bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Theory of the Thermodynamic Behavior of Nonelectrolyte Solutions. II. Application to the System Rubber-Benzene
Authors: Maron Samuel H. , Nakajima Nobuyuki 
Published: February 2011

Abstract
The theories of polymer solutions proposed by Flory, Huggins, Miller, and Guggenheim employ the concept of a coiling polymer molecule which may become entangled with other such molecules in solution, and utilize statistical-mechanical considerations to obtain the thermodynamic relations attending the solution or mixing process. The theories of Flory and Huggins are essentially identical, as are those of Miller and Guggenheim. Further, all theories reduce to practically the same result when the molecular weight of the polymer is high. The present status of these theories may be summarized as follows. Except for dilute solutions, the free energies of mixing predicted by theory agree generally quite well with those measured experimentally; however, the heats and entropies of mixing do not. To correct the situation in the dilute region, Flory and Krigbaum developed a special theory which preserves the original model used by Flory, but attempts to take into account the lesser tangling of polymer chains as the solution is diluted. The latter theory appears to work quite well in very dilute solutions, but it suffers from two shortcomings. First, the theory does not apply to concentrations high enough to overlap the original theories, and hence there is a concentration gap for which no theory is available. Second, the Flory-Krigbaum theory employs parameters which are different in significance from those used at the higher concentrations, and, thus far, no relation has been established between them. The result is that polymer solution behavior at low concentrations is expressed in terms of one set of parameters, that at higher concentrations in another, and no means are available to connect these or to cover the concentration gap to which neither theory applies. Recently Maron7 developed a theory of the thermodynamic behavior of nonelectrolyte solutions which is nonstatistical in character, and which expresses the behavior of solutions in terms of parameters whose significance remains unaltered over the full concentration range of the solution. The purpose of the present paper is to show the application of this theory to the system rubber-benzene, for which Gee and Treloar have determined at 25° C the free energies, heats, and entropies of mixing over the entire range of concentration from pure benzene to pure rubber. Subsequent papers in the series will give applications of the theory to osmotic pressure and light scattering behavior of polymer solutions, as well as to the thermodynamic behavior of solutions of low molecular weight substances.
The Determination of Zinc Oxide in Rubber Vulcanizates by X-Ray Diffraction
Authors: Laning Stephen H. , Wagner Melvin P. , Sellers John W. 
Published: February 2011

Abstract
Zinc oxide is a necessary component in most accelerator-sulfur vulcanization systems. While it is not an accelerator, its presence leads to increased modulus, i.e., tighter cures. The manner in which it can effect this better cure is not completely clear. Some insight into the role of zinc oxide has been gained through the analysis of the vulcanizate for reaction products of zinc, such as zinc stearate, the zinc salts of the accelerators, and zinc sulfide. However, these products may not account for all of the zinc oxide which has reacted. An analytical method for the direct determination of unreacted zinc oxide in vulcanizates was therefore needed. The determination of zinc oxide in rubber vulcanizates has received scant attention. Wet-chemical techniques for analysis of the sample after ashing provide only the total amount of zinc from which the amount of unreacted zinc oxide cannot be determined. Endter has reported the use of the Debye-Scherrer x-ray technique for the identification of zinc oxide in rubber samples. While similar to the method developed in this laboratory, Endter employed photographic film for recording the diffraction pattern, and special sample preparation was required to accommodate the photographic technique. This method was satisfactory for qualitative identification of zinc oxide, but was difficult to use for quantitative analysis. Subsequent to this investigation Hagino et al. described the use of x-ray diffractometry for the determination of the mixing ratio of ingredients compounded in rubber. This method was also suggested for the quantitative analysis of zinc oxide, but no studies were reported. During a study in this laboratory to determine the role of zinc oxide in the vulcanization of rubber, a new analytical method, based on x-ray diffractometry, was developed. The method was rapid, nondestructive, and simple. The data were reliable and accurate.
Migration and Distribution of Radioactive Sulfur in Compounded Rubber
Authors: Blokh G. A. , Demidionova V. Ya , Miklukhin G. P. , Kukhtenko I. I. , Rekasheva A. F. , Nikulina R. V. , Przhebylskiĭ M. I. 
Published: February 2011

Abstract
In the production of vulcanized rubber articles it is necessary to take into account the possibility of migration of sulfur from one ply into another. It is well-known that alterations in the concentration of sulfur and accelerators in a stock, taking place as a result of diffusion processes, may lead to alteration in the quality of the rubber. In particular, if in formulating mixes for multiply rubber-fabric articles we take into account the migration processes of the accelerating and vulcanizing agents, it becomes possible to prevent the occurrence of various defects through nonuniform vulcanization. Once again, if the unvulcanized stock is stored in piles, migration means that alterations in the concentration of sulfur and accelerators cannot be ruled out. Another factor closely connected with the quality of the resulting articles is the uniformity of distribution of the sulfur when added to a compounded stock. Thus the study of migration processes takes on considerable practical importance. One promising method of investigation of diffusion processes in vulcanized rubber may be the use of tagged atoms. With it we can effectively and rapidly investigate migration processes at different stages of manufacture. The significance of this method for the investigation of the mechanism of the action of accelerator and vulcanization agents has already been pointed out in the literature. We used the tagged atom method in the investigation described below … a joint investigation by the rubber department of the Kiev Technological Institute of Light Industry, the Institute of Physical Chemistry of the Academy of Sciences of the Ukrainian SSR, and the “Krasnyi Rezinshchik” and “Ukrkabel” works.
The Vulcanization of Rubber under High Pressure
Authors: Okhrimenko I. S. 
Published: February 2011

Abstract
1. The influence of high pressures (up to 10,000 kg/cm2) on the cure of gum and compounded rubbers and also on the properties of the resulting products was studied. 2. It was demonstrated that high pressure accelerates vulcanization and effects the specific formation of stable carbon-carbon crosslinks. Thus, crosslinked polymers may be prepared without any vulcanizing agents, yet the resulting vulcanizates have excellent properties. New methods were designated for obtaining crosslinked block polymers having stable crosslinks. 3. It was determined that cure depends on the reactivity of the rubber, the type of unsaturation and, most important, the amount of spatially more accessible external double bonds. 4. It was shown that during the cure of rubber compounds under high pressure the participation of sulfur in the formation of the vulcanizate is substantially decreased. In a mixture of SKB rubber and sulfur the dominating reaction is the interaction of molecules of rubber. Functional fillers and softeners do not undergo substantial change. The use of initiators of radical polymerization contributes by leading to ultrarapid vulcanization of rubber. 5. An assumption is stated concerning the mechanism of vulcanizing rubber under high pressure as well as certain questions about the use of high pressure as a new method of producing molded rubber articles.
Reversion during TMTD Vulcanization
Authors: Dogadkin B. A. , Shershnev V. A. , Dobromislova A. V. 
Published: February 2011

Abstract
1) Reduction of crosslink density of vulcanizates (reversion of vulcanization) is observed during vulcanization of a mixture prepared in air of NR and SKI with TMTD without metal oxides and with magnesium and calcium oxides. In these cases the dimethyldithiocarbamic acid formed during vulcanization decomposes into carbon disulfide and dimethylamine. 2) During mixing and curing of these mixtures in an argon atmosphere reversion is absent although evolution of carbon disulfide and dimethylamine is observed. 3) During vulcanization of the mixtures containing zinc oxide no reversion occurs as a result of preparation of the mixtures either in air or in argon. Dimethyldithiocarbamic acid in this case is bound in the form of the stable zinc dimethyldithiocarbamate. 4) Reversion of rubber by TMTD is explained by oxidative destructive processes which are intensified by the products of decomposition of dimethyldithiocarbamic acid, i.e., by carbon disulfide and dimethylamine, and are suppressed by reaction of it to form zinc dimethyldithiocarbamate which serves as an inhibitor of the oxidative destruction of the vulcanizate.
Diisocyanate-Linked Polymers. II. Mechanical and Swelling Properties of Some Polyurethane Elastomers
Authors: Smith Thor L. , Magnusson Alan B. 
Published: February 2011

Abstract
In recent years, as a result of pioneering work in Germany and England, diisocyanate-linked polymers have assumed increasing industrial importance. Special interest is being shown in elastomers and foams, although studies of fibers and plastics are continuing. These several classes of diisocyanate-linked polymers, with their markedly different mechanical properties, are possible because substances having two or more groups containing active hydrogen can potentially be linked by diisocyanates to yield a polymer. Since a great number of such substances exist, data which show relationships between polymer structure and mechanical properties have practical importance as well as theoretical interest. The first paper of this series on diisocyanate-linked polymers discussed the dilute solution properties of linear polymers prepared from toluene-2,4-diisocyanate and polyoxypropylene glycol 2025 (PPG). This paper discusses the properties of one class of diisocyanate-linked elastomers prepared by a one-step cast technique, i.e., all reactants are mixed together initially and then allowed to cure. Although these polyurethane elastomers have relatively poor mechanical properties as compared with certain other types of polyurethane elastomers, they are useful in applications where high tensile strength, tear resistance, and ultimate elongation are not required. They also constitute a class of polyurethane polymers convenient for use in studying relationships between chemical structure and mechanical properties.
Rheological Testing of Elastomers at Low Temperatures. Part II
Authors: Boor L. , Hanok M. , Conant F. S. , Scoville W. E. 
Published: February 2011

Abstract
Results are given from a cooperative study to determine the extent to which certain superposition principles are applicable to analysis of different typos of deformation of elastomeric materials. Briefly, these principles are : (1) recovery rate from an equilibrium deformation after removal of a given load is equivalent to the creep rate from zero deformation upon application of that load and, (2) creep, recovery, or stress relaxation curves obtained at different temperatures can be pieced together into a continuous curve of time versus deformation or stress. Both principles are predicated on the use of an essentially equilibrium deformation or stress as a base from which the percentage change with time is calculated. The first of the above principles was demonstrated for both torsional and shear deformations, but not for tensile deformations, possibly because of some inaccuracy in the test method. The second principle was demonstrated for shear creep, shear recovery, torsional creep, torsional recovery, and tensile stress relaxation. Applications of this method of analysis are given to show how the rheological behavior of an elastomer at a given temperature may be predicted for very short or for very long periods of creep, recovery, or stress relaxation from measurements made at a series of temperatures.
Determination of Copolymer Composition by Combustion Analysis for Carbon and Hydrogen
Authors: Wood Lawrence A. , Madorsky Irving , Paulson Rolf A. 
Published: February 2011

Abstract
The procedure described attains its accuracy and precision by the refinement and improvement of conventional simple operations over a periods of years. The trend in analysis recently is, of course, toward the use of rapid physical methods. In a great many instances these involve relative measurements requiring the initial establishment of reference materials with compositions determined by methods such as the one here described, which bases the numbers derived solely on readings of an analytical balance. In fact, as already mentioned, one of the principal applications of the present method has been in the establishment of the relation between refractive index and styrene content for SBR polymers so that refractive index measurements can be used in routine determinations of bound styrene content.
The Attack of Ozone on Stretched Rubber Vulcanizates. II. Conditions for Cut Growth
Authors: Braden M. , Gent A. N. 
Published: February 2011

Abstract
In Part I an experimental study was reported of the factors determining the rate of propagation of a cut through a stretched rubber sheet under the action of an atmosphere containing ozone. It was remarked that no growth took place from a small razor cut made in one edge of the test pieces unless a critical value of the applied tensile stress was exceeded. The value was quite small, of the order of 100 g/cm2 for a soft natural rubber vulcanizate. In the present part an examination is reported of the conditions necessary for a crack to form or, being present, to grow.
The Nature of an Adhesion Bond between Two High-Molecular Weight Compounds
Authors: Morozova L. P. , Krotova N. A. 
Published: February 2011

Abstract
1. The nature of the adhesion bonds in different cases can be determined by investigations of the mechanical characteristics of adhesion, of electrical effects observed on destruction of the bond, and microscopical investigation of the separation boundaries in various systems consisting of polymer pairs, and polymer-metal and polymer-glass systems held together by forces of adhesion. 2. The adhesion bonds between polymer and metal and polymer and glass are electrical in character, as shown by the form of the adhesiogram, the occurrence of electron emission on separation, and the existence of electric charges on the separated surfaces. 3. After separation, the polymer film continues to emit electrons and carries a negative residual charge. The substrate (glass, metal) does not emit electrons and has a positive charge. 4. The breakdown of the adhesion bond between two polar polymers of different structure, or a polar and nonpolar polymer, is accompanied by the same characteristic effects as the separation of a polymer from glass or metal. A sharp boundary is observed in microscopic specimens. 5. Determinations of the velocities of electrons emitted during separation show that breakdown of a firm adhesion bond is accompanied by emission of electrons with higher velocities than those emitted in the breakdown of a weak bond. These results arc in good agreement with the electrical theory of adhesion. 6. The reaction of the substrate (glass) has a strong influence on the adhesion of a polymer (chlorinated polyvinyl chloride) to it. The maximum adhesion is found in the neutral region. The detached polymer film shows a reversal of residual charge in the strongly acid and strongly alkaline regions, accompanied by a sharp decrease of the work of adhesion; this can only be attributed to a decrease of the surface electrification density of the layers of the electric double layer in the charge reversal region. 7. Mechanical treatment of the metal surface increases the adhesion of polymers to it and intensifies electron emission from the regions of the polymer film which were attached to the treated regions of the metal surface. 8. The formation of an adhesion bond between two nonpolar polymers of similar structure is caused by diffusion processes in the contact zone. In such cases no electrical effects are observed during separation, the boundary in microscopic specimens is diffuse, and the work of separation depends relatively little on the rate of separation. 9. The systems studied can be subdivided into two groups: the adhesion bond in systems of the first group is the result of formation of an electric double layer at the boundary; in systems of the second group the adhesion bond is produced by diffusion processes at the boundary.
Role of Pressure and Amount of Blowing Agent in Molding Microporous Footwear Parts
Authors: Al'bam M. A. , Pisarenko A. P. 
Published: February 2011

Abstract
In the All-Union Film-forming Materials and Artificial Leather Research Institute (VNIIPIK) investigations have been in progress for several years with a view to developing a rational method of production of microporous footwear parts, and to eliminating completely expansion of the parts on removal from the press. It had already been demonstrated that to produce microporous molded parts strictly to the set shape they must be vulcanized with an external pressure not exceeding a certain critical value for each stock formula depending upon the amount of blowing agent, the flowability of the stock and the temperature. However the cause of this marked dependence of the process of molding of microporous parts upon the external pressure was not explained. It was merely suggested that a big part was played by the escape of gas from the cells of the molded rubber. In order to work out a theoretical basis for the production of molded parts and for the control of the process of pore formation, it was necessary to study the essential nature of the process. For this purpose we studied the kinetics of the process of pore formation and of the escape of gas from a stock in the process of vulcanization. The method worked out for investigation of the process of pore formation made it possible to study this process under conditions fully corresponding to the actual production conditions of press vulcanization, and to follow simultaneously in one experiment the change in volume of the vulcanization stock and the escape of gas from it. On the basis of these data we plotted the kinetic curves for the processes.
Mechanochemical Phenomena in Polymers. II. The Effects of Initiators and Inhibitors of Radical Processes
Authors: Reztsova E. V. , Lipkina B. G. , Slonimskiĭ G. L. 
Published: February 2011

Abstract
1. The substantial effect of inhibitors and initiators of chain radical processes on the change in the properties of rubbers in milling, as well as on the resistance of vulcanizates to fatigue, has been shown. This indicates a mechanochemical mechanism of the processes occurring in processing polymers and of the fatigue of highly elastic materials (e.g., rubber vulcanizates). The act of mechanical scission of chemical bonds, with the formation of free radicals which initiate the secondary chain processes, rests on these processes. 2. The possibility has been shown of regulating the properties of polymers in the course of their industrial processing, and also of increasing the dynamic fatigue resistance of vulcanizates by incorporating small quantities of additives active in regard to free radicals.
The Effect of Electric Charges Formed during Repeated Deformations on the Fatigue Resistance of Vulcanizates
Authors: Dogadkin B. A. , Gul V. E. , Morozova N. A. 
Published: February 2011

Abstract
Electroelastic and triboelastic effects result in the formation of electric charges on articles made from polymers undergoing deformation. It was of interest to determine the effect of the charges formed during deformation on the fatigue resistance of vulcanizates. No convincing experiments clearly demonstrating the role of electric charges arising during friction or deformation had been carried out previously. Vulcanizates containing different amounts of acetylene black were tested in a machine in which cylindrical specimens with thickened ends were subjected to repeated bending at 1300 cycles/minute. The stocks had the following composition (in parts by weight) : SKS-30A 100, sulfur 2, technical stearin 2, Rubrax 5, black oil 4, MBTS 0.6, diphenylguanidine 0.8, zinc oxide 5, oleic acid 1. Increasing amounts of acetylene black were added to this composition: 6, 12, 18, 20, 22, 30, 40 and 75 wt. parts per 100 wt. parts of rubber.
Analysis of Cis and Trans 1,4 Contents of Polyisoprenes by Near Infrared Spectroscopy
Authors: Corish P. J. 
Published: February 2011

Abstract
A new method for the determination of cis and trans-1,4 units in synthetic polyisoprenes and gutta-rubber mixtures has been developed. The method uses the near infrared region of the spectrum and gives better, more reproducible results than the one using the normal infrared region.
Statistical Treatments of Rubber Structure
Authors: Scanlan J. , Watson W. F. 
Published: February 2011

Abstract
Chemical reactions are random in nature and can therefore be subjected to mathematical analyses based on probability theory. This is a particularly necessary approach to polymer structure in which the effect of chance inherent in the reactions is preserved in physical form and therefore much attention has been given to deductions from such treatments. It is the purpose of this paper to review the results of those investigations which have particular application to rubbery high polymers. Some emphasis will be given to the authors' view that experimental testing of the derived expressions is still far from being satisfactory and that the subject in spite of the effort expended is still only at its beginning. Consideration of details of polymer structure is not merely an academic exercise. The properties of raw rubbers are highly dependent on polymer chain length and for many important ones such as viscosity, either in solution or in the melt, the dependence is not simply linear. Unless linear dependence on the number of molecules and their size does apply, an average value of molecular weight is insufficient to characterize a rubber sample in respect of the property considered and further knowledge of the distribution of molecular weights among the rubber molecules is required. The properties of rubbers are also markedly influenced by the occurrence of branching in the polymer chains; the insolubility and elasticity conferred by vulcanization are the results of the formation of complex branched structures which have been the subjects for statistical treatments.
The Relations between Polymer Structure and Properties in Urethans
Authors: Saunders J. H. 
Published: February 2011

Abstract
Sufficient data are available from studies of urethan foams and elastomers to draw semiquantitative conclusions regarding the effect of any gross structural change on most polymer properties. These relationships apply to other areas of application as well, e.g., coatings, adhesives and sealants. Future research may be expected to provide more reliable control of the many reactions involved in preparing urethans, thus better control over structure. Similarly a more quantitative and extensive knowledge of polymer properties may be expected. The result of these combined efforts will be a more precise knowledge of structure-property relationships and an improved ability to produce polymers having the properties desired for a wide range of applications.