bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Frequency and Amplitude Dependence of the Payne Effect: Theory and Experiments
Authors: Lion A. , Kardelky C. , Haupt P. 
Published: February 2011

Abstract
In this paper, we develop a physical approach to represent the Payne effect which is observed in filler-reinforced elastomers. The starting point for the constitutive model is the well-known theory of linear viscoelasticity, where the stress is a linear functional of the deformation history. Since the corresponding relations are unable to describe any kind of amplitude dependence, we introduce a nonlinearity into the model. To this end, we replace the physical time, t, by a modified time scale, z, which is a functional of the deformation history. This approach was originally introduced by Valanis in the context of rate-independent plasticity and applied in a modified form; for example, by Haupt and Sedlan to represent process-dependent relaxation properties of rubber. The modified time, z, is a monotonic function of the physical time, t, and can be interpreted as an intrinsic time scale of the material. The rate of this time scale is non-negative and depends on the process history. We propose a constitutive relation for the variable z(t), which is driven by a fractional time derivative of the deformation, calculate analytical expressions for the storage and dissipation moduli and show that such phenomena as the frequency and the amplitude dependence, observed in experiments, are well represented.
The Mechanics and Mechanism of the Carbon Black Reinforcement of Elastomers
Authors: Fukahori Yoshihide 
Published: February 2011

Abstract
The author proposes a new concept, including a model and theory of the carbon black reinforcement of elastomers, based on stress analysis. Two assumptions are introduced: first, that there are very few or no chemical crosslink in the interface layer of carbon particle and matrix elastomer; and, second, that crazing or a craze-like phenomenon takes place within the interface layer. The deformable character of the interface layer depending on the magnitude of extension will realize the dramatic improvement of elastomers over a wide range of extension. At present time, although there is no direct experimental evidence to prove the assumptions, such assumptions just provide a reasonable interpretation of the carbon black reinforcement of elastomers.
Fracture Mechanics and its Application to Failure in Rubber Articles
Authors: Lake G. J. 
Published: February 2011

Abstract
The basis of the fracture mechanics approach that has been developed for elastomers and the range of phenomena, from tearing to cavitation, to which it has been applied are briefly reviewed. The application of the approach to service and related problems is then considered in somewhat more detail, with particular reference to groove cracking in tires and laminate failure studies.
Sulfur Vulcanization of Natural Rubber for Benzothiazole Accelerated Formulations: From Reaction Mechanisms to a Rational Kinetic Model
Authors: Ghosh Prasenjeet , Katare Santhoji , Patkar Priyan , Caruthers James M. , Venkatasubramanian Venkat , Walker Kenneth A. 
Published: February 2011

Abstract
The chemistry of accelerated sulfur vulcanization is reviewed and a fundamental kinetic model for the vulcanization process is developed. The vulcanization of natural rubber by the benzothiazolesulfenamide class of accelerators is studied, where 2-(morpholinothio) benzothiazole (MBS) has been chosen as the representative accelerator. The reaction mechanisms that have been proposed for the different steps in vulcanization chemistry are critically evaluated with the objective of developing a holistic description of the governing chemistry, where the mechanisms are consistent for all reaction steps in the vulcanization process. A fundamental kinetic model has been developed for accelerated sulfur vulcanization, using population balance methods that explicitly acknowledge the polysulfidic nature of the crosslinks and various reactive intermediates. The kinetic model can accurately describe the complete cure response including the scorch delay, curing and the reversion for a wide range of compositions, using a single set of rate constants. In addition, the concentration profiles of all the reaction intermediates as a function of polysulfidic lengths are predicted. This detailed information obtained from the population balance model is used to critically examine various mechanisms that have been proposed to describe accelerated sulfur vulcanization. The population balance model provides a quantitative framework for explicitly incorporating mechanistically reasonable chemistry of the vulcanization process.
Antioxidant Selection for Peroxide Cure Elastomer Applications
Authors: Ferradino Anthony G. 
Published: February 2011

Abstract
For applications demanding the best high temperature aging performance with lowest compression set, polymers are crosslinked with peroxides. The carbon-carbon bonds that are formed are more thermally stable than crosslinks containing sulfur atoms generated by conventional vulcanization by sulfur- and sulfur based cure systems.
However, peroxide crosslinking requires special attention to the selection of compounding ingredients. Materials such as plasticizers, oils, and acidic materials such as silicas and air-floated clays detract from crosslinking efficiency by competing with the polymer for the free radicals produced by peroxides. Antioxidants, as a class, are free-radical scavengers and inhibit peroxide crosslinking.
This paper discusses selecting the best antioxidant systems for peroxide cured elastomers by comparing various classes of antidegradants: peroxy and alkoxy radical traps (amines and hindered phenols), hydroperoxide decomposers, and synergists. Among the most effective include: 1) a quinoline polymerized 1,2-dihydro-2,2,4-trimethylquinoline 2) an amine, p-dicumyl-diphenylamine, 3) a hindered phenol, tetrakis (metylene (3,5-di-t-butyl-4-hydroxy-hydrocinnamate)) methane, and 4) a dithiocarbamate, nickel dimethyl-dithiocarbamate. For optimum performance, these are used in combination with the synergist, zinc-2-mercaptotoluimidazole.
Also presented is an antioxidant system optimization study using a statistically designed experiment.
Adhesion of Rubber to Magnesium Alloys in the Presence of Nickel Branched Alkyl Carboxylates
Authors: Mori K. , Shi X. , Hirahara H. , Oishi Y. 
Published: February 2011

Abstract
The authors investigated the adhesion of rubber compounds containing nickel blanched alkyl carboxylate to surface treated magnesium alloys during curing. Ni i-octylate and Ni i-stearate were used as nickel branched alkyl carboxylate. Rubbers used in the study did not adhere at all to magnesium alloys, such as AZ91, AZ31, AZ 21, and M1 washed with acetone; not even in the presence of Ni i-octylate. Among numerous treating solutions, only sodium hydroxide aqueous solution was effective for adhesion of rubber to magnesium alloys. Adhesion of rubber to magnesium alloy AZ31 treated in 0.5M- sodium hydroxide aqueous solution for 10 min at 80 °C yielded high peel strength and a 100% rubber coverage. Peel strength and a 100% rubber coverage varied with the concentration of additives, such as curing accelerators, sulfur, zinc oxide and Ni-type adhesive accelerators. Ni branched alkyl carboxylates such as Ni i-octylate and Ni i-stearate were effective for accelerating the adhesion of rubber to magnesium alloys treated in sodium hydroxide aqueous solutions during curing. The authors postulate that Ni branched alkyl carboxylate acts to yield interface bonds between magnesium alloys and rubber or Ni-S-rubber linkage.
Distribution of Elastomers and Silica in Polymer Blends Characterized by Raman Microimaging Technique
Authors: Zerda T. W. , Song G. , Waddell W. H. 
Published: February 2011

Abstract
Raman microimaging technique was used to study the distribution of silica filler and elastomer domains in binary and ternary polymer blends containing cis1–4-polybutadiene BR; brominated poly(isobutylenecoparamethylstyrene) BIMS; Natural Rubber, NR; and/or Styrene-Butadiene Rubber, SBR. Contour maps depicting distribution of the elastomer phases and silica within each phase were obtained for 1 μm thick sections of blends having different compositions. All polymers were uniformly distributed throughout the blends. However, on a micrometer scale local fluctuations were clearly observed using Raman microimaging. The BR component is not as compatible with BIMS as are the other polymers based upon the presence of some single-phase BR domains exceeding 5 μm. Addition of the third polymer, either SBR or NR, to the blend improves the BR compatibility with BIMS since the BR domains are not as large. At low concentrations in a ternary blend, the NR phase appears concentrated near the BR domains, but in samples with higher NR concentrations, the natural rubber forms it own network and may also be found near the BIMS domains. The SBR phase was found to be near or within the BR domains. Silica was dispersed throughout the polymers in each blend, but tended to aggregate near the boundaries of the BIMS domains. Sometimes the silica was present within the BIMS domains, but did not locate within a BR domain.
Application of Scanning Transmission X-Ray Microscopy to the Rubber Industry
Authors: Winesett D. A. , Ade H. , Smith A. P. , Urquhart S. G. , Dias A. J. , Stevens P. 
Published: February 2011

Abstract
Materials of commercial significance in the rubber industry are usually multi-component systems composed of several elastomers and various fillers. Elucidating the complex morphology that can arise from blending and understanding how this affects the various properties are essential. A technique advantageous to the study of multi-component elastomeric systems is Scanning Transmission X-ray Microscopy (STXM). STXM utilizes the chemical sensitivity of Near Edge X-ray Absorption Fine Structure (NEXAFS) and combines with relatively high spatial resolution and low beam damage to allow the successful characterization of multi-component materials that may be difficult or impossible with other techniques. An overview of the technique and example applications for the rubber industry is presented.
On the Chemistry of Tetrabenzyl Thiuram Disulfide and Tetramethyl Thiuram Disulfide with Bis (Triethoxysilylpropyl) Tetrasulfide in Silica Compounds
Authors: Datta R. N. , Talma A. G. , Datta S. , Nieuwenhuis P. G. J. , Nijenhuis W. J. , Maslow W. 
Published: February 2011

Abstract
The use of thiurams such as Tetramethyl thiuram disulfide (TMTD) or Tetrabenzyl thiuram disulfide (TBzTD) has been explored to achieve higher cure efficiency. The studies suggest that a clear difference exists between the effect of TMTD versus TBzTD. TMTD reacts with Bis (triethoxysilylpropyl) tetrasulfide (TESPT) and this reaction can take place even at room temperature. On the other hand, the reaction of TBzTD with TESPT is slow and takes place only at higher temperature. High Performance Liquid Chromatography (HPLC) with mass (MS) detection, Nuclear Magnetic Resonance Spectroscopy (NMR) and other analytical tools have been used to understand the differences between the reaction of TMTD and TESPT versus TBzTD and TESPT. The reaction products originating from these reactions are also identified. These studies indicate that unlike TMTD, TBzTD improves the cure efficiency allowing faster cure without significant effect on processing characteristics as well as dynamic properties. The loading of TESPT is reduced in a typical Green tire compound and the negative effect on viscosity is repaired by addition of anhydrides, such as succinic anhydride, maleic anhydride, etc.
A Simple Approach to Characterize Finite Compressibility of Elastomers
Authors: Gurvich Mark R. , Fleischman Thomas S. 
Published: February 2011

Abstract
A hybrid experimental-numerical approach is proposed for accurate dimensionless characterization of rubber finite compressibility. Rubber specimens in the form of bonded rubber disks are considered as elastomeric structures with unknown material properties. These properties are calculated by matching results of FEA with experimental measurements of radial deformations of the axially-loaded disks. The approach may be used for reliable characterization of Poisson's ratio, bulk modulus, or other characteristics of interest. Implementation of the approach is considered for two representative elastomeric compounds with different levels of carbon black. Good experimental verification of the approach is shown at different levels of loading. Moreover, the same parameters of finite compressibility are independently obtained using both compressive and tensile loads. Higher compressibility is observed for a compound with larger content of carbon black as expected.
Devulcanization of Sulfur-Cured Isoprene Rubber in Supercritical Carbon Dioxide
Authors: Kojima M. , Ogawa K. , Mizoshima H. , Tosaka M. , Kohjiya S. , Ikeda Y. 
Published: February 2011

Abstract
A new devulcanization process that utilizes supercritical CO2 (scCO2) along with devulcanizing reagents was studied. Unfilled polyisoprene rubber samples (vulcanizates) with different crosslink distributions were prepared by controlling the cure time and the curatives. Each of the vulcanizates was subjected to the Soxhlet extraction using azeotropic acetone/chloroform to remove residual curatives. The devulcanization was performed at various temperatures (140–200 °C) in the presence of scCO2 for 60 min. The product was fractionated into sol and gel components, and molecular weight of the sol component and the crosslink density of the gel component were determined. Thiol-amine reagent was found to be effective among several devulcanizing reagents; the molecular weight of the resulted sol component was about tens of thousands and the crosslink density of gel component decreased substantially from the initial ones. Yield of the sol component increased with the increase in the CO2 pressure. In the supercritical fluid state of CO2, the vulcanizate was more efficiently devulcanized than in an ordinary gaseous state of CO2. The sol fraction depended considerably on the crosslink distribution in the vulcanizate. These results suggest that the devulcanizing reagents penetrate and diffuse into the vulcanizate in the presence of scCO2.
Influence of the Blend Viscosity and Interface Energies on the Preferential Location of CB and Conductivity of BR/EPDM Blends
Authors: Ibarra-Gómez Rigoberto , Márquez Alfredo , Ramos-de Valle Luis F. , Rodríguez-Fernández Oliverio S. 
Published: February 2011

Abstract
In the present work, the effect of distribution of Carbon Black (CB) and rubber viscosity over the conductivity of rubber blend composites was studied. Preferential location of CB predicted by surface tension measurements and calculation of interfacial energy (wetting coefficient) was corroborated by dynamic analysis (DMA) as well as bound rubber experiments. In this respect, the employment of the DMA technique to infer preferential distribution of CB, through the following of changes in the loss tangent (Tan δ), were proposed and successfully assessed in this study. A double percolation effect was evidenced by the appearance of a maximum in conductivity at relatively low EPDM content and CB concentration; however, when blend viscosity increases due to the addition of EPDM (the most viscous rubber), the double percolation effect is suppressed and the conductivity falls due to the prevailing dispersion effect of CB particles. According to these results, the blend viscosity was found to play a major role in the final conductivity of the studied composites.
Characterizing Gum Elastomers by Fourier Transform Rheometry
Authors: Leblanc Jean L. , de la Chapelle Christophe 
Published: February 2011

Abstract
Fourier transform (FT) rheometry is an emerging new technique that allows the linear and non-linear viscoelastic behavior of polymer materials to be accurately investigated. Basically samples are submitted to torsional harmonic strain at fixed frequency and temperature in order to capture strain and torque signals. A commercial instrument, i.e. the Rubber Process Analyzer RPA 2000® (Alpha Technologies), was suitably modified, essentially in using a fast electronic analogic-digital conversion card to record and treat torque and strain signals using purposely written software. Details of such modifications were previously published and the work presented is a sequel of this development.
The quality of the applied strain is first precisely documented through FT and found excellent, particularly in the high strain range. Three gum EPDM with different macromolecular characteristics (MWD and long chain branching) were analyzed either using standard dynamic testing, i.e. essentially in the linear viscoelastic range, or using the Fourier transform rheometry approach, by considering data gathered in the far non-linear viscoelastic range. Data obtained are considered with respect to know features of the samples.
A series of SBR 1500 samples, collected from various manufacturers, were first analyzed using standard methods; as expected very small differences were seen. Then FT was used to consider torque signals at very high strain (up to 400% at 1 Hz). Using a simple 4-parameter model to treat the variation upon increasing strain of the relative third harmonic component of the torque signal, differences are clearly detected that are discussed with respect to available polymer manufacturing information.
Tailoring Polymer Molecular Structure in the EPDM Slurry Process
Authors: Bhattacharjee Susmita , Bender Harald , Padliya Dilip 
Published: February 2011

Abstract
EPDM is produced by different polymerization processes. Therefore, careful engineering of polymer micro- and macro- structures is necessary to achieve desired performance characteristics. This review highlights the process capability of the EPDM slurry technology to tailor and control the molecular structural design. The catalyst and the polymerization technology produce EPDMs with a wide spectrum of chemical composition and Mooney viscosity. The relatively narrow molecular weight distribution of the polymers has been designed to offer the best combination of processing and physical properties. A unique technology for incorporation of long chain branching in the polymer has been developed. This highly selective catalyst technology controls the degree of branching and molecular weight distribution without any side reaction, while offering the flexibility to vary polymer composition and molecular weight. The EPDMs made with the modified molecular structure have a good balance of processing and performance characteristics.
Effect of Temperature and Pressure on Segmental Relaxation in Polymethylphenylsiloxane
Authors: Pawlus S. , Rzoska S. J. , Ziolo J. , Paluch M. , Roland C. M. 
Published: February 2011

Abstract
Segmental relaxation in a series of polymethylphenylsiloxanes (PMPS) was studied using dielectric spectroscopy. The measurements covered a temperature range of more than 40 deg at pressures from ambient to 115 MPa. The results confirmed that the shape of the loss peak is independent of temperature, pressure and molecular weight. Consequently, the Tg -scaled dependence of the relaxation times was also independent of molecular weight. The pressure dependence of the relaxation times was characterized by means of the activation volume. This quantity changes markedly with pressure at a given temperature. However, the activation volume at the respective glass transition temperatures of the PMPS are essentially invariant to molecular weight. Finally, we measured the dependence of Tg on pressure, with the results well-described by the Andersson equation.
Effects of Accelerator Type and Curing Temperature on Crosslink Distributions and Tensile Properties of Natural-Acrylic Rubber Blends
Authors: Clythong N. , Wootthikanokkhan J. 
Published: February 2011

Abstract
Effects of curing temperature and accelerator type on tensile properties of natural-acrylic rubber blends (NR:ACM) were investigated. Three different types of accelerators namely, MBT, ZDEC and DPG, were separately compounded with the rubber blends (50/50, % w/w) along with stearic acid, ZnO, sodium stearate, and sulfur (S) on a two-roll mill. The compounded blends were vulcanized to their optimum cure time in a hydraulic press at 150 and 170 °C. Morphology and tensile properties of the rubber blends were determined by using a scanning electron microscope and a universal testing machine, respectively. Crosslinking characteristics of both NR and ACM phases in the rubber blends were investigated by using a swollen state 1H-NMR and a differential swelling technique. From the tensile test, it was found that strength and strain of the blend vulcanized with the S/ZDEC curing system were remarkably lower than those of the blends vulcanized with the S/MBT and S/DPG systems. The superior tensile properties of the two latter blending systems were accompanied by greater chain mobility of both of the NR and ACM molecules, along with a lower volume fraction of rubber in swollen gel (Vr) of the both NR and ACM phases. These changes were discussed in the light of various possibilities including curative distribution, which were affected by the accelerator type. In term of the effects of curing temperature, it was found that Vr and tensile properties of the blends did not significantly change with the temperature.
Determination of Chemical Components that Cause Mal-Odor from Natural Rubber
Authors: Hoven Vipavee P. , Rattanakaran Kesinee , Tanaka Yasuyuki 
Published: February 2011

Abstract
Odorous components emitted from different forms of solid natural rubber (NR) were analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) associated with head space sampling technique. The most odorous components from most samples were identified as low molecular weight volatile fatty acids (C2-C5). Other volatile organic contents verified based on characteristic ions of mass spectra included carbonyl compounds, low molecular weight compounds containing nitrogen or sulfur and aromatic compounds. The total content and composition of volatile organic compounds were directly correlated to the rubber quality and drying process. Low-grade NR samples, i.e. STR 20 from cup lumps with intense smell, had high quantity of volatile organic contents especially low molecular weight volatile fatty acids. On the other hand, high-quality rubber, i.e. deproteinized NR and STR 5L from which no smell was detected, contained only minute quantities of volatile organic contents. Aromatic components were regarded as other major odorous contents found in ribbed smoked sheet (RSS) samples. The results suggested that the odorous components were the by-products of non-rubber components which had undergone microbial breakdown during storage or thermal degradation during processing.