vulcanizates and this paper describes experiments designed to throw some light on this. The products of the reaction between ozone and solid rubber have been investigated by means of infrared spectroscopy. Allison and Stanley have previously described the infrared spectra of products formed from solutions of Hevea and various synthetic rubbers and Salomon and van der Schee have recently reported changes which occur in the infrared spectrum of a film of Hevea rubber when exposed to ozonized air.
Urethan Rubber from a Polyether Glycol. Factors Influencing Processability
Authors: Rugg J. S. , Scott G. W. 
Published: February 2011

Abstract
Adiprene-B urethan rubber is a high-viscosity thermoplastic elastomer that can be compounded and otherwise processed on conventional rubber manufacturing equipment. There are fundamental differences between Adiprene-B and the more common elastomers in processing which must be taken into consideration. 1. Processing temperatures should be less than 121° C to ensure smooth plastic flow and reduce the rate of scorching. 2. Processing temperature is proportional to Mooney viscosity, and both can be reduced by the use of plasticizers. 3. Moisture increases the rate of scorch, and it should be held to a minimum through all phases of processing. 4. Since stocks containing Adiprene-B increase in viscosity during storage, close scheduling of operations will ensure the maximum processable life.
2-Methyl-5-Vinylpyridine Elastomers in Oil-Resistant Service
Authors: Svetlik J. F. , Railsback H. E. , Cooper W. T. 
Published: February 2011

Abstract
Butadiene-MVP copolymers and butadiene-acrylonitrile-MVP terpolymers are a new class of rubbers which can be rendered oil-resistant by reaction with organic halogen compounds during vulcanization. The rubbers respond normally to reinforcement by carbon black and are highly reinforced by mineral fillers such as clay. Oil resistance depends on MVP content of copolymers and MVP and acrylonitrile content of terpolymers. The type and quantity of quaternizing agent also regulate the properties and oil resistance of the vulcanizates. Excellent performance of the experimental rubbers was demonstrated after immersion in ketones, amyl alcohol, ethyleneglycol, acid, caustic soda, a 70/30 2,2,4-trimethylpentane-toluene mixture, and ester solvents. The terpolymers offer better resistance to aromatic hydrocarbons. The experimental rubbers are also superior to the butadiene-acrylonitrile control compounds in contact with hot diester lubricants, giving much higher tensile strength after exposure for 72 hours at 300° F or 48 hours at 158° F. The MVP-containing rubbers possess excellent resistance to flex crack growth. They are also considerably better than the controls in resistance to blowout under severe conditions of rapid cyclic deformation under heavy load at elevated temperatures.
Observations on the Physical Aspects of Resistance to Skidding on Dry Roads and Particularly on Wet Roads
Authors: Knauerhase K. 
Published: February 2011

Abstract
To ensure safety from skidding, attention has up to now been devoted to building rough surface roads, to the development of the proper vehicle construction with respect to this feature, and to the factor most directly involved, the tires. Special attention has been directed in connection with this latter phase to a much more open tread patterning and to the effect of decreasing tire inflation, both of which affect the life of the tire adversely. These steps neglected to take advantage of the physical effect of adhesion, which, without lowering the durability, now makes possible an enhanced contribution to the cohesive friction by the profile grooves which are of necessity retained to keep the weight down. The goal is, therefore, to provide the smooth surfaces of the tread pattern that come in contact with the road with the greatest possible physical gripping power, or adhesion. After illustrating the interfacial magnitudes with the help of a vector diagram, we shall survey the laws of boundary surface adhesion. Here the great influence of the liquid involved in wet friction becomes clear and the particularly favorable interfacial tension property of water can be assessed. Since skidding can occur only at the interfaces : rubber-water, or water-road, the requirement is as follows : both the greatest possible wetting power between rubber and water, and also between water and road surface, that is, hydrophilic properties in the rubber and hydrophilic road surfaces, in order to reduce the danger of skidding. Good insurance against skidding requires hydrophilic rubber and a hydrophilic road surface, for a tire that has been developed to be nonskidding holds on a hydrophilic road surface and skids on a hydrophobic road surface. A hydrophobic tire, on the other hand, skids on any wet road. Although considerable advances have been made with respect to safety from skidding since rubber tires were first developed for motor vehicles, with increase of speeds this problem demands our attention to a greater and greater degree. Safety from skidding can result only from the combined efforts of road and car builders, tire makers, and the chemists and physicists of all three groups.
Tire Wear and Fuel Consumption
Authors: de Decker H. C. J. , Van Amerongen G. J. , Benders J. F. 
Published: February 2011

Abstract
In order to survey the economics for a given country of driving with cold GR-S and natural-rubber tires, we proceeded as follows. With the usual average life of a tire as a starting point, the difference in life was calculated for the two types of rubber on the basis of relative wear resistance measurements. Based on the price of the tire this difference at each temperature is expressed in terms of money. There is obtained in this way, therefore, for the country selected, a curve showing price difference vs. temperature. This curve has to be further corrected because of the greater fuel consumption when the driving is done with cold GR-S tires. Even with equal tire life, it is certainly an advantage to save some fuel. Since our observations on fuel consumption showed no dependence on temperature, this correction only produces a parallel displacement of the curve of price difference vs. temperature. As an example, the resulting curve for West Germany is given in Figure 7 (lower diagram). With the aid of this curve every car driver in West Germany can calculate for himself what is the advantage or disadvantage of natural-rubber tires. For this he needs only to know how many kilometers he has gone at the different temperatures. The upper half of Figure 7 gives a view of the distribution of kilometer performance (mileage) of all private cars in West Germany. The percentage of the tire mileage at the different temperatures is given. In deriving these results, use was made of some statistical data on the traffic density in different months of the year. These data were from the Central Bureau voor de Statistiek in the Hague. Also the meteorological mean temperature values for definite hours of the day and months of the year were taken into account. The conclusion for West Germany is that, on the average, there is a distinct advantage in driving with natural-rubber tires. Conclusions for other countries can be drawn in a similar manner. They are given in very brief form in Figure 8. Surprisingly enough Figure 8 shows that GR-S is advantageous only in a very warm, i.e., tropical, climate. In all other countries, natural rubber shows more or less advantage. An estimate by J. C. Gerritsen, to whom we also are indebted for most of the preceding calculations, shows that over 70 per cent of the motor vehicles in the world can run more economically on natural-rubber tires.
The Enzymic Synthesis of Rubber
Authors: Teas Howard J. , Bandurski Robert S. 
Published: February 2011

Abstract
Studies of the mechanism of biosynthesis of rubber in seedlings and cultured tissues of guayule have established that the carbon of the isoprenoid chain can be derived exclusively from acetate, and flax enzyme preparations have indicated that the branched chain acids, β-methyl crotonic acid and β-methyl-β- hydroxyglutaric acid are probably intermediates in the formation of the basic isoprenoid unit. However, the requirement for intact plants or tissue cultures has made detailed studies of the biosynthesis of rubber difficult. We have now observed that incubation of C14-labelled acetate results in the incorporation of radioactivity into rubber.
Possible Methods of Recharging the Surfaces of Particles of Latexes Stabilized with Soaps
Authors: Voyutskii˘ S. S. , Panich R. M. , Kalyanova K. A. 
Published: February 2011

Abstract
1. It is shown that the surfaces of particles of a synthetic latex stabilized with soap can be recharged by acidification or by the addition of an aluminum salt. 2. It is established that a necessary condition for this recharging is a low-solids concentration in the latex, which makes it possible for the particles to be recharged without the formation of any considerable amount of coagulum. 3. The opinion is expressed that recharging by acidification occurs through the adsorption of positively charged hydrogen ions by the particles of the latex; recharging by the addition of aluminum salts is due to the formation of an amphoteric aluminum hydroxide which is adsorbed by the surfaces of the particles.
Effect of Storage Conditions on the Properties of Latex. I.
Authors: Collier H. M. 
Published: February 2011

Abstract
Working with ammonia-preserved natural-rubber latex, concentrated by centrifuging, the author shows that the slight fall in mechanical stability associated with the shipment of bulk supplies of latex can be explained by the fact that, during shipment, latex does not have access to the oxygen of the air. The mechanical stability of samples taken at the time of shipment increased in value when there was an appreciable air-space in the storage bottle, but fell when the bottle was full and air was excluded. These differences were accentuated when air was replaced by oxygen and was then possible to find marked differences not only in mechanical stability time but also in the volatile fat acid content of the latexes. The increase of volatile fat acid content of the samples stored in the absence of air was much greater than in the sample stored in the presence of oxygen. The fall of mechanical stability in the absence of air is ascribed to the formation of increasing quantities of salts, such as ammonium acetate. In the presence of oxygen, the rate of formation of salts of this type is very much less, and at the same time other changes take place which lead to a marked increase of mechanical stability.