bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degradation of Rubber by Chemical Agents in Solution
Authors: Foxley G. H. 
Published: February 2011

Abstract
It is clear that the subject of polymer degradation by chemical agents is an active branch of polymer chemistry. This is reflected in the large number of patents applying to polymer degradation and no attempt has been made to include every appropriate patent. Much of the comparative work is based on equal weights, rather than equal numbers of molecules, so that the true comparisons of the efficiency of peptizers are often difficult. It has been shown that polymer degradation can proceed via several mechanisms all of which involve free radicals and the main points can be summarized as follows :— In solutions at low temperatures the initiatory free radicals come from the added peptizer such as benzoyl peroxide or bis-azoisobutyronitrile. Although oxygen accelerates the reaction, it is not essential, and there is appreciable degradation in the absence of oxygen. Thiols are active only when oxygen is present even at high temperature. This is somewhat surprising, since the rubber radicals produced by thermal scission should be just as active as those produced by mastication and be capable of reaction with thiols, and serves to emphasize the importance of the role of oxygen in peptization by thiols and disulfides. Oxygen is also necessary for degradation by redox systems and in its absence structurizing takes place. The lack of work on triphenyl methane derivatives is somewhat surprising in view of the ease with which they undergo homolysis to give free radicals. However, it is not sufficient to introduce any type of free radical and expect degradation: stabilized free radicals are the best peptizers, unstable radicals can add to olefinic bonds and cause crosslinking rather than chain scission. Squalene has been used as a model compound for the study of the reactions of natural rubber with free radicals in a similar manner to the use of methylcyclohexene as a model compound for oxidation studies. This review forms part of a dissertation submitted in partial fulfillment of the requirements for the London University M.Sc. (External) Examination.
Recent Developments in Synthetic Rubber Latex
Authors: Howland L. H. , Brown R. W. 
Published: February 2011

Abstract
Progress has proceeded at a good rate since the close of the Government Program in the spring of 1955. Improved latexes have been made, and the technology of manufacture and of application has advanced. Also progress has been made in fundamental latex research. Some of the newer latexes representing the more important advances are those involving functonal groups derived from the use of unsaturated monomers such as those containing amino groups and carboxy groups in the polymerization system, those from solid rubbers by the solvent emulsion technique, and those of higher solids content including the agglomerated latexes giving 68 per cent minimum solids at low viscosity. Some of the applications of greatest growth are : 1. Carpet backing involving both sulfur curing and so-called self-curing (noncured) elastomer latexes. The latter obtain strength from polar groups including functional (carboxyl) groups and/or fairly high styrene content. 2. Foam sponge backed carpets. In 1954 it was suggested that synthetic rubber latexes would have a permanent place in our economy. This has now come to pass, and natural latex is decreasing in volume compared to total synthetic rubber latex consumption. It now appears that by forming a latex from cis polyisoprene (synthetic natural rubber) and adding it to our list of latexes, that our country could probably become independent of the natural product.
Fluorine-Containing Elastomers
Authors: Montermoso J. C. 
Published: February 2011

Abstract
Fluoroprene, the first fluorine-containing elastomer, was developed by E. I. du Pont de Nemours … Company and reported by Mochel and others in 1948. However, intensive research to develop specialty rubbers from fluorocarbons was not started until the early 1950's. At the time, there was an urgent military need for fuel and chemical resistant rubbers for service under extremely low temperatures. Consequently, most of the fluorine-containing elastomers were the result of research conducted or sponsored by the Department of Defense. Army experiences in the Aleutians during World War II and in several task force operations in the Arctic regions showed, among others, that fuel hoses became brittle and cracked. Gaskets failed to function. On shipboard, the Navy was experiencing similar difficulties with rubber items. The Air Force, on the other hand, was being plagued with an epidemic of fuel leakage on many of its aircraft. The extraction of the plasticizers from the nitrile rubber compounds and the low temperature of the environment caused shrinkage of the seals and gaskets resulting in leakage of fuels. Obviously, a solution to these problems was to develop new fuel resistant rubbers which would be inherently flexible at extremely low temperatures.
Copolymerization of Butadiene and Isoprene through Use of Complex Organometallic Catalysts
Authors: Bresler L. S. , Dolgoplosk B. A. , Kolechkova M. F. , Kropacheva E. N. 
Published: February 2011

Abstract
Processes were investigated for the copolymerization of butadiene and isoprene, with the catalyst systems: aluminum triisobutyl/TiCl4 and aluminum diisobutyl chloride/cobalt chloride, complexed with ethyl alcohol. From study of the properties of the resulting polymers, and of butadiene/ isoprene homopolymer mixtures, it was established that in the presence of the cited catalysts, genuine copolymers were in fact obtained from the mixtures of isoprene and butadiene. Constants were determined for the copolymerization of butadiene and isoprene, in presence of the indicated catalysts, by tracer techniques.
Accelerated Thermomechanical Testing of Vulcanizates
Authors: Briggs G. J. , Edwards D. C. , Storey E. B. 
Published: February 2011

Abstract
The use of simple mechanical tests, conducted in an environment of rapidly changing temperature, proves to be a valuable approach to the preliminary study of rubber compositions. The differential strain test in particular is a most useful and convenient scanning procedure, allowing the estimation of basic quantities and the assessment of the general physical character of experimental vulcanizates. The test serves to identify types and regions of unusual behavior, which can then be pursued if desired by methods appropriate to the case. Where the careful study of particular questions requires the application of more refined and specialized techniques, these simple mechanical procedures, requiring little time and material, can contribute greatly to intelligent experimental design.
Analytical Chemistry of Plastics. XIX. Analysis of Rubberlike Mixed Polyurethans
Authors: Schröder Elisabeth 
Published: February 2011

Abstract
Polyester urethans, the most important class of rubbery mixed polyurethans, can be recognized by their nitrogen-containing, neutral-to weakly-acid pyrolysis gases in conjunction with their ease of saponification. Also the detection quoted by Swann using p-dimethylaminobenzaldehyde can be recommended for their identification. In view of the multiplicity of possible methods of forming polyester urethans it appears, however, more important from the standpoint of quantitative analysis to provide for identification of the most important components as well as allocation to a definite raw material group. Detection of dicarboxylic acids.—The detection of carboxyl groups by way of hydroxamic acids has already been referred to. This detection, which is always positive for every dicarboxylic acid and is of low specificity, has to be supplemented by special detection methods. Of these we may name:
Flexcracking of Polymers
Authors: Akkerman F. H. D. 
Published: February 2011

Abstract
Accurate measurement of several types of fatigue failure in polymers was obtained with a flexing machine equipped with an automatic camera. The technique is described at length. Observations made include that an antiozonant interferes with crack initiation, that a crack may well start under the surface, and that in the growth of a crack the elastic force is equivalent to the hysteretic force. Several photographs show aspects of crack initiation.
The Use of Rubber Models as a Stress Aid
Authors: Pope A. W. 
Published: February 2011

Abstract
During the design of a new diesel engine crankcase, it was thought that it would be possible to get a measure of the effectiveness of various rib shapes and positions by using a scale rubber model. Silicon rubber (made by I.C.I.) was chosen, as this could be cast easily and would faithfully follow any pattern. As it proved difficult to make a negative pattern of a section of a crankcase, a normal wooden pattern was made and then rubber cast around it. This made a rubber mold (see Figure 1 ), which was used, after coating with a separating agent such as “Vaseline”, to cast a final rubber model. This is shown in Figure 2. Strips of paper were placed between the model and the board (B) to which it was glued so that there was only attachment where there are bolts in the actual engine.
Thermostability of Sulfenamide Accelerators in Tire Compounds
Authors: Kleeman W. , Erben G. 
Published: February 2011

Abstract
The laboratory-type decomposition isotherms plotted by the authors have shown that in all the investigated commercial-type sulfenamide accelerators, dissociation already occurs at 120° C. Within the range of the required mixing times, 140° C can be regarded almost generally as the critical temperature. As shown by technological investigations, at 140° C and higher, there is definitely a marked effect on processing properties, and on the vulcanization behavior of the compounds. The results of the investigation clearly demonstrate, once again, that when compounding temperatures are going to exceed 140° C, it is necessary to mix in the sulfenamide accelerators in a second stage at lower temperatures, preferably below 100° C. Even when the accelerators are incorporated on a mill, immediately after the internal mixer is discharged, a dissociation of the sulfenamide accelerator must be reckoned with if the compound cannot be sufficiently cooled.
The Fraction of Effective Sulfur Crosslinking in SBR Vulcanizates
Authors: Meltzer T. H. , Dermody W. J. , Tobolsky A. V. 
Published: February 2011

Abstract
Shear modulus measurements as a function of temperature have been made for SBR vulcanized with sulfur in amounts between 6 and 34% of the recipe. The shape of the modulus-temperature curves are typical of crosslinked amorphous polymers and there is a consistent displacement of the curves toward higher temperatures as the percentage of sulfur in the mixture is increased. The rubbery plateau modulus also increases with increasing sulfur, and from its magnitude the concentration of crosslinks is computed. The ratio of crosslinks to total sulfur atoms is below 0.20 in all cases. The results lend support to the conclusions of Bateman and of Bloomfield that a high proportion of cyclic structures is formed during sulfur vulcanization.
Evaluation of Crosslinking Coagents in Ethylene-Propylene Rubber
Authors: Lenas L. P. 
Published: February 2011

Abstract
Ethylene-propylene rubber (EPR), a saturated elastomer, is usually vulcanized by a peroxide-sulfur curing system. However, several disadvantages associated with this system—undesirable odor for some applications, narrow curing range, and poor strength obtained with mineral fillers—emphasize the need for other reactive chemicals as crosslinking coagents for EPR. Certain polyfunctional monomers such as ethylene dimethacrylate, and polyfunctional polymers such as 1,2-polybutadiene were promising crosslinking coagents for EPR. When used in place of sulfur, they decrease peroxide requirements of moderately filled EPR compounds. They also impart higher states of cure, improve the cure cycle, and decrease odor. The coagents are much superior to sulfur in mineral-filled EPR compounds where, in addition to increasing the crosslinking efficiency, they also improve the wetting of the filler particles by the rubber. However, in highly loaded (carbon black and oil) EPR formulations, the superiority of the peroxide-coagent system is mainly due to the ability to replace sulfur and, consequently, to improve odor.
A New Type of Tackmeter
Authors: Bussemaker O. K. F. , van Beek W. V. C. 
Published: February 2011

Abstract
A new type of tackmeter is described. Strips of the material to be tested are used for tack measurements. The instrument compresses and separates the strips under conditions which can be arbitrarily selected. The tackmeter is of rugged design for simple handling and ease of operation. The test results are recorded on a chart, enabling easy reading of the results. A description of the tackmeter and the testing procedure is given. The accuracy of the measurement is briefly discussed. Among the factors affecting the measurement are the thickness of the sample, compression conditions and aging of the surface. Some test results obtained with factory-made plies and compounds with varying black loadings are given.
Thermomechanical Characterization of the Molecular Weight of Linear Polymers Exemplified by Natural Rubber
Authors: Teitelbaum B. Ya , Gubanov K. F. 
Published: February 2011

Abstract
In the previous work of Kargin and Slonimskii and that of Kargin and Sogolov who studied the behavior of polymers over a wide range of temperature, it was shown that the shape of thermomechanical curves depends on magnitude of molecular weight of the polymers. As a result of investigation of theory and actual experimental studies in which polyisobutylene was employed, it was demonstrated that molecular weight could be estimated on the basis of thermomechanical properties. This suggested a relationship between the magnitude of molecular weight M found from the thermomechanical curves and that which was determined from glass temperatures Tg and fluid temperatures Tf. For practical use of this relationship, it is necessary to know the magnitude of the segments and two empirical constants. These values can be found by calculation of molecular weights of three different fractions of the polymer. This can be accomplished experimentally by any independent method. Once these magnitudes are determined, it is necessary to find, by means of the thermomechanical curve, the values Tg and Tf, in order to calculate the molecular weight of any sample of the same polymer. Because of the low degree of accuracy of determination of these values, and because of the peculiar differences, the reliability of the calculated molecular weight cannot be great, especially since the equation utilizes the logarithm of the molecular weight figure and not the molecular weight itself. Apparently the graphic solution is simpler than analytical methods: by means of the data of thermomechanical studies for various fractions of known molecular weights it is possible to graph the dependence of M or log Mon Tf−Tg. From what has been said, it is evident that we may use the demonstrated method only for polymers of high elasticity, and furthermore, only for those fractions in which Tf−Tg is greater than zero.
On Testing Rubber
Authors: Juve A. E. 
Published: February 2011

Abstract
Measurements are basic to all natural sciences, in fact some say that science is measurement. Whether it is the measurement of the temperature on the moon or the hysteresis properties of a rubber compound, the measurements are intended to give us accurate data with which to proceed further in our understanding of nature. Measurements and analyses are essential in every stage of rubber science and technology from the synthesis of a new rubber chemical to measurements of performance of some complex product such as a tire in service. The all-pervading role of measurements is frequently not appreciated, but a simple observation which each of us can make will demonstrate this fact. A cursory examination of the slides presented at this and other Division of Rubber Chemistry meetings will show that at least 95% of them contain the results of physical or chemical tests required to demonstrate, illustrate or prove a point the speaker is attempting to make. Furthermore, many of the papers will be concerned solely with a new test method or method of analysis. Although as a compounder my work was only incidentally involved with testing, the subject of testing has been a most absorbing interest of mine and it seemed that a discussion of some aspects of it would be acceptable for this lecture. A rough distinction can be made between those tests involved with the fundamental science of rubber as a primary aim and those involved with the engineering practice of rubber technology, although there is an inevitable overlapping. My concern here will be with the latter group and, in general, with those methods which have been standardized by Committee D-11 of ASTM. My central theme will be that too much testing is done, that many of the methods are inadequate, that many are inadequately understood by the users and inadequate analysis and interpretation are made of the data obtained. In an attempt to brighten the picture a little, I will conclude by discussing some new methods which appear to be decided improvements, both from performance and in being adequate in respect to being easily understood by most users. What I have to say will be somewhat critical of the methods used and sympathetically critical of the people who use them. At the start I should point out that criticism of the methods is not a criticism of Committee D-11 of ASTM. It should be realized that D-11 almost invariably standardizes methods which are fairly widely used in the industry and for which a need for standarization is expressed by the industry. The Committee rarely develops new methods, although it can be said that in the process of standardization, methods are usually improved. One of the more important purposes of standardization is to formulate methods so that different laboratories will obtain reasonably reproducible values without which chaos would result.
Experimental Findings on the Abnormal Freezing Point Depression of Swelled Cured Natural Rubber
Authors: Butenuth G. , Westlinning H. 
Published: February 2011

Abstract
The method of Kuhn and coworkers for the determination of crosslink density for swelled cured rubber was applied to unfilled peroxide- and sulfur-cured samples. Comparison with other methods confirms the new method. Experimental data for a number of filled samples is presented together with the mesh size of the network determined by the method of Kuhn.
Service-Induced Diffusion and Nodule Formation in Rubber Stocks
Authors: Smith R. W. , Black A. L. 
Published: February 2011

Abstract
Diffusion of materials within a rubber compound caused by temperature gradients may cause nucleation and growth of crystals in favorable sites. The rubber may or may not be affected by this process, but if it is affected, a dense area termed a nodule results. Zinc stearate is the prime agent responsible for forming nodules in typical tread compounds. After the formation of a localized concentration of the stearate, crosslinking conditions are favorable and this proceeds with the infusion of sulfur. Conditions favorable to nodule formation are those conditions favoring diffusion, i.e., prime temperature gradients, “soft” compounds, solubility effects and undoubtedly dynamic mechanical stress.
Thermomechanical Studies of Amorphous and Crystalline Polymers
Authors: Sidorovich A. V. , Kuvshinskii E. V. 
Published: February 2011

Abstract
A thermomechanieal study has been made of the softening of crystalline polymers during uniform, uniaxial stretch and also of the effect of the rate of heating upon the softening of amorphous polymers. The effect of the tensile force on the thermomechanical behavior of various polymers has been followed over the range 20 to 100 kg/cm2 and within wide temperature limits ( −150° to 250°). Ribbons 50 mm long, 2 to 4 mm wide and 0.05 to 0.5 mm thick served as specimens. Of the crystalline polymers the study included: isotactic polypropylene, polyethylene, polytetrafluoroethylene and polyethyleneterephthalate; of the amorphous: polyethyleneterephthalate and styrene-butadiene SKS-80 copolymer. The simplest thermomechanical curves were those of the amorphous linear isotropic polymers. The curves are characterized by a point of inflexion—abrupt increase in deformation on reaching the softening point. The thermomechanical curves of crystalline polymers are more complicated and are characterized by three differing regions of creep: below the glass, temperature, cold flow and the beginning of melting.
Molecular Structure and Properties of Polybutadiene Rubbers
Authors: Blümel H. 
Published: February 2011

Abstract
A discussion of the development, present day applications, and the advantages of polybutadienes are presented. The variations of an over-all concept in products obtained through different preparations and having various molecular structures as well as differing service and technological properties were made the starting point for the present investigations. Section 2 provides a review of the basic characteristics of the most important processes for preparing polybutadiene and the associated structural or compositional characteristics. Fourteen typical polybutadienes encompassing the entire range of polybutadienes are compared to cold rubber and natural rubber with respect to their most importance analytical and polymer values corresponding to their arrangement into preparation groups. The correlations between the technological properties of the raw rubbers, of the compounds, including the mixing behavior, and the vulcanizates on the one hand and the molecular structure composition of the rubbers upon which they are based, on the other, are discussed using detailed synopses in Sections 3 and 4. In doing this, it was important to see the principal features of the different polybutadienes compared to one another, effects of the structural characteristics and of additives on the properties of the raw rubbers, compounds, and vulcanizates, as well as the differences encountered as compared to polymers which are considered most important for use in blends (cold SBR and natural rubber). Finally, in Section 5, in summary form, the effects were treated of the individually appearing structural and compositional factors in the initial polymers on the service and technological properties of the raw rubbers, compounds, and vulcanizates.
The Viscurometer—An Instrument to Assess Processing Characteristics
Authors: Juve A. E. , Karper P. W. , Schroyer L. O. , Veith A. G. 
Published: February 2011

Abstract
This paper describes an apparatus that measures three important rubber processing characteristics—the compounded viscosity, the scorch time and the time to optimum cure. The apparatus is called a Viscurometer and consists of a heated die chamber and a drive mechanism to rotate a biconical rotor in an oscillatory manner through a fixed arc of ±6°. A strain gage torque pickup is mounted as an integral part of the drive shaft and the torque to impose the strain of ±6° (35% shear strain) is measured. The frequency of this oscillation is 2 per minute. A torque vs. time trace is recorded on a strip chart recorder. Data in graphical form are presented to show that the compounded viscosity of NR and SBR stocks correlates well with typical Mooney viscosity values. The scorch time, as measured with the Viscurometer, also correlates well with Mooney scorch values. The apparatus can be used to predict optimum cure for typical production SBR and NR stocks with a one standard deviation precision of ±2 minutes. The apparatus can also be used to predict the cured modulus at full cure (or any other percentage) under some conditions. This use of the Viscurometer is, however, more complex than its use to predict the previously mentioned processing parameters. The complexity of this use is illustrated for some typical NR and SBR stocks.