bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Mechanism of Abrasion of Vulcanized Rubber
Authors: Rudakov A. P. , Kuvshinskii˘ E. V. 
Published: February 2011

Abstract
The authors investigated the abrasion of a number of vulcanized rubbers with the sliding of a smooth steel indenter. Abrasion was achieved by repeated action of an indenter, moving reciprocally along one and the same portion of the surface of the rubber. In the surface layer being destroyed the rubber became tacky; the removal of rubber in abrasion took place by the rolling up into “rolls” of the altered (sticky) surface layer. The character of destruction of the rubber in abrasion is affected by the type of the original rubber, and, in some cases, by the presence of oxygen in the atmosphere. The process of abrasion of vulcanizates of natural rubber and SKI is accompanied by perceptible oxidative degradation. Evidently the wear of rubber is linked essentially with the development of mechanochemical degradative processes.
Analysis of Elastomers by Gas Chromatography
Authors: Hulot H. , Lebel P. 
Published: February 2011

Abstract
This study is the last stage in the design of a new analysis method for either pure or mixed elastomers. Such elastomers are polymers which, when brought to high temperatures, are dissociated into their basic constituent monomers (isoprene for natural rubber, isobutylene for butyl rubber, and so on) and other more or less volatile products. The principle of the study consists in analyzing such different fractions with a chromatographic unit which exhibit peaks used to differentiate various polymers according to their relative positions. The main novelty of the method is the elimination of less volatile fractions which are trapped in ice at 0° C, so that only lighter fractions are fed to the chromatograph. In order that the latter may be fully available or ready for analysis, pyrolysis is carried out directly in the carrier gas circuit, in a furnace set-up, instead of in the gas sample feeding system of the chromatographic unit. Pyrolysis made directly in the unit offers several advantages: Very accurate analysis, since all the pyrolyzate is fed to the unit; Very small samples (1–4 mg); Reduced handling.
Heat Resistance of Neoprene Vulcanizates
Authors: Becker R. O. 
Published: February 2011

Abstract
The resistance of neoprene vulcanizates to degradation when exposed to heat is increased markedly by compounding with selected calcium salts in place of magnesium oxide. The preferred material is a product containing 36% calcium oxide prepared by calcining reagent grade calcium carbonate in a laboratory muffle furnace at 1600° F for 30 minutes. Calcium salts of fatty acids containing 18 carbon atoms in the fatty acid portion of the molecule also are effective. The calcium salt of a more highly unsaturated fatty acid is an effective antiozonant. The stress-strain properties and resistance to compression set and swelling in oil are similar for compounds employing calcium salts compared with magnesium oxide. Calcium salts reduce the processing safety of the compounds, and the resistance of the vulcanizates to swelling in water.
Injection Molding of Rubber
Authors: Masson Pierre-Yves 
Published: February 2011

Abstract
We have seen that injection molding of rubber mixtures has now passed beyond the stage of laboratory practice. This forward stride is due to the appearance of new synthetic polymers. Now this technique should become a part of the rubber industry and allow it to be competitive and recover some of the manufactured products which the thermoplastic materials had displaced because of their possibilities for injection. The objective of this conference was to bring the rubber manufacturers up to date on developments and to supply the technical bases for guiding them toward perfecting the manufacturing processes. There still remain many studies to be made, in particular in the field of working out recipes to give the best results, and we believe that many specific problems remain yet to be solved. We hope that the preceding discussion relative to experiments, and the principles we have just described, will provide the necessary orientation for our future work.
Swelling Studies of Filled and Unfilled Vulcanizates
Authors: Butenuth G. 
Published: February 2011

Abstract
Every crosslinked and nonerosslinked polymer shows elastic rubbery properties within some temperature range specific for the material. Within this range it approaches more or less the conditions of ideal rubber elasticity, e.g., the state of unrestricted, coiled molecules without energetic interactions. Noncrosslinked materials flow under the influence of an external force. The centers of gravity of the coils change their relative positions to each other. These materials, therefore, have to be stabilized by introduction of chemical bonds—crosslinking points. At the same time the crosslinking points constitute the end points of the smaller coils between them. The average molecular weight of these coils decreases with increasing crosslinking density. The entropy of the system changes as the average molecular weight between the crosslinking points changes; thus, all properties correlated with the entropy change considerably. for systems fulfilling the theoretical requirements, the correlations between crosslinking density and macroscopic properties like modulus and swelling are well known. The crosslink density can be calculated from macroscopic data. Various deviations from the theoretical correlations will occur in any real system like, for example, sulfur-cured natural rubber. The first purpose of this paper is the discussion of these deviations for nonfilled vulcanizates. Additionally, an attempt will be made to explain the deviations in filled systems.
Failure Criteria for Some Polyurethane Propellants
Authors: Milloway Warren T. , Wiegand James H. 
Published: February 2011

Abstract
Experimental and theoretical studies were made on failure criteria applicable to simple case-bonded hollow cylindrical grains. The minimum strain at break at −75° F for uniaxial tensile test was found to be at least twice the hoop strain at −75° F of a thermally cycled, case-bonded hollow cylinder of propellant when no failures were observed, whereas, when the minimum strain at break was equal to or less than the hoop strain of the cycled cylinder, the grain always cracked. For uniaxial tension, where the rate of elongation and temperature are controlled variables, the failure elongation varies from specimen to specimen and from batch to batch. A study of batch variability of the uniaxial test showed that a test at any test temperature from −40° to 180° F could be used to characterize batch quality. The correlation of breaking strain at different rates and temperatures with the use of the WLF technique on one batch was found to be improved if an additional vertical shift factor was added to account for the lowering of the maximum failure elongation for temperatures below 0° F. However, by using a diagonal shift with rate, a graph of failure elongation versus temperature shows lower variability than does the WLF analysis.
Relation of Mechanical Properties to Solid Rocket Motor Failure
Authors: Bills Kenneth W. , Wiegand James H. 
Published: February 2011

Abstract
Experimental studies of propellant specimen and motor behavior during failure provide insight into the probable mechanisms of failure in a composite propellant system. At low rates and high temperatures, failure results from at least two successive processes: first, a dewetting or breaking of the binder to oxidizer bonds, and second, a tearing in the binder structure initiated at points of stress concentration such as regions of binder-oxidizer dewetting. Stress-strain analysis of a motor shows the potential failure points, and a failure analysis indicates the required mechanical properties to withstand failure. Laboratory testing has given a method of classifying propellant behavior, an estimate of material failure variability, and a method of correlating the uniaxial with biaxial tensile properties and with rate and temperature of test. Uniaxial tensile properties are obtained more conveniently by laboratory measurements, but biaxial properties appear to be related more directly to inner bore grain cracking. Good correlations were demonstrated between motor failures in thermal cycling and the failure properties of the propellant from laboratory tests.
Recent Advances in Mechanical Properties Evaluation of Solid Propellants
Authors: Wiegand James H. 
Published: February 2011

Abstract
Methods of mechanical properties measurement have become more sophisticated as the necessities of nonlinear stress analysis have been appreciated. The linear cases, typical of low temperature failure, have been successfully handled by elastic analysis, but the nonlinear complexities of the higher temperature regimes require analytical correlation of real properties and analytical methods of using such correlations. The wide variability of mechanical properties observed in solid propellants requires that predictions of failure be based on estimates of upper and lower expected limits rather than viewing failure as a point value, as is often done in stress analysis of metallic structures.
Studies on the Kinetics of Vulcanization of Rubber
Authors: Taneja H. L. , Banerjee S. 
Published: February 2011

Abstract
The dependence of the rate of accelerated vulcanization of natural rubber (smoked sheet) on the concentration of mercaptobenzothiazole accelerator has been reported on in this paper. The rate of decrease of free sulfur at the steady state has been found to be proportional to the square root of the initiator concentration expressed as grams/100 grams of rubber. The rate has also been found to be enhanced by the addition of 1% of zinc oxide. Higher amounts of zinc oxide does not lead to a further appreciable increase in the rate.
Estimation, from Swelling, of the Structural Contribution of Chemical Reactions to the Vulcanization of Natural Rubber. Part II. Estimation of Equilibrium Degree of Swelling
Authors: Ellis Bryan , Welding G. N. 
Published: February 2011

Abstract
An investigation has been made of the measurement of degree of swelling of vulcanizates and the estimation of υτ, the volume fraction of polymer in a vulcanizate swollen to equilibrium. Methods have been established for dealing with a volatile swelling liquid, allowing for small percentages of nonpolymer in the vulcanizates, testing for diffusion equilibrium and correcting for swelling increment. The resulting values of υτ are suitable for use as described in the preceding Part I.
Studies of Ozone Attack of Vulcanizates in a Closed System
Authors: McCool John C. 
Published: February 2011

Abstract
1. A new procedure for studying the attack of vulcanizates by ozone in a closed system has been devised which permits measuremont of ozone consumption as a function of strain, environments, and compounding aspects. 2. Extent of attack is best determined by cut growth measurements and by photographic records of the samples after test. 3. The accelerated attack by ozone observed at reduced total pressure reported now as a new observation appears to reflect the probability of ozone collisions with olefinic bonds which are part of uncoiled or “strained” polymer segments. Retraction of the chain ends formed by cleavage due to elastic forces present determines the rate at which sub-surface networks become accessible to ozone. 4. Ozone consumption per se does not predict the resistance of a vulcanizate to ozone attack, nor does it correlate with the presence of antioxidants or antiozonants. 5. Environmental conditioning of vulcanizates has a definite effect on their ozone resistance, indicative of the role which surface films have on protection. 6. The effects of antiozonants appear to represent a protective principle involving their reaction with the ozone cleavage products of olefinic bonds. 7. No evidence has been found to indicate that ozone attack of vulcanizates proceeds through a chain reaction involving oxygen.
Thermodynamics of Elasticity of Natural Rubber
Authors: Allen Geoffrey , Bianchi Umberto , Price Colin 
Published: February 2011

Abstract
The thermoelasticity of a natural rubber strip held in simple elongation at constant volume has been studied experimentally. From the direct measurement of (∂f/∂T)L,V the energetic and entropic contributions to the total elastic force have been evaluated. The results agree with indirect estimates based on data obtained at constant pressure, the energetic contribution to the elastic force being some 20%. The dilation coefficient for natural rubber has also been obtained in a subsidiary experiment.
Vulcanization. Part II. Fate of Curing System during Sulfur Curing of Nr Accelerated by MBT Derivatives and Activated by Zinc Stearate
Authors: Campbell R. H. , Wise R. W. 
Published: February 2011

Abstract
As discussed in Part I it was generally believed that during the sulfur vulcanization of rubber, important vulcanization intermediates are formed as a result of reactions between components of the various curing systems, e.g., sulfur, accelerator, zinc oxide and elastomer. A variety of reaction products have been postulated, however, actual supporting evidence for most of these postulations is limited. This is not surprising considering that the complexity of the system makes the identification and quantitative determination of these intermediates by conventional analytical techniques difficult. Part I of this paper described some analytical methods and the application of procedures for determining the fate of the curing system throughout the vulcanization of natural rubber in the presence of sulfur and various benzothiazole type accelerators. This study confirmed that important vulcanization intermediates are formed during the vulcanization process and that they play decisive roles in delay action acceleration. However, in most practical cases zinc oxide and stearate are also required to obtain satisfactory vulcanization and curing characteristics. It was therefore desirable to extend the studies to curing systems which include zinc and stearate ion.
Ultraviolet Absorption Spectroscopy in the Study of Vulcanization
Authors: Huke D. W. , Kendall C. E. 
Published: February 2011

Abstract
Practically all UV absorption spectroscopy is done in solution, and examples of its use in examination of neat (one component) solid materials are relatively few. In the IR on the other hand, the examination of thin films and microtomed sections of elastomers and plastics is a normal procedure. The reasons for this are fairly obvious: scatter by optically imperfect films is much more serious in the UV, many polymers give no specific UV absorption, and those that do absorb often give such intense absorption that impracticably thin films would be required. The main value of UV is in examination of trace amounts of UV-absorbing materials in those polymers which are more or less transparent, the best example being the study of crosslinking of elastomers. This work cannot be done in solution because the cross-linked polymers are insoluble in all solvents. A great deal of the work on the chemistry of vulcanization has therefore been done on model compounds of low molecular weight, most notably at the Natural Rubber Producers' Research Association. Although the use of model olefins has yielded valuable information, investigations on polymers are required because the different conditions, particularly in steric factors, may appreciably alter the balance of reactions.
Age Resisters for Rubber. A General Study
Authors: Kempermann T. 
Published: February 2011

Abstract
Many scientific and technical problems arise from the phenomenon of aging in elastomers. Aging is not a simple problem, since, in the first place, different elastomers give rise to different degradation effects, and secondly, one and the same elastomer may age in a variety of ways. These may include processes—such as autoxidation and fatigue—which entail complete disintegration of rubber articles under prolonged stress; other processes, however, may certainly impair properties, but under permanent environmental stress a stationary state is reached in which only slight destruction exists. “Frosting” and “crazing” are examples of these effects. Certain aging processes occur exclusively on the surface of an elastomer which is unaffected internally, e.g., ozone cracking. Others, however, arise preferentially within the article concerned, e.g., attrition effects. Finally, there are degradation effects, such as autoxidation which progress uniformly and are not localized. Following these preliminary remarks we shall now proceed to briefly examine the principal aging effects. This paper deals with measures to combat such effects by means of anti-agers or, in North America, simply “age resisters”.
Cement Mortars Modified by SB Latexes with Variable Bound Styrene
Authors: Ōhama Y. , Ibe H. , Mine H. , Kato K. 
Published: February 2011

Abstract
Recently, the practical research and development of SB latex for a cement modifier have taken place and the cement mortars so modified are used in the field of building or civil engineering. The physical and chemical properties of SB latex-modified mortars have already been reported, but the effects of various polymerization conditions for latex synthesis on properties of SB latex-modified mortars have hardly been noticed. The authors discuss the effects of polymerization conditions, in particular, styrene/butadiene monomer ratio on physical properties of SB latex-modified mortar and conclude that the physical properties such as strength, drying shrinkage, adhesion, abrasion and shock resistance, etc., of SB latex-modified mortars are affected more intensely by the variation of bound styrene contents than by the rubber-cement ratios.
Reinforcement of Butyl with Carbon Black. I. Effect of Oxidized Blacks on Stress-Strain Properties and Bound Rubber
Authors: Gessler A. M. 
Published: February 2011

Abstract
The increased reinforcing capacity of oxidized blacks in butyl is illustrated, and the results are discussed in terms of the relationships which exist between polymer and black. Oxygen functionality on the black, it is shown, is the critical factor controlling the extent to which butyl is reinforced by the black. The lesser effects of decreased aggregate structure in the black are also demonstrated. These results are obtained using blacks which, though similar to attrited blacks, derive both their physical and chemical properties without the use of comminution. A much more unambiguous approach to the questions of black structure and oxygen content is therefore provided. In butyl, the unique sensitivity of the stress-strain curve to reinforcing effects is attributed to low unsaturation in the polymer. This sensitivity is used to qualify the nature of the reinforcement which is obtained. With oxidized blacks, true reinforcement is pictured as a stiffening effect which, starting with the gum vulcanizate, shifts the stress-strain curve without essentially changing its shape. The result is a “reinforced gum” which, it is suggested, derives its physical characteristics through the bonding of carbon black in the rubber network. With untreated black, carbon black is pictured as being enmeshed or entangled in an independently formed rubber network. Changes in the shape of the stress-strain curve are therefore attributed to steric restrictions which this arrangement imposes on the initial movement and subsequent orientation of network chains when the sample is extended.
Improvement of Asphalt by Addition of Rubber and Latex
Authors: Esser H. 
Published: February 2011

Abstract
Since the technical expressions and measurement methods appearing in this article are apt to be unfamiliar to many readers, they will be defined briefly. It is realized that on the one hand a certain eonfusion in concepts exists with respect to the terms bitumen, tar, and asphalt, and on the other, the test methods leave much to be desired, in the opinion of experts in the field. Bitumen differs from tar in its origin, for one thing. Whereas tar is the residue of the distillation of coal, bitumen is understood to be distillation residues derived from petroleum. Bitumens are colloidal systems, one phase of which contains organic substances, dispersed in the second phase, which consists of hydrocarbons having different molecular weights. Asphalt is understood nowadays to be a mixture of bitumen and mineral substances. Such mixtures, when found already combined in nature, are called natural asphalt, asphaltic rock, or crude asphalt. The uses of bitumen in technology and industry are very manifold; mention need be made only of applications for roofing paper and electrical insulations, in construction both below and above ground, for interior, exterior, and underwater coatings, for sealing purposes, and in the rubber industry. Of special importance is the use of bitumen in road construction. The combined use of bitumen and rubber is very old. Pertinent patent applications go back to the year 1843. Large scale experiments with rubber-modified bitumen in the road construction sector have been going on for about 30 years. Important investigations and contributions have been made by Anglo-American and, especially, Dutch scientists. In the addition of rubber to bitumen, the latter undergoes many essential and (for the road engineer) advantageous changes in its properties. Before these properties are taken up individually, a report will be given of the methods of physical investigation employed to test the characteristics of both “pure” bitumen and rubber-modified bitumen. Among the tests intended to characterize the properties of bitumen are those for penetration, softening point, breaking point, flow length, ductility, tenacity, toughness, and elasticity. It was only a few years ago that another method was developed, which provides for a very practical assessment (and one suitable for industrial applications) of the essential characteristics of rubber-modified bitumen. These basic features are useful for putting into proper perspective the unusual improvements which can be realized by the addition of rubber. This new method is known in the literature as the “tenaacity—toughness test. It will be explained later on, in more detail. The various methods can be summarized as follows:
Fibrous Structure in Stretched Crystalline Elastomers
Authors: Walters M. H. 
Published: February 2011

Abstract
Stree-induced crystallinity in elastomers produces a strengthening structure, and tearing the rubber along the axis of extension leaves this structure outlined in the rupture surface. By maintaining the initial elongation, and taking replicas of this torn surface, the morphology of stress crystallinity has been examined in the electron microscope. The crystallites were found to be closely spaced fibers, rounded in section, and oriented in the direction of elongation. The fibers were usually between 100 and 1000 A in diameter, and individual crystallites could be traced for distances of several microns before disappearing beneath the exposed surface. Noncrystallizing polymers showed no structure in the rupture surface. The addition of fine particle fillers had little effect on the structures observed in crystallizing polymers. In amorphous polymers traces of structure were observed, apparently consisting of groups of carbon black particles linked by rubber molecules.
Sol-Gel Analysis to Estimate Chain Scission during Cure. I. Peroxide Vulcanization of Natural Rubber
Authors: Bristow G. M. 
Published: February 2011

Abstract
Sol-gel analysis, that is, the measurement of the fraction of rubber remaining unconnected to the network as a function of the degree of cure, has been used to estimate the extent of chain scission in the vulcanization of natural rubber with dicumyl peroxide at 130° C. For peroxide concentrations in the range 1–5 per cent and masticated rubbers of Mn=0.84−2.67×105 there are only 1–3 sites of scission per 100 crosslinked isoprene units.