bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sulfur Vulcanization of Simple Model Olefins Part III: Vulcanization of 2,3-Dimethyl-2-Butene in the Presence of Different Metal Complexes
Authors: Versloot P. , Haasnoot J. G. , Reedijk J. , van Duin M. , Put J. 
Published: February 2011

Abstract
The mechanism of the sulfur vulcanization of rubber was studied by using 2,3-dimethyl-2-butene (C6H12) as a simple, low-molecular model alkene. Only equivalent allylic positions are present in this alkene. Treating C6H12 with a mixture of ZnO, S8 and the accelerator tetramethylthiuramdisulfide at 140°C yields a mixture of addition products (C6H11—Sn—C6H11). Similar reactions in the presence of various metal oxides instead of zinc oxide show poor vulcanization results. Experiments with various metal dithiocarbamate complexes show a reactivity towards vulcanization in the following sequence: Zn(detc)2&gt;Cd(detc)2&gt;Cu(detc)2&gt;Pb(detc)2&gt;Zn(dmtc)2&gt;Ni(detc)2&gt;Cu(dmtc)2.
3D Morphological Characterization of Carbon-Black Aggregates Using Transmission Electron Microscopy
Authors: Gruber Tyler C. , Zerda T. W. , Gerspacher Michel 
Published: February 2011

Abstract
A three-dimensional modeling technique is used to characterize the structure of carbon-black aggregates. The relative positions of individual particles in aggregates are determined using transmission electron microscopy (TEM). Data are acquired from two-dimensional projections taken with the aggregates at two different orientations with respect to the electron beam. Computerized aggregate models are generated using data from TEM projections in our reconstruction algorithm. Inspection of these models shows that their projections very closely replicate the TEM micrographs. Quantitative analysis of the aggregate models reveals that aggregates generally exhibit anisotropy, in the form of a reduction of aggregate breadth, or “flatness,” in one direction. The flat sides tend to align preferentially, along the plane of the TEM sample grid. The dimensions for each aggregate with respect to its best-fitting plane of flatness are determined, and are related through a “flatness index.”
Analysis of the Mechanism of N-t-Butyl-2-Benzothiazole Sulfenamide Accelerated Sulfur Vulcanization of cis-Polyisoprene
Authors: Krejsa M. R. , Koenig J. L. , Sullivan A. B. 
Published: February 2011

Abstract
Results of previously published work involving network analysis and accelerator intermediate analysis of cis-polyisoprene were compared to help correlate and rationalize network/chemistry relationships. Both classical chemical probe network analysis and further NMR measurements (DEPT analysis) were used as necessary to verify NMR peak assignments. Furthermore, samples of the conventional formulation were vulcanized in the absence of zinc oxide and stearic acid to help elucidate the role of zinc in the vulcanization process. Polysulfidic dibenzothiazole accelerator intermediates were proposed to produce allylic substituted cis-polysulfides both with and without double bond migration, while zinc polysulfidic dibenzothiazole accelerator intermediates were proposed to produce allylic cis and trans polysulfides substituted structures with no double bond migration. Polysulfidic substitution on the isoprene methyl carbon was shown to result from exchange reactions during network maturation. The network-chemistry relationships were compared with earlier mechanistic studies and several points of agreement were noted.
The Application of Small Angle Neutron Scattering to Elastomers
Authors: Lohse David J. 
Published: February 2011

Abstract
The last twenty years have seen a dramatic increase in the application of small angle neutron scattering to polymer science. In this review the use of SANS to study elastomers and elastomeric systems has been summarized. This has focused on those applications most significant to the understanding of rubber. These have included the dimensions of polymer chains in the bulk melt state, the miscibility of polymer blends, the structure of block copolymers, and the nature of crosslinked networks. The information that has been obtained so far has cleared up many of the outstanding questions about elastomers, and one can only expect that this use will increase in the future and will yield a wealth of useful information.
Elastomers for Biomedical Applications
Authors: McMillin Carl R. 
Published: February 2011

Abstract
Over 11 percent of the gross national product of the U.S.A. is currently being spent in areas related to health care. Medical applications of polymers account for about six percent of the dollar sales of processed polymer products, or over three billion dollars annually. Medical devices, consumables, and their packaging are estimated to have used 2.3 billion pounds of polymers in 1992. This paper describes research and development within the biomedical elastomer and rubber segments of this market. Elastomers used in biomedical applications can be roughly divided into three groups; the commodity elastomers that happen to be used in the biomedical field, medical grades of elastomers that are certified for food contact or for short-term physiological contact, and a small group of elastomers that are suitable for longer-term physiological contact or implantation. Although significant from a national perspective, the many uses of commodity elastomers in the medical field will not be discussed in this paper. Some of the additional material requirements that occur when elastomers are employed in contact with biological systems include: more stringent quality control, higher purity, more controlled and cleaner manufacturing facilities, and much more additional paperwork—including information so that traceability is maintained. In most cases, the elastomers must have a degree of biocompatibility. Other specific features may also be needed, such as the ability to be sterilized by gamma irradiation or steam autoclave. Materials that are manufactured with these ends in mind are often called “medical grade.” The number of candidate materials for the high profile, implantable speciality elastomers market is considerably smaller. These elastomers must survive much more rigorous biocompatibility testing and are sometimes optimized for specific properties such as blood compatibility, extraordinary fatigue strength, or controlled biodegradability. Because there are relatively few rubbers or elastomers that are suitable for use in vivo, it is particularly significant that several of the most important of these have been withdrawn from the market because of perceived product liability issues.
Penetration of Silicone Polymers into Silica Agglomerates and Its Influence on Dispersion Mechanism
Authors: Bohin F. , Manas-Zloczower I. , Feke D. L. 
Published: February 2011

Abstract
The dispersion of silica agglomerates suspended in silicone fluids undergoing simple shear flows has been studied. Two different breakup mechanisms, denoted “rupture” and “erosion” have been observed. These two breakup modes produce significantly different fragment size distributions. Penetration of the suspending fluid into the silica agglomerate was found to affect the mode and the conditions necessary for dispersion of the agglomerate. Silica agglomerates totally penetrated by silicone fluids resist dispersion much better than unpenetrated agglomerates. The kinetics of matrix penetration was modeled on the basis of capillary forces driving the penetration and viscous effects resisting it. Agreement of this model with experimental observations is excellent.
Viscoelastic Effects in Cutting and Tearing Rubber
Authors: Gent A. N. , Lai S-M. , Nah C. , Wang Chi 
Published: February 2011

Abstract
Measurements of cutting resistance have been made for a crosslinked styrene—butadiene copolymer over a wide range of cutting speeds and temperatures. A characteristic fracture energy was determined using the procedure of Lake and Yeoh. A lower limit, about 150 J/m2, was obtained at low cutting speeds. This value is significantly higher than the threshold tear strength, about 30 J/m2, due to roughness of the blade tip. The tear resistance increased dramatically as the test temperature was lowered, by a factor of over 1000X, whereas the cutting resistance remained largely unchanged over a considerable temperature range. Much of the enhanced tear resistance at low temperatures is therefore attributed to increasing roughness of the tear tip, the intrinsic strength remaining approximately constant. As the tear strength followed a WLF temperature dependence closely, roughening of the tear tip is associated with viscoelastic effects. Higher cutting resistance was shown by a sulfur vulcanizate, but carbon black had no additional effect. Variations in tensile strength with rate of elongation and temperature are discussed in terms of tearing from an initial edge flaw.
Reactive Compounds for Effective Utilization of Silica
Authors: Mandal Swapan Kumar , Basu Dipak Kumar 
Published: February 2011

Abstract
Bis(diisopropyl)thiophosphoryl disulfide (DIPDIS), diisopropyl thiophosphoryl-N-oxydiethylene sulfenamide (DIPTOS), diisopropyl thiophosphory)-N-oxydiethylene disulfide (DIPTOD), diisopropyl thiophosphoryl-2-benzothiazole monosulfide (DIBMS), diisopropyl thiophosphoryl-2-benzothiazole disulfide (DIBDS) and bis(diisopropyl)thiophosphoryl monosulfide (DIPMS) react with silica and generate isopropyl alcohol as a result of rubber-DIPDIS-silica interactions. Increasing the amount of DIPDIS in the system brings about a corresponding increase in silica-rubber coupling, resulting in enhancement of ΔTf−ΔTg modulus and tensile strength. The vulcanizates containing 14 mmol DIPDIS and 35 phr of silica exhibit highest torque and tensile strength. This is commensurate with the optimum loading derived from Lee's method. The synergistic system containing DIPDIS and N-oxydiethylene-2-benzothiazole sulfenamide (OBTS) provides a very useful combination of accelerators. The vulcanizates obtained from this system exhibit highest torque and tensile value even at a lower concentration of accelerator (DIPDIS : OBTS = 7: 3.5) for the same loading of silica (35 phr).
The Correlation among Vulcanizate Properties Using Computer Aided Design
Authors: Zhengji Jin , Jianming Gu , Weidong Liu , Shiqi Zhang 
Published: February 2011

Abstract
The concepts of optimizability and correlative matrix are proposed and evaluated as a means of correlating the mechanical properties of rubber compounds — elongation at break, tensile strength, set, elastic resilience, tear strength, abrasion loss, aging coefficient, fatigue life, crack initiation, and aged stress — with the rubber formulation variables —NR/SBR/BR composition, accelerator level, sulfur level, antioxidant level, antiozonant level, silica level, and extender oil level.
Oxidation of Elastomers in Aqueous Environments
Authors: Riaya Ascencion , Shaw Montgomery T. , Garton Andrew 
Published: February 2011

Abstract
Crosslinked 1,4-poly butadiene (BR) and styrene-butadiene rubber (SBR) were oxidized in various ionic environments (water, neutral salt solutions, acidic and basic buffers). The acceleration of oxidation when the elastomer was immersed in neutral and basic aqueous solutions, compared to dry air, is consistent with nucleophilic attack by peroxy anions on polymer hydroperoxides to give free radicals capable of initiating further oxidation. Acidic solutions retarded oxidation, compared to air, presumably because of decomposition of hydroperoxides to nonradical products. This phenomenon is in addition to the well-known effects of extraction of antioxidants by liquid media, and the accelerating effect of transition metal ions. The accelerating effect of basic solutions was greatest at the polymer surface, providing an inexpensive route to surface modification of elastomers. As an example, scrap rubber crumb was treated with aqueous alkaline hydrogen peroxide solution or sodium hypochlorite solution and evaluated as an impact modifier for brittle polymers.
Method for Estimating the Chemical Crosslink Densities of Cured Natural Rubber and Styrene-Butadiene Rubber
Authors: Lee Shirley , Pawlowski Henry , Coran A. Y. 
Published: February 2011

Abstract
Chemical crosslink densities of gum and carbon black-filled natural rubber (NR) and styrene-butadiene rubber (SBR) were estimated by using a newly developed rheometer. The rheometer is the Rubber Process Analyzer (RPA 2000) which is designed specifically to measure dynamic properties such as shear storage modulus G′ and shear loss modulus G″ in cured and uncured rubber. It was found that the differences between the G′ values of dicumyl peroxide-cured NR and those of uncured samples yielded estimates of the crosslink densities which were nearly the same as the values inferred by chemical analysis. For TMTD-cured SBR, the same procedure yielded estimates of chemical crosslinks very close to those estimated by a tensile stress-strain method and by NMR. In addition, accelerated sulfur-cured natural rubber was also investigated. The agreement between the crosslink densities of these stocks determined from G′ values and from a solvent-swelling method was very good.
Failure Properties of Natural Rubber Double Networks
Authors: Santangelo P. G. , Roland C. M. 
Published: February 2011

Abstract
When measured parallel to the curing deformation, double networks of natural rubber have a higher modulus than single networks of equal crosslink density. The difference is greater at higher strains. Despite the higher modulus, the mechanical fatigue lifetimes of double networks were found to be as much as a factor of ten higher than for conventionally crosslinked NR. The double network's tensile strength, on the other hand, was slightly lower. In contrast to these results, the modulus and tensile strength in the direction transverse to the curing strain are minimally affected by the presence of a composite network.
Phase Separation Dynamics of Blends of Telechelic Epoxy Terminated Polybutadiene and Maltene
Authors: Yamamoto Tsunehiro , Kyu Thein 
Published: February 2011

Abstract
Thermally induced phase separation in a mixture of telechelic epoxy terminated polybutadiene (ETPB) and maltene has been studied by means of time-resolved light scattering and optical microscopy. Maltene, consisting of various hydrocarbon derivatives, was extracted from asphalt with n-heptane and isolated by centrifugation. The cloud point studies of the ETPB/maltene mixture showed an upper critical solution temperature (UCST) which is thermally reversible. Several deep temperature quench experiments were conducted at an off-critical composition (27/73 ETPB/maltene) from a single phase (80°C) to a two-phase region (27, 29, 31 and 33 °C). The time-evolution of the structure factor for the late stage of spinodal decomposition (SD) was analyzed in the framework of nonlinear and dynamical scaling laws. The reverse quench experiments were also undertaken to elucidate the phase dissolution process.
Nonlinear Elastic Analysis of the Adhesive Strength between Rubber-Like Materials and Rigid Surfaces
Authors: Sun Shochang M. , Chang W. Victor 
Published: February 2011

Abstract
A nonlinear elastic finite element analysis of the adhesive strength between rubber-like materials and rigid surfaces has been conducted based on fracture mechanics principles. The finite element model is an elastomer half sphere adhering to a rigid flat surface. An analytical solution for the system was first developed by Johnson, Kendall and Roberts (JKR) in 1971, which agrees well with experimental data for small contact area. The objective of this paper is to elucidate the relationship between the adhesive fracture energy, tensile loads and debonding process of the system when the contact area is large. A general analysis procedure for nonconforming adhesion-contact problem has been established in this study, which allows us to determine the adhesive fracture energy from measurements of the final pull-off force Pc or the zero-load contact radius α0. Our results agree well with JKR's prediction when the zero-load contact radius is less than 25% of the radius of the sphere. However, as the contact radius increases, the debonding process deviates from JKR's prediction.
Physical Adsorption of Polymers on Disordered Filler Surfaces
Authors: Heinrich Gert , Vilgis Thomas A. 
Published: February 2011

Abstract
The problem of polymer adsorption on carbon black surfaces is considered within the concept of disorder-induced localization of polymer chains on disordered or fractal surfaces. The model describes how physical adsorption properties are enhanced compared to the adsorption on a flat surface. The difference is based on the configurational entropy which is less restricted in the disordered case than in the flat case. In fact, the surface of the carbon black particles is disordered over certain length scales and several experimental techniques have shown that the particle surface is fractal. This fractal nature can be quantified by the surface spectral density and the noninteger fractal surface dimension. As a main consequence, the coupling between filler and polymer is caused by entanglements formed between tightly adsorbed bound rubber on the filler surface and the bulk rubber far removed from the surface. The corresponding density of couples is estimated for several filled polymer networks using tensile test results. The stress-strain relations used are based on a new rigorous molecular-statistical model of filled polymer networks with quenched topology that includes the entanglements within the mobile rubber phase (configurational tube-model).
Effect of Precipitated Silica Physical Properties on Silicone Rubber Performance
Authors: Okel Timothy A. , Waddell Walter H. 
Published: February 2011

Abstract
Nitrogen BET surface area is a highly accurate predictor of the physical performance of silica-filled and silica and carbon black-filled, cured organic rubber compounds. The effectiveness of predicting performance of a high-temperature-vulcanized, high-consistency silicone rubber, based on precipitated silica physical properties, is presented. Correlation and regression analyses were performed for twenty-five silica physical properties and fourteen silicone rubber performance characteristics. Silica properties studied included measurements of surface area, structure, impurities, particle size, pH and adsorbed moisture. Silicone rubber performance included measures of processing, curing, reinforcement, resiliency, stress whitening, color and clarity. The present study confirms that no single silica physical property can predict silicone rubber performance. A combination of surface area, oil absorption, particle size, pH, adsorbed moisture, residual sodium and/or residual salt can qualitatively predict the physical performance of high-temperature-vulcanized, high consistency, precipitated silica-filled silicone rubber.
Large Strain Viscoelastic Constitutive Models for Rubber, Part II: Determination of Material Constants
Authors: Quigley Claudia J. , Mead Joey , Johnson Arthur R. 
Published: February 2011

Abstract
A method for determining material constants in large strain viscoelastic materials was demonstrated for a highly saturated nitrile rubber. Material constant selection was based on viscoelastic stress relaxation data at small and large strains, under both tension and compression, and was constrained to assure Drucker stability. Assuming that the viscoelastic strain energy function was both time and strain separable, a Prony series was constructed for the time dependent material constants. For comparison, four different Prony series were developed from collocation methods and a nonlinear regression analysis, each separately based on either large or small tensile strain relaxation data. In addition, a final Prony series was constructed from dynamic data. These Prony series were included in this comparison to judge their ability to predict both large and small strain material behavior. Finite element analyses of large and small step-strain relaxation tests and a single cycle hysteresis loop at large deformations were performed for each set of Prony series. The results were then compared to experimental behavior. The Prony series based on the constrained method accurately predicted step-strain relaxation behavior at all strain levels, for both tension and compression. The finite element results for the other Prony series show that large strain material behavior was best predicted by those Prony series based on large strain material behavior. Similar findings were found for small strain material behavior. The constrained Prony series and the two large strain based Prony series best modeled the experimental hysteresis loop.
Dynamic-Mechanical Properties of Tin-Coupled SBRs
Authors: Sierra C. A. , Galán C. , Gómez Fatou J. M. , Quiteria V. Ruíz Santa 
Published: February 2011

Abstract
The interaction between rubber and carbon black in compounds for road tire treads has been analyzed by using mechanical and dynamical measurements in three cured compounds based on SBRs. The rubbers were prepared in solution by anionic polymerization, and coupled with tin compounds in which the carbon-tin bond at the end of the chain may correspond to styryl or butadienyl terminations. The interaction parameter, defined by the ratio of mechanical and dynamic terms, has been used for the first time for the evaluation of the compounds. The SBRs with tin-butadienyl bonds exhibit an improved interaction with the filler, with increasing tin content.
A New Method to Hydrogenate Nitrile Rubber in the Latex Form
Authors: Singha Nikhil K. , Sivaram S. , Talwar S. S. 
Published: February 2011

Abstract
A water soluble analog of Wilkinson catalyst — chloro-tris-(sodium diphenylphosphino-benzene-m-sulfonate) rhodium(I), CAS 67178-14-7, i.e. RhCl(DPM)3— has been found to hydrogenate NBR latex. More than 60 mol% hydrogenation can be achieved at 75°C and 1 atmosphere hydrogen pressure. Hydrogenation was accompanied by an increase in gel content of the latex.
Mechanism of Carbon-Black Reinforcement of Rubber Vulcanizate
Authors: Kawabata Sueo , Yamashita Yoshihiro , Ooyama Hajime , Yoshida Shuichi 
Published: February 2011

Abstract
The mechanism of reinforcing rubber with carbon black particles is investigated by comparing the strain energy density functions of pure and reinforced rubbers. Finite deformation biaxial extension experiments are used to measure the strain energy density. The functional form of the reinforced system, which has been proposed by Kawabata, is examined and its validity was confirmed over a temperature range of −20°C to 80°C. The functional form is: W(I1,I2)=CT(I1−3)+β(I1,I2)+γ(I1), where I1 and I2 are the invariants of the deformation tensor. Parameter C is a constant and T is the temperature. The reinforcement effect on W appears as the γ function which is not affected by temperature. The results are analyzed with respect to a network mechanical model consisting of molecule bundles connecting carbon-black aggregates. The function W is calculated and it is shown that the functional form of Wis very similar to that of the reinforced rubber.
Fractal Analysis of Commercial and Pyrolytic Carbon Blacks Using Nitrogen Adsorption Data
Authors: Darmstadt H. , Roy C. , Kaliaguine S. , Sahouli B. , Blacher S. , Pirard R. , Brouers F. 
Published: February 2011

Abstract
The surface fractal dimension of commercial rubber-grade carbon blacks and of pyrolytic carbon blacks (CBp) was determined using nitrogen sorption data. The CBp were produced by vacuum pyrolysis of used tires at different temperatures and pressures. Commercial carbon blacks and CBp obtained at low pyrolysis pressures have a similar fractal dimension of the surface (Ds) or roughness. CBp produced at higher pyrolysis pressures have a smaller fractal dimension than commercial grades, suggesting a smoother surface. Complementary SIMS and ESCA investigations showed that the decreasing fractal dimension with increasing pyrolysis pressure is due to the formation of carbonaceous deposits on the CBp from the pyrolyzed organic material.