bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compression of Rubber Blocks
Authors: Gent A. N. 
Published: February 2011

Abstract
Many features of the compression of rubber blocks can be deduced by means of a simple analytical treatment which, although approximate, appears to give reasonably satisfactory predictions for stiffness and interfacial stresses. The theory has been redeveloped and refined many times; some principal contributions are noted in References 1–14. While the analysis has been frequently repeated, it is interesting to note that what is probably the first, and in some ways the most comprehensive, theoretical discussion, did not refer specifically to rubber blocks; it dealt with the elastic properties of the periodontal membrane in connection with the tightness of teeth. Apart from an extensive review in connection with the use of rubber compression springs for bridge bearings, general results for small compressions of rubber sheets and blocks have not been collected together previously in one easily-available place, as far as I am aware. A review is therefore given here, with some remarks on its limitations. Attention is drawn to the surprisingly large effect of relatively small departures from absolute incompressibity of rubber, and of the use of frictional restraints instead of perfect bonding at loaded surfaces.
Effect of Crosslink Structures on the Fatigue Crack Growth Behavior of NR Vulcanizates with Various Aging Conditions
Authors: Kim Sang Goo , Lee Suck-Hyun 
Published: February 2011

Abstract
The effect of crosslink structures on the fatigue crack growth (FCG) behavior of unfilled and HAF-filled vulcanizates with conventional (Conv), semi-efficient (Semi-EV) and efficient (EV) cure systems, all with similar levels of total crosslink densities, was investigated before and after aging at 100°C in air and in nitrogen. The unfilled vulcanizates before aging did not show differences in the FCG rate through the whole range of tearing energy applied in this study. However, HAF-filled vulcanizates before aging showed some differences in the FCG rate with an order of EV &gt; Semi-EV &gt; Conv in the range of high tearing energy corresponding to the strain levels from 46 to 85%. Heat aging in air results in a higher FCG rate (compared to before aging) due mainly to the changes of the total crosslink density and the crosslink structures. The Conv cure system in unfilled rubber showed a higher FCG rate than the other cure systems since it had the poorest resistance to heat aging at all the aging periods. Also, heat aging of vulcanizates in air gave higher FCG rates than heat aging in nitrogen because of the dominant effect of oxidative degradation on the mechanical fatigue resistance of the rubber. The various vulcanizates after aging at 100°C in air showed that the FCG rate and slopes (between the FCG rate and the tearing energy) were drastically changed at similar critical tearing energy. The slopes of all samples changed at the critical strain levels of around 40–50% over which the classical statistics theory for rubber elasticity disobeys.
Chemical Interaction between Carbon Black and Elastomers — Crosslinking of Chlorosulfonated Polyethylene by Carbon Black
Authors: Roychoudhury A. , De S. K. , De P. P. , Ayala J. A. , Joyce G. A. 
Published: February 2011

Abstract
Surface oxidation of a carbon black leads to an increased elastomer-filler bonding between the chlorosulfonated polyethylene and the carbon black. The increased interaction appears to be related to the increased concentration and reactivity of the oxygen containing sites in the oxidized carbon black, as deduced from the moisture adsorption and thermometric titration results. The bound rubber content is substantially higher for the oxidized carbon black. The reactive surface sites of the carbon black also promote the crosslinking of the elastomer at elevated temperatures.
Study on Dispersion Morphology of Silica in Rubber
Authors: Li Yingbing , Wang M. J. , Zhang Tao , Zhang Fenhou , Fu Ximei 
Published: February 2011

Abstract
A new model of silica's aggregation in rubber, the Hexagon-linking Model, is proposed and tested in this study, using transmitting, scanning and analytical electron microscopy. When wetted in rubber, silica tends to accumulate, by way of hexagonal rings, differently from carbon black; the “wetted” states can be controlled through mixing procedures. The experimental evidence that aggregation of silica (original size of 20 nm) precedes to a final size of 63.8 nm, as compared to a theoretical value of 60 nm, supports the theoretical model. The wetted filler structure can be controlled by the mixing process, and hence desired composite properties can be achieved.
Fatigue of Cord-Rubber Composites
Authors: Lee B. L. , Liu D. S. , Chawla M. , Ulrich P. C. 
Published: February 2011

Abstract
Fatigue failure mechanisms and their dependence on cyclic loading frequency were assessed in the case of a nylon fiber-reinforced elastomer matrix composite representing the actual carcass of bias aircraft tires. Under uniaxial tension, the angle-plied composite specimens were subjected to a considerably large interply shear strain before failure. The composite specimens exhibited infinite fatigue life when stress amplitude was below a threshold level, i.e., fatigue endurance limit. Under cyclic stresses exceeding the endurance limit, localized damage in the form of fiber-matrix debonding and matrix cracking was formed and developed into the delamination eventually leading to gross failure of the composite. The process of damage accumulation was accompanied by a continuous increase of cyclic strain as well as temperature. Fatigue lifetime and the resistance to damage accumulation of aircraft tire carcass composite were strongly influenced by cyclic frequency. The use of higher frequency resulted in shorter fatigue lifetimes at a given stress amplitude and lower endurance limit. The extent of xdynamic creep at gross failure, which is defined as the increase of cyclic strain beyond initial elastic deformation, was roughly independent of stress amplitude under the frequency of 1 Hz, but decreased with higher stress amplitude when the frequency was raised to 10 Hz. Obviously a critical level of dynamic creep exists for gross failure of the composite and this level appears to be independent of the stress amplitude at low frequency. When the frequency is sufficiently high, heat generation due to hysteretic loss is expected to degrade the materials. In this situation, the critical level of dynamic creep for gross failure seems to be reduced by the loss of matrix flexibility as well as fiber-matrix bonding strength, with the degree of reduction becoming greater under higher stress amplitude.
Precipitation of Silica-Titania Mixed-Oxide Fillers into Poly(Dimethylsiloxane) Networks
Authors: Wen Jianye , Mark James E. 
Published: February 2011

Abstract
Previous studies have demonstrated techniques by which model elastomers prepared by end linking poly(dimethylsiloxane) (PDMS) chains can be reinforced by the in-situ precipitation of silica from a base-catalyzed sol-gel conversion of tetraethoxysilane (TEOS). The present investigation extends this technique to silica-titania mixed oxides through the sol-gel conversion of mixtures of TEOS and titanium n-butoxide. The elastomeric networks reinforced by this novel mixed filler were found to have very good mechanical properties, and swelling equilibrium measurements indicate that there is good adhesion between the SiO2-TiO2 filler and the elastomeric matrix. Compared with networks containing silica alone, the networks containing silica-titania mixed oxides had somewhat better combinations of high modulus and good extensibility. The particle size was typically several hundred A˚ in diameter but was found to be inversely dependent on the crosslink density of the PDMS network. Thus, larger particle sizes can be obtained at lower crosslink densities (which give larger network mesh sizes). The distribution of particle sizes is relatively narrow, and there is very little particle aggregation. The presence of in-situ silica-titania mixed oxides can also increase the onset temperature for degradation of the PDMS host matrix.
Effects of Alkylation of Silica Filler on Rubber Reinforcement
Authors: Ou Yu-Chun , Yu Zhong-Zhen , Vidal A. , Donnet J. B. 
Published: February 2011

Abstract
Rubber reinforcement of silicas with different surface alkylation have been evaluated by studies of NH3-modified swelling, swelling volume fraction, stress-strain tests, and scanning electron microscopy. Effects of silica alkylation on filler dispersion has been explained on the basis of surface energy and acid-base interactions. Bound rubber reductions have been explained according to acid-base interactions and/or physical entanglements. Hysteresis losses have been interpreted based on the reductions of polymer-filler and filler-filler interactions. The results show that the extent of reinforcement in NR and SBR vulcanizates is reduced when the silicas are alkylated, especially in the case of the hexadecyl group. However, in NBR vulcanizates the alkylation seems to have less influence on the reinforcement characteristics of the silica.
Preparation and Characterization of Crystalline 3,4-Polyisoprene
Authors: Hsu W. L. , Halasa A. F. 
Published: February 2011

Abstract
Gel-free, semi-crystalline polyisoprenes containing 70–81% 3,4 units were prepared using an improved iron catalyst. A partially hydrolyzed triisobutylaluminum was used as the reducing agent for the improved catalyst, which allowed the title polymers to be prepared in aliphatic solvents at fast rates.
An Elastomeric Ejection System
Authors: Choi I. S. , Roland C. M. , Bissonnette L. C. 
Published: February 2011

Abstract
The ability of elastomers to store large quantities of energy, which can subsequently be recovered very quickly, makes them attractive materials for propulsion devices. Recently the U.S. Navy has developed a torpedo ejection system based on an elastomeric mechanical capacitor. The criteria governing selection of a material for this application include high elastic energy, sufficient fatigue life, minimal creep, and resistance to deterioration by seawater. This paper describes various approaches to obtaining these material properties.
Large Strain Viscoelastic Constitutive Models for Rubber, Part I: Formulations
Authors: Johnson A. R. , Quigley C. J. , Mead J. L. 
Published: February 2011

Abstract
Constitutive models for large strain isothermal viscoelastic deformations of rubber are reviewed. The models discussed are for materials which have separable long and short term stresses, and for which the short term stresses have separable time and strain effects. They include the history integral model, an internal stress variable model, an internal stretch variable model, and an internal solid model. The internal stretch variable model and the internal solid model were motivated by molecular descriptions of rubber viscoelasticity. The material tests required to determine the constants for these large strain models are discussed. The classical problem of determining a rubber energy density function, used to describe both the long term and short term energy in these models, is reviewed. A method to assure Drucker stability, a commonly overlooked issue, is presented for experimentally determined Rivlin energy density function expansions. Also, an improved method for determining the coefficients of a Prony series, which defines a material's relaxation time spectrum, from experimental relaxation data is presented.
Quantitative Fractography of Rubber by Image Processing Technique
Authors: Ganesan L. , Bhattacharyya Pritimoy , Bhowmick Anil K. 
Published: February 2011

Abstract
In this paper, an image processing technique to quantitatively analyze abraded, torn and fatigue failed surfaces is described. The image surfaces were represented in terms of a closed set of orthogonal polynomials. The significant orthogonal effects were measured and combined to represent the local texture, called pronum. The frequency of occurrence of the pronums is the prospectrum, a global descriptor. Various statistical parameters were calculated from the prospectrum and correlated to the ridge spacings on abraded surfaces. The statistical closeness between various textured surfaces was also quantified. Using the image processing technique, the laborious procedure involved for quantification especially of irregular microfeatures has been shown to be overcome. Author to whom correspondence should be addressed.
Formation of Surface Structure in Vulcanizates and Surface Structure Changes in Air
Authors: Mori Kunio , Kanae Kentaro , Hirahara Hidetoshi , Oishi Yoshiyuki 
Published: February 2011

Abstract
The formation theory of surface structure during vulcanization was developed on the basis of an interfacial concept. The theory showed the chemical compositions of polar and nonpolar components on the vulcanizate surface to be determined as an excess interfacial free energy between rubber compounds and molds decreases. The surface free energies of molds reflected clearly the corresponding surface free energy of vulcanizates prepared from copolymers and polar polymers. Nonpolar polymers were not influenced by the surface free energies of molds. The surface free energies of vulcanizates decreased slightly with the concentration of network chains owing to the entropy of rubber segments. The surface free energies of molds affected the chemical compositions at the topmost surface region to the upper surface region on vulcanizates. NBR vulcanizates with high surface free energy increased the contact angle of water after standing in dry air. In the dry air environment, topmost surface layer nitrile groups were buried in the bulk of NBR vulcanizates and butadiene units subsequently overturn to the topmost, layer. In this case, the vulcanizate surface chemical composition was influenced only at the topmost surface region. ESCA spectra N1s peak intensities on NBR vulcanizates was consistent with these observation.
Effect of Porosity on Mechanical Properties of Rubber
Authors: Kasner A. I. , Meinecke E. A. 
Published: February 2011

Abstract
Cylindrical samples, with different shape factors and levels of porosity, were prepared from a model EPDM compound and tested in compression. The modulus was reduced considerably with the introduction of porosity, especially when the shape factor was high. The stress-strain curves showed nonlinearity which depends on the shape factor and porosity level, and is related to bubble closure. The apparent modulus of bonded blocks was found to consist of two components: homogeneous compression modulus and a hydrostatic contribution. The first was obtained by compression of blocks between lubricated compression plates. It can be predicted from analytical expressions adapted from composite theories for high density foams in tension. The second arises from the pressure buildup inside the bonded blocks and depends on the shape factor and the porosity level. These moduli, after correcting for compressibility, were used to develop approximate relations describing the stress-strain curves of porous bonded blocks. The stress-strain curves of samples with different shape factors and levels of porosity could be predicted from experimental data or FEA estimates.
Novel Ultrasonic Technology for Devulcanization of Waste Rubbers
Authors: Isayev A. I. , Chen J. , Tukachinsky A. 
Published: February 2011

Abstract
A novel patented process and several reactors have been developed for devulcanization of waste rubbers. The technology is based on the use of the high power ultrasonics. The ultrasonic waves of certain levels in the presence of pressure and heat rapidly break up the three-dimensional network in crosslinked rubbers. The devulcanized rubber can be reprocessed, shaped and revulcanized in much the same way as a virgin rubber. The first laboratory reactor has been scaled up to pilot-plant level by the National Feedscrew and Machining, Inc. Various devulcanization experiments were carried out with model styrene-butadiene rubber (SBR) and with ground rubber tire (GRT). Curing behavior, Theological properties, and structural characteristics of rubbers devulcanized at various processing conditions were studied, as well as mechanical properties of revulcanized rubber samples. A possible mechanism of the devulcanization is discussed. The performed measurements indicate that the rubbers are partially devulcanized, and the devulcanization process is accompanied by certain degradation of the macromolecular chains. In spite of these observations, the processing conditions are identified at which the retention of the mechanical properties is found to be good. A further work is in progress to find the optimal conditions of devulcanization and to improve the selectivity of the process towards breaking up the chemical network only.
Molecular Weight Defined in Sol-Gel Analysis and Its Application to Evaluate Branching
Authors: Ahagon Asahiro 
Published: February 2011

Abstract
It is considered that many “linear” polymers are actually branched; however, it is difficult to show this with ordinary methods for an arbitrarily chosen polymer. Branching can be regarded as premature crosslinking below the gel point. Attention is then paid to the well-established Charlesby-Pinner Equation used for sol-gel analysis in crosslinking studies. It contains the number average degree of polymerization before crosslinking as a parameter. The molecular parameter is considered here to be that of the virtual linear polymer which would be obtained by unlinking any branch points contained in the polymer. Evidence is shown to support this. It is then possible to estimate the total number of linear components on an average molecule of a branched polymer by taking the ratio of the number average molecular weight measured by two methods, i.e., sol-gel analysis and an ordinary method like GPC. Further information about the branching structure can be obtained by additional measurements of effective crosslink density for a series of polymers obtained from similar polymerization processes.
Bound Rubber and Elastomer-Filler Interaction
Authors: Meissner B. 
Published: February 2011

Abstract
The statistical theory of bound rubber and the polymer-filler gel formation theory are shown to offer a satisfactory quantitative description of a set of experimental bound-rubber data recently obtained by Wolff, Wang, Tan (Rubber Chem. Technol. 66, 163 (1993)) on SBR compounds filled with 17 furnace blacks covering the whole range of rubber grades. The observed decrease of bound-rubber content per unit of interfacial area with increasing loading and/or specific surface area of carbon black is explained by the theory as being due to the statistical nature of the adsorption process. A correlation was found to exist between specific surface activity of filler D (adjustable parameter of the theory, number of active sites per unit surface area) and filler structure, the latter being characterized by the difference between DBP absorption and crushed DBP absorption. Also, D was found to increase with loading of a high-structure black. The two effects are ascribed to filler aggregates breakdown during mixing, which leads to a new active surface formation for polymer bonding.
Scanning Transmission Imaging of Elastomer Blends Using an Unmodified Conventional Scanning Electron Microscope
Authors: Cudby Paul E. F. , Gilbey Barry A. 
Published: February 2011

Abstract
A novel method for carrying out scanning transmission electron microscopy on a standard scanning electron microscope is described. This method involves the addition of a specially fabricated mount and is accomplished without carrying out any form of modification on the microscope. The method is compared to more conventional microscopy techniques and examples are given showing the advantages of this system.
Hydroxyl-Terminated Polybutadiene Telechelic Polymer (HTPB): Binder for Solid Rocket Propellants
Authors: Ajaz A. G. 
Published: February 2011

Abstract
This paper presents a review of hydroxyl-terminated polybutadiene telechelic polymer (HTPB) with emphasis on its preparation, properties, end group modifications, hydrogenation, role as polyurethane precursors and binders for solid rocket propellants.
Nomenclature of Polymeric Materials
Authors: Fox Robert B. 
Published: February 2011

Abstract
The purpose of this brief review is to aquaint the authors and readers of Rubber Chemistry and Technology with the essentials of polymer nomenclature. To ensure quality communication, it is important that a common language be utilized that is understood, not only by those in the rubber and elastomers field, but by anyone in related areas of polymer science and technology as well. Traditional and trade names of polymeric materials often have time-honored meanings but are obscure or incomplete and frequently fail to convey reasonably accurate information. Many polymer and chemical names are at best ambiguous, but are easily correctable. The methods outlined here have been adopted by the Commission on Macromolecular Nomenclature of the International Union of Pure and Applied Chemistry (IUPAC); their use in Rubber Chemistry and Technology is strongly recommended. Additional details will be found in the appropriate IUPAC publications. Note that for the purposes of this paper italics are generally used to set-off “names” for emphasis. However, when naming polymers for RC&T, Roman characters should generally be used with only the ‘connectives’ or ‘prefixes’ appearing in italics (see Table I). By convention, in manuscripts text that is to be printed in italics should be underlined.
Solid-State C-13 NMR Studies of Vulcanized Elastomers XIII. TBBS Accelerated, Sulfur-Vulcanization of Carbon Black Filled Natural Rubber
Authors: Mori Makio , Koenig Jack L. 
Published: February 2011

Abstract
Solid state C-13 NMR has been used to compare the chemistry of accelerated vulcanization of natural rubber using N-t-butyl-2-benzothiazole sulfenamide in the presence and absence of carbon black. The carbon black filler has an influence on the vulcanization chemistry in addition to its accepted role in reinforcment and stabilization. The basic network structure formation is modified to the extent that crosslink desulfurization from poly to monosulflde structures occurs earlier in the cure in the presence of carbon black. No main chain scission or double bond migration was detected.