bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Expansion Phenomena in Filled and Unfilled Natural Rubber Vulcanizates
Authors: Thiele J. L. , Cohen R. E. 
Published: February 2011

Abstract
As with polybutadiene and SBR compounds, filled and unfilled vulcanizates of natural rubber exhibit long transients in their linear thermal expansion response following sudden changes in temperature. This is particularly noticeable when the materials are prestretched well beyond the point of thermoelastic inversion. Incorporation of 50 phr of carbon black significantly reduces the magnitude of the linear thermal expansion coefficient for natural rubber compounds; this reduction is greater than expected on the basis of comparisons with previous data on filled SBR vulcanizates. Changes in the surface chemistry of the filler have little effect on the thermal expansion behavior. For the unfilled vulcanizate, an equation based on rubber elasticity theory was successful in predicting the strain dependence of the linear thermal expansion coefficient up to moderate levels of strain. At higher strains the large deviations from theory were observed.
Scanning Electron Microscopy Studies of Nitrile Rubber Fractured Surfaces
Authors: Bhowmick A. K. , Basu S. , De S. K. 
Published: February 2011

Abstract
The fracture surfaces of a NBR vulcanizate after different test conditions have been studied by scanning electron microscopy. It has been shown that failure surfaces manifest typical characteristics dependent on the nature of the test. Tensile fracture surface shows occurrence of two different tear rates in the case of a filled NBR vulcanizate, while tear fracture is characterized by a few long flow lines. De Mattia flexing leads to layering of polymer fibers. Heat buildup and abrasion tests generate a ribbed structure on the surface.
Improved Service Life of Automotive Suspension Bushings through the Use of Semi-Efficient Vulcanization Systems
Authors: Paris W. W. , Doney C. 
Published: February 2011

Abstract
The relative merits of antiozonants, efficient vulcanization systems, and semi-efficient vulcanization systems for natural rubber in dynamic applications have been previously evaluated in a number of laboratory studies. This report covers an evaluation of the effects of these three factors on the laboratory fatigue testing of automotive suspension bushings. The use of semi-efficient vulcanization systems along with a good soluble antioxidant will provide the optimum resistance to the combined effects of oxidation and mechanical fatigue experienced in this application. Efficient vulcanization systems produce products with very poor service life. The use of substituted p-phenylenediamine (ppd) antiozonants can be an advantage or disadvantage in compression fit bushings, depending upon the type of service. Excessive amounts of ppd at the rubber-to-metal interface can cause slippage and early failure; therefore, the use of ppd's must be approached with caution in this application.
Rubber Mixing
Authors: Funt J. M. 
Published: February 2011

Abstract
Model studies on particle dispersion have led to insights which have increased understanding of the mixing process. Despite the complex flows which arise in practical mixing equipment, model calculations have highlighted the essential flow patterns which occur and have guided understanding of the application and limits of use of practical techniques such as power integrators. Using these tools, process engineers have realized substantial savings in energy usage and mixing time, while maintaining or improving mix quality.
Reactions of Resin Formers in Dry Bonding Rubber Systems
Authors: Morita E. 
Published: February 2011

Abstract
An unusual two step viscosity change was observed during the Mooney scorch test of some dry bonding stocks of a NR/SBR blend. This behavior was found to involve the resin formation and resin crosslinking of rubber. The effects of the resin formers, hexamethylenetetramine as the methylene donor and resorcinol, m-aminophenol or m-phenylenediamine as the acceptor, were analyzed by the application of a prevulcanization inhibitor. The merits of m-phenylenediamine as an adhesion promoter are described.
A Non-Linear Viscoelastic Characterization of a Natural Rubber Gum Vulcanizate
Authors: Sullivan J. L. , Morman K. N. , Pett R. A. 
Published: February 2011

Abstract
The utility of the generalized strain measure viscoelastic equation (the CBT theory) has been demonstrated in part by excellent agreement of experiment with pure shear predictions calculated from simple tension results. Similar successes employing the generalized strain measure have been reported elsewhere. FLV predictions also demonstrated good correlation by matching predictions based on the CBT theory. However, in order to avoid excessive sensitivity to experimental error, regression parameters appearing in the FLV theory, especially for the “third order” form, were evaluated from data first smoothed using the CBT tensile elastic equation. In the future, we expect the “third order ” form to be useful at large deformations where more regression constants are needed to adequately characterize a broad deformational domain. Predictions of the storage modulus in simple tension based on either the FLV or the CBT theory agree with experiment to within approximately 10% error. Although this error is considered good from an engineering point of view, efforts are underway to identify its origin and to reduce its magnitude. Loss modulus predictions of either theory are only in semi-quantitative agreement with experiment. The frequency response of experimental E2 values is matched reasonably well by theory, but the deformational dependence of the data is lost due to relatively large scatter.
Contribution to the Mathematical Description of Stress-Strain Behavior of Elastomers
Authors: Tobisch K. 
Published: February 2011

Abstract
Based on the hypothesis of Valanis and Landel that the strain energy density function W(λx,λy,λz)could be represented as the sum of three identical functions ω(λi) of the principal extension ratios λi(i=x,y,z), an expression for ω(λi) is suggested which is distinguished by its relative simplicity. The stress-strain relations developed from this expression are tested successfully by applying them to experimental results of other authors. The types of strain which were examined were simple extension, biaxial extension and pure shear; the elongations were to about 700%.
Computation of Stresses, Strains, and Deformations of Tires
Authors: Ridha R. A. 
Published: February 2011

Abstract
The pneumatic tire is often taken for granted as a simple and reliable component of the vehicle. A closer look, however, shows that the tire in service is subjected to severe stresses and deformations whose quantities must be determined in order to accurately predict tire performance. Modern tire structures have evolved through a series of modifications of the original pneumatic rubber tire. These modifications were based on field experiences and on mostly experimental studies of tire behavior. The use of analytical techniques to calculate tire stresses and deformations remained limited in scope for a long time because the complexity of the tire structure placed it beyond the domain of available methods of analysis. The recent emphasis on analytical techniques is due, at least partly, to their potential for becoming less time consuming and less expensive than experimental methods, the need for predicting a tire's behavior before its manufacture, and the notable advances in computational and structural analysis methods. In this paper, these methods are described and applied to the calculation of tire stresses and deformations. Structural analysis is the analytical determination of structural responses to a prescribed set of applied loads. The responses may be displacements or distortions if force loads are known, or forces if displacement or distortions are known. Given the geometry of a structure (shape, dimensions), the relevant properties of its component materials, the magnitude and distribution of applied loads, and any constraints from boundary conditions, then structural analysis is used to calculate displacements, strains, or stresses at any chosen location in or on the structure. These calculated values may be compared to those required for functionality of the structure. Although structural analysis is not directly applicable to determining the most efficient configuration of the structural components, the analysis of successive well chosen modifications can often optimize compositions or geometries. The application of structural analysis to a tire requires (a) knowledge of the relevant physical properties of the component materials, and their configuration in the tire, (b) complete characterization of the applied loads, and (c) an analytical technique (i.e. theory) for calculating the required responses. These requirements are explained in the following sections.
Factors Affecting Cord-to-Rubber Adhesion by a Tire Cord Adhesion Test
Authors: Fielding-Russell G. S. , Livingston D. I. , Nicholson D. W. 
Published: February 2011

Abstract
The physical factors affecting the force required to pull a cord from the cord-rubber specimen used in a new tire cord adhesion test (TCAT) were investigated using a variety of rubber compounds, specimen cross-sectional areas, and tire cords. Below a limiting cross-sectional dimension, the cord pull-out force was proportional to the square root of cord perimeter, specimen cross-sectional area, and Young's modulus of the rubber, as anticipated from theoretical considerations. The constant of proportionality involved the square root of the energy of adhesion. The value of the energy of adhesion calculated from the proportionality constant was confirmed by an independent peel test.
An NMR Investigation of the Interaction between Carbon Black and Cis-Polyisoprene
Authors: Svensson L. G. , Svanson S. E. 
Published: February 2011

Abstract
Attempts have been made to change the methods of preparation of samples of IR filled with various carbon blacks. Considering experiments where reliable results have been obtained hitherto we have drawn the following conclusions: 1. For solution-mixed and short-milled samples, a large broadening is observed, which is reduced by extraction, heating the samples above 50°C, and by prolonged milling. It is assumed that this broadening is due to interactions of a physical nature. The remaining broadening effect is assigned to irreversible effects of a chemical nature. 2. For dry-milled samples, where prolonged milling is always needed to achieve reasonable mixing, the main part of the broadening effects is not changed by the above treatments. 3. By heating the products to temperatures above 180°C a pronounced broadening develops. We believe that the largest surface interaction is attained by this treatment.
Kinetics of Crosslinking and Network Changes in Natural Rubber Vulcanizates with a Dithiodimorpholine Based Accelerator System
Authors: Bhowmick A. K. , De S. K. 
Published: February 2011

Abstract
Kinetics of crosslinking and network changes in unfilled and filled natural rubber vulcanizates with a dithiodimorpholine based accelerator system have been studied at 150° and 180°C. Results show that addition of HAF black enhances the polysulfidic crosslinks as well as the total crosslinks. This has been explained with the help of Coran's model wherein HAK black increases the rate constants. It is likely that the filler surface prevents desulfuration and undesirable side reactions involving the crosslink precursors. Increase of curing temperature by 30°C lowers the total crosslink density and increases the sulfur inefficiency.
A New Investigation of Tetrahydrofuran-Based Polyether Glycols in Urethane Elastomers
Authors: Pechhold E. , Pruckmayr G. , Robinson I. M. 
Published: February 2011

Abstract
Random copolyether glycols with 50 mole % EO and low cyclic ether content represent novel soft segments for polyurethanes, and have some advantages over the other soft segments as shown in Table V. THF/EO copolyether glycols are easier to handle and to process because they are liquids at room temperature and exhibit lower viscosities and better diol compatibility. Physical properties of polyurethanes made from THF/EO copolyether glycols are comparable to those made from other soft segments; the hydrolytic stability and low temperature behavior are superior to polyester and polycaprolactone glycols, and solvent/oil resistance is better than PTMEG. THF/EO copolyether glycol is a replacement for PTMEG only with reformulation; it could be considered for applications which require better solvent/oil resistance or easier handling and processability.
Elongational Flow in Mixing Elastomer with Carbon Black
Authors: Nakajima N. 
Published: February 2011

Abstract
The mechanism of mixing elastomers with carbon black involves elongational as well as shear deformation. Therefore, elongational measurements on raw elastomers and compounds are important in understanding the processing behavior. In this paper, the definition of elongational flow is discussed, its application to the mixing equipment is examined, and some results from elongational measurements with raw elastomers and a carbon-black-containing compound are presented.
Force-Balance Capillary Rheometry at Low Shear Rates
Authors: Chalifoux J. P. , Meinecke E. A. 
Published: February 2011

Abstract
The validity and accuracy of force-balance rheometry have been demonstrated by comparing data with readily available methods. At low speeds of extrusion the entrance pressure drop accounts for a very small portion of the overall pressure drop. This situation permitted us to show the equivalence between τwa and the true τw derived from equation (5) or the slopes in the Fe−Lb/D graph. Bagley plots confirmed that the effective τw and results from bottom-top dies yield comparable values over a decade of shear rate. Using flow birefringence techniques, Han and Drexler observed an exit effect at shear rates lower than 10 sec−1, but the data obtained with this thermoplastic elastomer indicated that the velocity profile rearranges only when the exit plane is reached. The wall shear stress was also shown to be independent of L/D.
Dynamic Properties of SBS Block Copolymers
Authors: Yang R. M. , Meinecke E. A. 
Published: February 2011

Abstract
A recently developed mechanical test, consisting of a mechanical excitation where small sinusoidal strains are superimposed upon finite static deformation, was applied to a series of SBS block copolymers. The energy loss per cycle for unit volume of material showed a pronounced peak at those strains, where most of the stress-softening during a normal stress-strain cycle occurs. This peak seems to arise from a strain induced change in structure. The original rod-like structure seems to be changed into one resembling independently dispersed spheres, since the increase of the losses with increasing filler content in the plateau region following the peak can be explained with the help of the Einstein-Guth-Gold strain magnification factor. The loss peak is not observed immediately after a previously applied stress-strain cycle but reforms with time, while the stress-softening is permanent. This discrepancy cannot be explained at this time.
Influence of Compression upon the Shear Properties of Bonded Rubber Blocks
Authors: Porter L. S. , Meinecke E. A. 
Published: February 2011

Abstract
Rubber has a stress-strain response to compression-shear loadings that is the same as its stress-strain response to simple shear loadings. However, its load-deflection response to the compression-shear loading is not the same as its simple shear response. In determining the stress-strain relationship of the compression-shear loading from the load-deflection responses, three factors must be considered. First, the compression of the sample gives a lower rubber thickness. After calculating the strain, the lower thickness will give a higher strain than the original thickness at an equal deflection. Second, the compression gives a larger surface area due to bulging of the rubber. The higher area would result in a lower stress than the original area at an equal load. Third, the force that is necessary to compress the rubber block is stored in the rubber. When the rubber is sheared, the shear vector of the compressive force aides in deflecting the rubber. Therefore, the shear force vector would be added to the recorded load to determine the total force needed to shear the rubber. The resulting shear stress would be higher than the shear stress calculated by using the recorded load in calculating the shear stress. With all three factors accounted for, the shear stress-strain of the rubber is the same for the compressed part as it is for the uncompressed part. Therefore, the rubber's shear modulus, the slope of the shear stress-strain curve, has not been affected by the superimposed compression and remains an inherent property of the rubber. When designing a part to be used in a compression-shear application, one can use the shear and compression moduli normally obtained for shear and compression applications. The compression modulus would be used for determining the compressive spring rate and the amount of force used in lowering the shear spring rate. The shear modulus would be used to determine the shear rate by taking into account the geometry changes and the force due to compression.
Structure-Property Studies on a Series of Polycarbonate-Polydimethylsiloxane Block Copolymers
Authors: Tang S. H. , Meinecke E. A. , Riffle J. S. , McGrath J. E. 
Published: February 2011

Abstract
Block copolymers composed of hard and soft segments form an interesting class of materials ranging from thermoplastics to thermoplastic elastomers depending on their composition and/or the size of segments. These materials have attracted much attention in the past decade because by careful tailoring, polymers of desired properties can be obtained. Yet they are thermoplastic in nature and can be processed and even reprocessed thermally. Among the common elastomers that can be used as the soft segment in a block copolymer, polydimethyl-siloxane is of special interest due to its great thermal stability at elevated temperatures and high flexibility at low temperatures. Block copolymers containing polydimethylsiloxane as the soft segment and various thermoplastics such as poly(α-methylstyrene), polystyrene, and polysulfone, etc., as the hard segment, have been synthesized and studied. A group of randomly alternating block copolymers of bisphenol-A polycarbonate and polydimethylsiloxane have also been prepared by in situ polymerization of dichloro-terminated siloxane oligomers and bisphenol-A and phosgene. The properties of these block copolymers as well as those of the others have been discussed to some extent in a general review. This work reports the results of a study on the structure-property relationship of a series of perfectly alternating block copolymers of bisphenol-A polycarbonate and polydimethylsiloxane synthesized via different routes. They were prepared by silylamine-hydroxyl reaction. Slightly less than the stoichiometric quantity of siloxane oligomers was incrementally added to a hydrated solution of the polycarbonate in refluxing chlorobenzene. The reaction can be represented by the simple scheme:
Mechanisms of Ozonation of N,N′-di-(1-Methylheptyl)-p-Phenylenediamine
Authors: Lattimer R. P. , Hooser E. R. , Diem H. E. , Layer R. W. , Rhee C. K. 
Published: February 2011

Abstract
The ozonation products of a common rubber antiozonant, N,N′-di-(l-methylheptyl)-p-phenylenediamine (DOPPD), have been separated by liquid or gas chromatography. Molecular weights of about thirty LC separated components have been measured by field desorption mass spectroscopy. Elemental formulae have been determined by atomic composition mass spectroscopy. Other structural details have been elucidated by electron impact mass spectroscopy and attenuated total reflectance infrared spectroscopy. Two principal mechanisms appear to govern the ozonation of DOPPD. Amine oxide formation leads to observed nitrosoaryl and nitroaryl products. The second major mechanistic pathway is side chain oxidation. This leads to a number of low molecular weight components, including some that contain an amide moiety. A third (minor) mechanistic pathway involves a nitroxide radical intermediate and leads to the formation of a stable dinitrone species. The surface film formed on ozonation of a black loaded natural rubber sheet containing DOPPD has also been examined. The film contains appreciable quantities of unreacted DOPPD and many of the same low molecular weight components as observed in the ozonized liquid antiozonant. It is clear that DOPPD blooms to the rubber surface and acts as a scavenger for ozone. The results are consistent with a combined “scavenger-protective film” mechanism for antiozonant protection.
Analysis of Cured, Filled Elastomeric Compounds by 13C NMR
Authors: Werstler D. D. 
Published: February 2011

Abstract
This paper has discussed the study of cured, filled elastomers by a newly developed 13C NMR method. This method overcomes many of the shortcomings of other methods in that the 13C method is capable of distinguishing nonstandard or experimental polymeric components in an elastomeric blend, a definite advantage for the analyst. Other advantages are that the 13C data are primary, i.e., compositional calibration standards are not necessary once a polymer's 13C carbon resonances have been assigned; the data are accurate and reproducible; the filler (carbon black, TiO2, glass fibers) does not have to be removed prior to the analysis; and, the method is sensitive to low levels of polymer concentration. The superiority of 13C quantitative data over IR data has been demonstrated. Practical examples including nonstandard and/or unique elastomeric components have been discussed.
Ultrafine Recycled Rubber
Authors: Swor R. A. , Jensen L. W. , Budzol M. 
Published: February 2011

Abstract
A technical advance in the size reduction of cured scrap rubber has been achieved by a new process. The performance of products whose particle dimensions are 90% under 20 µm in diameter has been described in this study. When small panicle size rubber made by this process is used to extend high quality compounds, the degree of retention of key properties of the extended compounds surpasses that of compounds extended with conventional recycled materials. Many unexpected product and process improvement characteristics have been reported. In most cases, the properties of the extended compound are close to those of the unextended compound, even at high loading levels. Initial trials using this unique paniculate rubber at up to 30% concentrations in bias-ply passenger tire treads have shown no performance deficiencies. The addition of RR does not require any special processing techniques, mixing cycles, or equipment. Substantial cost savings are possible by extending virgin rubber compounds with ultrafine recycled rubber.
A Fatigue-Life Model of a Rubber Bushing
Authors: Oh H. L. 
Published: February 2011

Abstract
A major performance requirement for a rubber bushing is durability. The model for fatigue life of a bushing given in Equation (4) was derived using an energy balance concept (energy available versus energy required to extend a tear). This model agreed well with test results. A design procedure was developed from the model which gives the optimum insert geometry for maximum bushing life.