bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tire Abrasion at Different Temperatures
Authors: van Amerongen G. J. , Benders J. F. , de Decker H. C. J. 
Published: February 2011

Abstract
The relative abrasion resistance of tire treads of various types was determined by relatively short but statistically reliable standard tests, with automobiles driven on streets. It has been found earlier that this relative abrasion resistance is a function of the ambient air temperature, and that at medium and lower temperatures, natural rubber treads show better resistance to abrasion than do treads made of SBR. In the present work, it is shown that it is possible to establish the absolute abrasion of a tire and also its dependence on temperature. It appears that the dependence on temperature of the abrasion for SBR is markedly less than for natural rubber. Different carbon blacks show different degrees of dependence on temperature for the abrasion of the compounds. This temperature dependence of abrasion can be reduced for natural rubber by oil extension.
Infrared Study of Some Structural Changes in Natural Rubber during Vulcanization
Authors: Linnig Frederic J. , Stewart James E. 
Published: February 2011

Abstract
A knowledge of the structure of vulcanized rubber is essential to the interpretation of vulcanization and oxidation studies and the physical properties of the material. In the present work an infrared study has been made of structures resulting from a number of different methods of vulcanization. Sulfur vulcanizates show the presence of a shifted double bond, originally observed by Sheppard and Sutherland. The presence of conjugated double bonds is also indicated. Accelerators such as tetramethylthiuram disulfide and zinc dibutyl dithiocarbamate increase the rate of the double-bond shift and reduce the amount of conjugated double bonds. Neither the double-bond shift nor conjugation is observed as a result of vulcanization with tetramethylthiuram disulfide alone, hydrogen sulfide and sulfur dioxide (Peachey process), a peroxide, or gamma rays. These result in a possible decrease in carbonyl structures, and in the case of the last three, possible increased absorption due to OH and ionized carboxyl groups. Apparently, the double-bond shift and conjugation are primarily phenomena related to the use of elemental sulfur. The other vulcanization systems studied evidently involve different mechanisms. An implication of the present work is that there may be a relationship between the reported ease of oxidation of sulfur vulcanizates, accelerated vulcanizates, and sulfurless vulcanizates (tetramethylthiuram disulfide alone), which decreases in the order named, and the probable amount of conjugation in the compound, which decreases in the same order.
Changes in Polysulfide Chain Length in Sulfur Structures of Vulcanizates by Light
Authors: Postovskaya A. F. , Salimov M. A. , Kuzminskiĭ A. S. 
Published: February 2011

Abstract
In previous work we showed that sulfur vulcanizates of polybutadiene rubber (polysulfide and thiuram vulcanizates), which differ in their type of crosslinks, also differ in their stability to light. The best light stability is shown by a polysulfide vulcanizate. The action of ultraviolet light in this case is accompanied by decomposition of sulfur bonds with the formation of a type of free sulfur which, in contrast to elemental sulfur, does not take part in photovulcanization processes, i.e., remains “inactive”. Just what the nature of this inactive sulfur is, and the change in length of the polysulfide chains in the sulfur structures of the above-mentioned vulcanizates under the action of light, had not yet been established. Hence it was impossible to give a well-defined answer to the highly important question of why a polysulfide vulcanizate has greater stability to light than a thiuram vulcanizate. The present work is devoted to a study of this question. Although the study of the types of sulfur bonds in vulcanizates is of considerable importance, no reliable methods for their determination are given in the literature. Ascertaining the nature of the bonds in a vulcanizate by chemical methods involves great difficulties because of the impossibility of separating out the sulfur structures with different polysulfide chain lengths, as well as identical sulfur structures combined with the polymer in varying forms.
The Effect of Swelling on the Strength of Vulcanizates
Authors: Dogadkin B. A. , Fedyukin D. L. , Gul V. E. 
Published: February 2011

Abstract
1. It is shown that, in addition to the previously described steady decrease of tensile strength of vulcanizates during swelling, there are cases in which the strength passes through a maximum at low degrees of swelling. 2. Variations of a similar character during swelling are also found for the relative elongation of vulcanizates. 3. Such variations of tensile strength and relative elongation are found when the increase of chain flexibility and the associated increased orientation effect is greater than the effect of weakened intermolecular bonding in the polymer caused by penetration of the solvent molecules into the polymer. 4. A strength maximum may also be found if the swelling agent (softener) is introduced into the rubber composition on rolls before vulcanization.
The Chemistry of Vulcanization. IV. Action of 2-Mercaptobenzothiazole on the Reaction of Diphenylmethane and Sulfur
Authors: Tsurugi Jitsuo , Nakabayashi Takeshige 
Published: February 2011

Abstract
In Part I of this series, the mechanism of the reaction of diphenylmethane (DPM) and sulfur was discussed, and in Part II, a kinetic investigation was carried out. In this paper, the mechanism and kinetics of the reaction involving DPM, sulfur and 2-mercaptobenzothiazole (MBT) will be reported and compared with those of Parts I and II, respectively. Thus the accelerating effect of MBT has been elucidated clearly. DPM which has no olefinic double bonds but which has α-methylenic hydrogen adjacent to aromatic double bonds has been shown to be an excellent model for studying the mechanism of acceleration by the methods of organic chemistry. The significance of DPM as a model of rubber hydrocarbon in the presence of sulfur alone was discussed in Part I. British investigators using olefins such as dihydromyrcene and squalene as models studied the mechanism of acceleration. However, they could not deduce the mechanism so clearly as we in this paper, only because the reaction of olefins with sulfur seemed to be more complex than that of DPM. Investigations on the reaction of DPM, sulfur and accelerators in the presence of either zinc oxide or zinc soap will be reported in other papers of this series.
CIS-1,4 Polyisoprene Prepared with Alkyl Aluminum and Titanium Tetrachloride
Authors: Adams H. E. , Stearns R. S. , Smith W. A. , Binder J. L. 
Published: February 2011

Abstract
By adjustment of the relative amounts of the two components of the catalyst and the temperature of polymerization, cis-1,4 polyisoprene can be produced free from trans-1,4 configuration. Catalysts containing a mole ratio of alkyl aluminum to titanium tetrachloride of 1.0 produce polymers with this configuration at room temperature. At lower temperature of polymerization, somewhat higher ratios are needed to achieve the same result. Solution polymerization was used to control the reaction and obtain a uniform product. It was necessary to use 3 to 5 phm of total catalyst to obtain 100 per cent yield in 4 hours at room temperature. The inherent viscosity of the polymers made under these conditions is low, usually 2.0 to 2.5. However, higher molecular weight polymers are produced at lower polymerization temperature. Compounding studies indicate that vulcanizates of these polymers possess both normal and hot tensile properties comparable to natural rubber. Hysteretic properties of the carbon black vulcanizates of the polymers studied are inferior to those of natural rubber.
Perdeuterio SN Rubber
Authors: Semon W. L. , Craig David , Fowler R. B. , Regenass F. A. , Tucker Harold , Yanko John A. , Shipman J. J. , Belt R. F. 
Published: February 2011

Abstract
The recently reported stereospecific polymerization of isoprene and the availability of D2O has made possible the preparation of synthetic-natural (SN) rubber in which most of the hydrogen atoms are D atoms. Acetone-d6 was prepared from 99.5 per cent D2O and acetone-h6 in the presence of K2CO3. Nine stages were applied. Each required fractionation of acetone from water, and it is estimated that each replaced approximately half of the light hydrogen remaining from the previous stage. Acetylene-d2 was prepared from D2O and calcium carbide. The procedure of Bergmann for the Favorskii˘ reaction of acetylene and acetone to form 2-methyl-3-butyn-2-ol was followed except that in our work perdeuterio reactants were used. The triple bond of the butynol selectively absorbed D2 over the Lindlar catalyst, and the resulting 2-methyl-3-buten-2-ol dehydrated readily over Al2O3 to give isoprene-d8. Standard fractionation techniques were used for the isoprene and for all the intermediates. The isoprene was finally distilled over sodium to remove acetylenes, acetone, and alcohols. The same methods were applied to the corresponding perprotio derivatives. Table I gives the properties of most of the compounds prepared and used in this study.
Ozone Resistance of Natural Rubber Vulcanizates. Part I. Apparatus for Exposure at Low Ozone Concentration
Authors: van Pul B. I. C. F. 
Published: February 2011

Abstract
An apparatus is described for evaluating the cracking resistance of rubber specimens exposed under static or dynamic conditions to ozone concentrations between 5 and 50×10−8 ml/ml of air. Ozone concentration is kept constant automatically however much is destroyed at the walls of the cabinet or at the surfaces of the rubber testpieces. Temperature can be regulated between 20° and 100° C.
Ozone Resistance of Natural Rubber Vulcanizates. Part II. Influence of Fillers and Waxes
Authors: van Pul B. I. C. F. 
Published: February 2011

Abstract
Commerical waxes whose melting points, refractive indexes and numbers of side chains are within the ranges described seem likely to give good ozone protection under static conditions. All waxes lead to worse cracking under dynamic conditions than if none had been included and it is clearly better to use no wax if the rubber is likely to be submitted to intermittent stretching.
Ozone Resistance of Natural Rubber Vulcanizates. Part III. Influence of Accelerators and Antioxidants
Authors: van Pul B. I. C. F. 
Published: February 2011

Abstract
An investigation of the ozone protection given to natural rubber vulcanizates by different accelerators and antioxidants has shown that, of the accelerators investigated, the thiuram derivatives appear to be the best antioxidants, when they are used as vulcanizing agents; of the large number of antioxidants examined. NN′-di-sec-octyl p-phenylene diamine appears to be the best antiozonant. Vulcanizates containing this material showed no cracks after being exposed for 400 hours to an ozone concentration of 25×10−8 ml/ml under static conditions; it was far superior to all other materials examined.
Speed of Mixing Rubber as a Factor in Processing
Authors: Priklonskaya N. V. 
Published: February 2011

Abstract
1. The work conducted confirms the expediency of using fast mixing methods for synthetic rubbers. 2. It is shown that future improvement may be obtained by using one step loading of all ingredients in the mixer, combined with greater pressure on the mixture and faster rotor speed. 3. We recommend the wide introduction, in production, of the two stage mixing process with increased rotor speed in the first stage. 4. In a factory producing two million tires a year, this decreases the investment by 7.5 million rubles and cuts operating expenses by 2 million rubles per year.
Surface Heating by Friction and Abrasion by Thermal Decomposition
Authors: Viehmann W. 
Published: February 2011

Abstract
In this research, an attempt is made at determining the frictional temperatures which may occur in tires under various driving conditions. This is based on phenomenological theories of heat conduction. Since these temperature pulses are to be traced back to heat current pulses which may last in the neighborhood of 10−2 second, the resulting warming will be localized in boundary layers of the order of 10−2 cm. From the estimated values of the temperatures, it is concluded that the abrasion which occurs under normal driving conditions is purely mechanical. Only under extreme conditions, such as in very rapid acceleration, or in case of locked wheels—particularly at what we call “contact bridges” or surface elevations—may we expect high frictional temperatures, which lie far above the decomposition temperature of rubber.
The Organic Nature of Carbon Black Surfaces
Authors: Hallum Jules V. , Drushel Harry V. 
Published: February 2011

Abstract
Evidence is presented for the existence of quinone groups and aromatic hydroxyl groups on the surface of carbon black particles. This evidence is based largely upon polarographic analyses of slurries of carbon blacks. A mechanism for the chemical interaction of carbon blacks with elastomers is proposed on the basis of these functional groups.
Analysis of Accelerators and Antioxidants
Authors: Parker C. A. 
Published: February 2011

Abstract
For many years the identification of accelerators and antioxidants in vulcanized rubbers was attempted by the application of color reactions directly to the solvent extract of the rubber. Unfortunately very few of the reactions were specific for one compound and they were frequently masked by other colored compounds in the extract. The problem is, of course, complicated by the fact that the compounds appearing in the solvent extract from the vulcanized rubber are not necessarily those which are added to the original mix. The accelerators in particular are liable to undergo considerable decomposition during vulcanization. At first sight the ultraviolet absorption spectrum of the extract might be expected to give the necessary information. The ultraviolet absorption spectra of some of the compounds are reasonably characteristic (Figure 1) but in the extract from the rubber the ultraviolet absorption from the other ingredients (e.g., pine tar) is nearly always sufficient to mask that due to the accelerator or antioxidant. It is usually not possible even to identify the presence of a particular compound, let alone determine its concentration. A selective method of separation of these compounds must be applied before the ultraviolet absorption method can be used. Direct identification is however possible in some cases by other methods. For example recent work has shown that certain constituents of a rubber extract can be identified and quantitatively determined by spectrofluorimetry without separation from the other constituents. This very useful technique is of course only applicable to those constituents which fluoresce.
The Use of Radioactive Sulfur in Vulcanization
Authors: Blokh G. A. 
Published: February 2011

Abstract
One of the newest and most promising physical-chemical methods consists of the use of radioactive tracer atoms, particularly in such varying fields of knowledge as research, industry, agriculture, etc. It should not be surprising therefore that these methods are favored in the study of rubber, especially in connection with the very complex vulcanization process. The use of the isotope method introduces new, realistic prospects to the experimental study of vulcanization. These include the interaction of sulfur-containing chemicals, such as accelerators, in mixtures subjected to vulcanization. A study of the interaction of accelerators with vulcanizing agents, based on isotopic exchange, makes possible a determination of the mobility of sulfur atoms at carbon-sulfur bonds and other bonds of organic substances. By the isotope method it is possible to observe the movements of sulfur tracer atoms and of tagged sulfur compounds in the complex and manifold curing process. The mobility of sulfur in various combinations with carbon is directly related to accelerator structure and activity and, consequently, to the synthesis of new accelerator types. It is very important to clarify the question as to whether the mobility of sulfur atoms and the intensity of the isotope exchange can serve as a criterion for accelerated activity in curing. Tracer atoms can be used extensively to solve many technological problems in the rubber industry. This review deals with scientific studies made in the field of tagged sulfur vulcanization.
The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. Part X. The Kinetics of the Reaction of Sulfur with Cyclohexene and Other Olefins
Authors: Ross G. W. 
Published: February 2011

Abstract
As stated in Part VIII, the kinetic studies now reported are complementary to product studies described in Parts VIII and IX in a program of work aimed at elucidating the mechanism of sulfur-olefin interaction at about 140°. Attention has been given mainly to the reaction of sulfur with cyclohexene, because the latter is a relatively good solvent for sulfur, but reactions with 1-methylcyclohexene, oct-1-ene, hept-2-ene, 2-methylpent-2-ene, 2,6-dimethyloct-2-ene, and the 1,5-diene, 2,6-dimethylocta-2,6-diene, have also been examined. The rate of reaction increases until about 20% of the sulfur has reacted and then continues at an almost steady value until nearly all the sulfur is consumed. Further reaction between the product and excess of olefin proceeds at a diminishing rate. Kinetic analysis has been confined mainly to the period of accelerating rate (ra), and the information obtained appears to justify this procedure rather than considering the steady maximum rate (rm).
The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. Part XI. The Mechanism of Interaction of Sulfur with Mono-Olefins and 1,5-Dienes
Authors: Bateman L. , Moore C. G. , Porter M. 
Published: February 2011

Abstract
Believing an alkenyl alkyl polysulfide to be the major product of sulfurmono-olefin interaction at about 140° and the main constituent of the cyclic monosulfide fraction likewise obtained from 2,6-dimethylocta-2,6-diene to bo the thiacyclohex-3-ene (II), Farmer and his coworkers1 advanced the following free-radical chain mechanism for olefinic sulfuration: (see PDF for diagram) In the special case where the sulfurated radical formed in (2) contains one sulfur atom, alternative reactions to (3) and (4) were proposed, viz., capture of a hydrogen atom, followed by polar or radical addition of the alkenethiol to a second double bond, and this was regarded as the main route to the cyclic monosulfides from 1,5-dienes:
The Elasticity of Rubber
Authors: Wood Lawrence A. 
Published: February 2011

Abstract
Rubbers, natural and synthetic, are unique in being highly extensible and in retracting forcibly and quickly to substantially their original dimensions when released. It has been found that the stress-strain curves for extension and compression of most of the simplest vulcanizates of natural rubber and the three most important synthetic rubbers are similar in shape. The relationship is expressed by the equation F/M=(L−1−L−2) exp A(L−L−1) where F is the stress, L the ratio of stretched to unstretched length, and M and A are constants. The constant M depends on the nature of the rubber, the extent of vulcanization, and the time of creep. The constant A has a value of about 0.38. By a study of stress-temperature relations it is found that the most important factor in the retraction of stretched rubber is the tendency of long chain flexible molecules to return to a configuration which is statistically more probable than the one which the stretching has forced them to assume. Calculations of entropy changes arising from stretching can be made from probability considerations, and a strain energy function deduced from the entropy changes. Stresses calculated from the strain energy function agree with those observed in compression but are greater than those observed in extension by almost 50 per cent at L=3. A phenomenological approach shows that the strain energy should be expressible as a function of certain quantities called strain invariants, calculable from the deformations. The simplest behavior is found in the region of compression (L less than 1), where the strain energy is merely the first invariant times a constant calculable from the entropy changes. For values of L between 1.5 and 3 a different constant and an added term involving the second strain invariant are required. The explanation of this behavior in molecular terms is one of the most important current problems of rubber elasticity.
Friction and Abrasion of Rubber
Authors: Schallamach A. 
Published: February 2011

Abstract
Experimental evidence is adduced for the view that rubber friction is similar in character to viscous flow and therefore, in contrast to solid friction, not necessarily accompanied by abrasion. This theory implies that the forces of rubber friction are proportional to the true area of contact. The true area of contact is determined by elastic deformation of the asperities on the rubber surface, with the result that Amontons' law is not obeyed by rubber. The laws of rubber friction are deduced from simple models and satisfactorily confirmed by experiment. Abrasion of rubber is due to mechanical failure under the tractive stresses produced frictionally by the asperities of the track. In this process, certain periodic structures are often created on abraded rubber which have been called “Abrasion Patterns”. Abrasion patterns are found to increase the rate of abrasion; a distinction is therefore made between “Intrinsic Abrasion”, occurring in the absence of patterns, and “Pattern Abrasion”. Both types of abrasion are treated theoretically, and qualitative agreement with the experimental results is obtained. The phenomenon of pattern abrasion has the important consequence that the relative abrasion rating of any two compounds can depend pronouncedly on the conditions of the test.
The Vulcanization of Elastomers. 20. Sulfur Vulcanization Accelerated with Thiuram Compounds. I
Authors: Scheele Walter , Franck Adolf 
Published: February 2011

Abstract
The present paper deals with the results of an orientating, quantitative investigation of sulfur vulcanization accelerated by thiuram disulfide, with tetramethylthiuram disulfide as the representative example. It was found: In the sulfur cure of natural rubber with tetramethylthiuram disulfide at different TMTD:S ratios, the rates of TMTD decrease and dithiocarbamate formation increase with increasing sulfur concentration, the TMTD content being kept constant. The rates practically do not change any further when the compounds contain 6 gram atoms of sulfur per mole of thiuram disulfide. The peak value of dithiocarbamate formation increases with the increase of sulfur concentration and reaches a constant end value of about 90 mole per cent based on the amount of original thiuram disulfide, when the stocks contain 4 gram atoms of sulfur per mole thiuram disulfide. This end value is identical to the end value of dithiocarbamate formation in the reaction of thiuram disulfide with zinc oxide (in the absence of rubber). The crosslinking, as measured by the change of reciprocal equilibrium swelling per time unit is also a reaction whose rate increases with the sulfur concentration to the point where the compounds contain 6 gram atoms of sulfur per mole of thiuram disulfide. The optimum degrees of crosslinking are roughly proportional to the sulfur concentration; at high sulfur levels the vulcanizates tend to revert. As in the pure TMTD vulcanization, the TMTD decrease as well as the dithiocarbamate formation are always first order reactions. The reversion at higher sulfur levels as well as the complicated course of the increase of combined sulfur during vulcanization render all but impossible an accurate determination of the reaction order for the crosslinking at higher sulfur levels. Nevertheless, in vulcanizations with 1 mole TMTD per 1 or 2 gram atoms of sulfur the crosslinking is a first order reaction.