bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vulcanization of Elastomers. 45. Experiments to Determine the Huggins Interaction Parameter
Authors: Hummel K. 
Published: February 2011

Abstract
A new method is described for determining the Huggins interaction parameter, µ. It is characterized by the measurement of the equilibrium swelling of two completely reacted vulcanizates for which the initial composition is known. The method gives correct results only under definite assumptions which are explained for the case of natural rubber crosslinked by dicumyl peroxide. Its applicability is demonstrated for the system natural rubber/benzene at 25° C; the results, however, scatter considerably.
Quantitative Relationship between Mineral Oil Composition and Elastomer-Extender Interaction Parameter
Authors: Bruzzone M. , Modini G. 
Published: February 2011

Abstract
Among the synthetic rubbers, the styrene-butadiene elastomers (SBR) extended with oil have grown more and more important in these last years. These elastomers are obtained by masterbatching an SBR latex of high Mooney viscosity with a mineral oil before coagulation, the oil content normally ranging between 37.5% and 50%. The mineral oil can be classified as predominantly paraffinic, naphthenic, or aromatic according to the ratio of carbon atoms involved in the paraffinic, naphthenic, or aromatic structures. The oil composition greatly affects both the processing and the final-product properties of the extended elastomer. It is well known, for instance, that SBR extended with paraffinic oil is more critical in processing than when extended with naphthenic or aromatic oils, and, on the other hand, that SBR extended with paraffinic oil shows better resistance to the discoloration caused by exposure to light. Leaving the long list of the effects on elastomeric properties of oil composition to the many papers existing on this subject, we prefer to deal here with a very important subject not very much studied on any quantitative basis until now. The oil composition affects many characteristics of the polymer because it brings controllable variation to the physical-chemical interaction between the polymer and the extender, measurable by the Flory-Huggins interaction parameter and strictly related to the more commonly known compatibility meaning. This work deals with the quantitative relationship between the composition of various mineral oils (determined by a well-known method) and their interaction parameters with SBR which greatly affect the main properties of the extended elastomer and which we determine by a swelling measurement of the crosslinked elastomer.
The Elasticity of Rubber-Bitumen Binders for Use in Roads
Authors: de Merlier Jacqueline , Leveque J. , Curchod J. 
Published: February 2011

Abstract
The authors have first described test methods used, on the one part, to determine, in a simple way, the elastic recovery of binders after deformation, and on the other, to characterize accurately the state of degradation of the rubber within the bitumen by assessing the molecular weight of the dispersed polymer. Analysis and interpretation of results have stressed: (a) the effect of the molecular weight of crude natural rubber on the elastic recovery of bitumen-rubber blends; (b) the effect of the way in which bitumen-crude natural rubber blends are prepared on their elastic properties and (c) the effect of the nature of synthetic elastomers on the elasticity of bitumen blends.
Effect of Peperidine on Rubber Solutions
Authors: Soininen A. , Bäsk W. , Pehu-Lehtonen A-L. 
Published: February 2011

Abstract
In the experiments which have been described, the viscosity measurement served as an indicator to establish the amount of piperidine required for a substantial viscosity reduction. The bend in the viscosity curves for the 5% crepe solutions occurred for a piperidine addition of about 3×10−5 moles. The quantity appears to be in stoichiometric relation to the rubber used. Therefore we come to the view of Meyer, that rubber exhibits associating, oxygen-containing groups. Accordingly, the strong effect of piperidine in lowering the viscosity is due to the action of this amine in splitting all the association bonds of the oxygen-containing groups in the rubber molecules. Not only the weak alcohol and keto bonds are concerned but also the strong carboxyl bonds. Infrared spectroscopy also has shown that Hevea rubber contains a rather large portion of such groups. These probably are first formed in the processing of the latex. It is quite possible that the rubber molecules associate with the help of carboxyl groups, as carboxylic acids generally do, and form the relatively stable dimer compound shown below with two hydrogen bonds:
Tetracyclosqualene and Its Bearing on the Structure of Cyclized Rubber
Authors: Golub Morton A. , Heller Jorge 
Published: February 2011

Abstract
Recently we reported that cyclized rubber consists of six-membered rings fused into predominantly bicyclic structures which are connected by methylene groups and/or uncyclized isoprene units. Each of the fused ring structures is presumed to contain a single tetra-, tri- or di-substituted double bond, the relative amounts of which are in the order, tetra- &gt; tri- &gt; di-substituted. The predominantly bicyclic structure was not rigorously established, but it was considered reasonable on the basis of a comparison of the nmr spectra of cyclized cis-polyisoprene and cyclized cis-poly (2-methyl-d3-1,3-butadiene-1,1-d2). However, although a predominantly monocyclic structure was clearly excluded, it was not possible to rule out a structure in which the average number of rings per fused segment (“cyclicity”) exceeds two and may even be as high as three. In an effort to determine this cyclicity more accurately, we now compare the nmr and ir spectra of cyclized cis- and trans-polyisoprenes with the corresponding spectra of tetracyclosqualene (TCS). The latter is known to have a structure consisting of two bicyclic segments connected by two methylene groups.
Estimation, from Swelling, of the Structural Contribution of Chemical Reactions to the Vulcanization of Natural Rubber. Part I. General Method
Authors: Ellis Bryan , Welding G. N. 
Published: February 2011

Abstract
A procedure is described for estimating indirectly the contribution of vulcanization reactions to the build-up of network structure. This method is useful with technically important vulcanizing systems for which no direct method of estimation has been found. Errors of the theory of high elasticity are avoided by using published results, such as those of Moore and Watson of direct chemical estimates obtained with a special vulcanizing system that is chemically well understood. Reliance on the theories of end correction and swelling is also avoided by using published experimental relations. The method is applicable to any linear primary polymer of arbitrary molecular weight and any suitable swelling liquid, for which the required reference data have been obtained.
Estimation, from Swelling, of the Structural Contribution of Chemical Reactions to the Vulcanization of Natural Rubber. Part III. Restricted Method
Authors: Russell R. M. , Smith D. A. , Welding G. N. 
Published: February 2011

Abstract
A method is described whereby the structural contribution of vulcanizing reactions may be estimated graphically from measurements of the equilibrium volume fraction of rubber in a vulcanizate swollen in n-decanc at 25.0°. Use is made of the data of Moore and Watson represented in the form of a relation between (ρMc−1)vulc and υτ. The method is applicable with technically important vulcanizing systems for which no direct method of estimation is available, and is simpler than the previous method (Part I). The method is limited to natural rubber of fixed primary molecular weight, but the limitation avoids a large correction for free ends of chains. Suitable experimental techniques are described.
Viscous Flow and Flow Temperature of Polymers
Authors: Sogolova T. I. , Slonimskii G. L. , Kargin V. A. 
Published: February 2011

Abstract
In recent years, E. V. Kuvshinskii and colleagues have published a series of articles devoted to thermomechanical studies of polymers. Some of these, together with some interesting data, led to strange conclusions concerning the absence of flow in polyisobutylene, polystyrene, and polymethylmethacrylate in thermomechanical experiments and also to the uselessness of distinguishing between the viscous flow state development and determination of flow temperatures of polymers. Obviously feeling a weakness in their argument, the authors of these articles showed, at the same time, that their results “do not refute the possibility of using the data from thermomechanical studies for technological purposes, including the establishment of proper temperatures for processing polymeric materials” (Ref. 1, p. 1704). We have established the fact that the position taken by E. V. Kuvshinskii and associates, in which they deny the existence of the viscous flow state of polymers and characterize flow temperatures, is in sharp contradiction to the current thinking concerning mechanical properties and structure of polymers. Their position adds nothing to our knowledge of the properties of polymers. Furthermore, their position is dangerous, because it docs not contribute to the clarification of the various phenomena taking place during the flow of polymers. This leads to confusion.
Vulcanization. Part I. Fate of Curing System during the Sulfur Vulcanization of Natural Rubber Accelerated by Benzothiazole Derivatives
Authors: Campbell R. H. , Wise R. W. 
Published: February 2011

Abstract
Several investigators have proposed mechanisms for the delayed action sulfur vulcanization of rubbers which postulate that a number of intermediate compounds containing fragments of the accelerator are formed during the vulcanization cycle. Although a number of workers have measured the change in initial accelerator and sulfur concentration in the rubber during vulcanization, none have identified and determined the intermediate compounds which appear to be formed during vulcanization. The purpose of this paper is to first confirm the existence of these intermediates and subsequently to identify and quantitatively follow their concentrations throughout the vulcanization cycle. In our initial studies we have limited our investigations to natural rubber cured with sulfur and accelerated with (i) MBT (2-mercaptobenzothiazole), (ii) (MBTS)[2,2′-dithiobisbenzothiazole)], and (iii) 2-(4-morpholinothio)benzothiazole. In order to reduce the complexity of the system, other normally used additional curing agents, notably ZnO and stearic acid, have been deleted.
Vulcanization. Part IV. The Effects of Compounding Variables on the Nature of Rubber Networks
Authors: Coran A. Y. 
Published: February 2011

Abstract
It is generally accepted for sulfur vulcanizates of natural rubber that the crosslinks consist of monosulfidic and polysulfidic links between polymer chains. There is indication in the literature that the average number of sulfur atoms per crosslink decreases with an increasing ratio of accelerator concentration to sulfur concentration. Further work was needed and in Paper III of this series a rapid method for determining the relative proportions of monosulfidic and polysulfidic crosslinks was described. The method was based on solvent swelling measurements of thin film vulcanizates before and after a lithium aluminum hydride reduction. By using this method along with a newly developed method for measuring stress-relaxation in a Monsanto Oscillating Disk Rheometer, it is possible to determine the relative proportions of three types of crosslinks: those which are nonreducible, those which are reducible but not rapidly stress-relaxable and those which are reducible and rapidly stress-relaxable. It is assumed that the stress-relaxation is due to cleavage of some of the polysulfidic crosslinks, but not others (those of the type R—S—S—R). It was our purpose here to define network characteristics as a function of compounding variations. The networks were characterized in respect to the distributions of the types of crosslinks as well as the number of crosslinks. It is felt that the nature of the networks as measured on the microscale would be significantly reflected in gross properties; this should be borne out in future studies.
Vulcanization of Elastomers. 46. The Kinetics of Crosslinking
Authors: Scheele W. , Hillmer K.-H. 
Published: February 2011

Abstract
The present article represents a first contribution to the investigation of the crosslinking kinetics of 1,5-polyenes, with sulfur as the vulcanizing agent. It is principally concerned with working out the pertinent methodology, and hence is a report on our experience with the “Agfa Vulcameter” (also called the Bayer Vulcameter). Using as an example the zinc benzothiazolyl mercaptide (ZnMBT)/zine stearate accelerated vulcanization of natural rubber with sulfur, which in any case runs with practically no reversion at moderate temperatures, and thus permits an experimental determination of the crosslinking end-values, we were able to show that crosslinking can be described quantitatively and qualitatively with the help of an Agfa Vulcameter. It was proved that the same reaction order and the same rates are obtained, as when the static modulus is used as the criterion for crosslinking. The scientific and practical importance of the results are pointed out.
Identification of Elastomers by Gas Chromatography Applied to Pyroluzates
Authors: Fiorenza Aldo , Bonomi Giuseppe 
Published: February 2011

Abstract
The general principles on which gas chromatography is based are reviewed, followed by a discussion of partition chromatography in particular. Certain typos of detectors are described as well as columns and column heating systems. There follows a review of the analysis of polymers by means of gas-chromatography. The methods employed for the examination of elastomers are also described. Finally, the chromatograms of various elastomers and their mixtures are presented which were obtained by using different types of columns.
On the Plasticization of PVC by Polyisoprene SKN-40
Authors: Byl'ev V. A. , Voskresenskii V. A. 
Published: February 2011

Abstract
The authors investigated the process of plasticizing PVC by SKN-40 synthetic rubber in the mixing of the components in the solid phase on hot rolls. It is found that with the optimum conditions the components mix in any desired ratio to form uniform strong and transparent films, having sufficiently high resistance to gasoline and water. It is shown that the addition of 1% sulfur to the system considerably enhances the mechanical properties of the compositions and their water resistance.
Reinforcement of Butyl with Carbon Black. II. Thermally vs. Chemically Oxidized Blacks
Authors: Gessler A. M. 
Published: February 2011

Abstract
The effect of oxidized blacks on the stress-strain properties and bound-rubber content of butyl and SBR was discussed in the preceding paper. Oxidized blacks, when compared with similar untreated blacks, were shown to have a greatly increased reinforcing capacity in butyl. Oxygen functionality on carbon black, it was therefore concluded, is essential in butyl to produce the chemical reactivity which is required between polymer and black if high-order reinforcement is to be obtained. Oxygen functionality on carbon black, it was also demonstrated, is not only not required for enhanced reinforcement in SBR, but it is in fact a deterrent, because it exerts severe restraining effects on the cure of the resulting vulcanizates as well. These interesting results were proposed to provide qualitative but convincing evidence that carbon-polymer bonding, which we believe is requisite to reinforcement, is achieved by different mechanisms in butyl and SBR. In butyl, the unique sensitivity of the stress-strain curve to reinforcing effects was used to speculate on the disposition of carbon blacks in “filled” and reinforced vulcanizates, respectively. With oxidized blacks, reinforcement effects were pictured as stiffening effects which, starting with the gum vulcanizates, caused the stress-strain curve to be shifted without intrinsic changes in its shape. The resulting “reinforced gum,” it was suggested, derived its physical characteristics from the fact that carbon black was included in the vulcanized rubber network. With untreated blacks, in “filled” systems, carbon black was pictured as being enmeshed or entangled in an independently formed vulcanized rubber network. The stiffening effects in this case were attributed to viscous contributions arising from steric restrictions which the occluded carbon particles were thought to impose on both initial movements and the subsequent orientation of network chains when the sample was extended.
Ultimate Tensile Properties of Elastomers. II. Comparison of Failure Envelopes for Unfilled Vulcanizates
Authors: Smith Thor L. 
Published: February 2011

Abstract
The tensile stress-at-break σb (based on the initial cross-sectional area) and the corresponding ultimate extension ratio λb of unfilled vulcanizates of silicone, hydrofluorocarbon (Viton B), butyl (both sulfur-cured and resin-cured), and natural rubber were determined at many strain rates and temperatures; the latter ranged from slightly above the glass transition temperature Tg, up to a temperature somewhat below that at which chemical degradation affected the results. For each vulcanizate except natural rubber, data obtained over an extended temperature range superposed to give a time- and temperature-independent failure envelope on a plot of log (σb273/T) vs log (λb−1), where T is the test temperature in °K; for natural rubber, data obtained between 90° and 120° C superposed, but those at lower temperatures did not because of strain-induced crystallization. For each vulcanizate, data at elevated temperatures gave, or tended toward, a line of unit slope on a plot of log (λbσb273/T) vs log (λb−1), where λbσb is the breaking stress based on the cross-sectional area at the moment of rupture. The position of each line corresponded to the equilibrium modulus Ee derived from stress-strain curves. Failure envelopes previously obtained for two styrene—butadiene vulcanizates, which had different crosslink densities, superposed to give a master failure envelope on a plot of log (λbσb273/T) vs logEe(λb−1). On this type of plot, failure envelopes for all the vulcanizates except silicone and natural rubber were found to be essentially identical. At a given value of λbσb, silicone had a smaller λbλb and natural rubber a somewhat larger λbλb than the vulcanizates of the three other rubbery polymers.
Molecular Theory for the Tensile Strength of Gum Elastomers
Authors: Bueche F. , Halpin J. C. 
Published: February 2011

Abstract
The tensile strength and ultimate elongation properties of any given amorphous elastomer can be described by a characteristic failure curve. It is shown in this paper that the failure curve can be predicted from a knowledge of the creep curve of the elastomer together with the data from a Mooney-Rivlin plot. The theory relating the ultimate properties to the viscoelastic properties of the elastomer is based upon the idea of a propagating crack, the rate of propagation being limited by viscoelastic mechanisms. Data for the failure curves and creep response for EPR and SBR elastomers are presented and shown to support the theory. Literature data for butyl rubber are also shown to confirm the theory.
Dynamic Testing of Automotive Rubber Parts by the Resonant Beam Tester. Effect of Polymer, Deflection, Age, and Temperature on Dynamic Rate
Authors: Lowman M. , Keller H. E. 
Published: February 2011

Abstract
When the recipe is basically the same, different polymers differ in dynamic rate and damping. Ethylene—propylene terpolymer, SBR, neoprene, and butyl gave higher dynamic rate and higher damping than natural rubber, polyisoprene, and the blend of polyisoprene and cis 1,4-polybutadiene. The lowest dynamic rate and lowest damping is obtained with polyisoprene. At room temperature, polymers having the highest damping also have the largest ratio of dynamic to static rate. One cannot predict the effect of temperature on dynamic rate by measuring static rate at these temperatures. Increase in temperature lowers dynamic rate, decrease in temperature increases it. This effect was least with a blend of polyisoprene and cis 1,4-polybutadiene, closely followed by polyisoprene, and natural rubber. The largest change was with butyl. Dynamic rate increases with time after cure. After 26 hr, dynamic rate is a function of the logarithm of time. This effect is least with polyisoprene. Natural rubber, SBR, EPT, neoprene and a blend of polyisoprene with cis 1,4-polybutadiene all follow Equation (1). Butyl has, by far, the greatest change in dynamic rate with time. Reducing the deflection from 0.012 in. to 0.004 in. linearly increased the dynamic rate. Times of vibration between 2 minutes and 60 minutes at room temperature had no effect on dynamic rate.
Friction on Wet Surfaces of Tire-Tread-Type Vulcanizates
Authors: Sabey Barbara E. , Lupton G. N. 
Published: February 2011

Abstract
A laboratory investigation has been made into the variation with temperature of the hardness and resilience of a wide variety of rubber compounds of the tire tread type. The effect of hardness and resilience on the fractional properties of the compounds under wet conditions has also been studied. In the first series of tests the resilience and hardness of 25 compounds were measured over a temperature range 0° to 80° C. All were vulcanized tire tread type compounds, and the basic materials used comprised 14 natural rubbers, 7 styrene/butadiene (SBR) rubbers, 2 butyl, 1 polybutadiene, and 1 ethylene/propylene. The tests showed a marked increase in resilience with increasing temperature for all compounds except the polybutadiene; the hardness of all compounds changed very little with temperature, only a slight decrease being observed over the whole temperature rise. Nine compounds of representative resilience and hardness were selected for a second series of tests in which friction was measured over a temperature range 1° to 40° C on seven surfaces representing roads of different textures. For eight of the compounds, friction values decreased with increase in temperature; for the other compound the friction increased to a maximum value at 30° C. These changes in friction cannot be explained by changes in hardness of the compounds, but they are in accordance with resilience changes, taking into account the different test conditions obtaining in the friction and resilience tests. The friction tests also showed that with the portable skid-resistance tester used to measure friction the sharpness of the projections in the road surface is more important than their size in determining the friction values under wet conditions, even when rubber compounds of low resilience are used. The implications of the findings and their application to the study of friction between tire and road are discussed. In particular, they have a bearing on the correct interpretation of resilience measurements of tire tread materials in relation to friction values under wet conditions.
Polymer—Solvent Interaction Parameter and Creep of Ethylene—Propylene Rubber
Authors: Dudek T. J. , Bueche F. 
Published: February 2011

Abstract
The polymer—solvent interaction parameter for an ethylene—propylene ter-polymer containing 53 mole-% ethylene was determined as a function of degree of crosslinking in n-heptane and benzene. A well characterized EPR gum vulcanizate was used to obtain the polymer-solvent interaction parameter in fourteen solvents, and the cohesive energy density of the terpolymer was evaluated. The composite tensile creep curves for gum and filled EPR vulcanizates were obtained and compared with SBR creep curves.