bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Processing of Filler-Reinforced Rubber
Authors: Dizon E. S. , Papazian L. A. 
Published: February 2011

Abstract
Further insight into the mixing process has allowed a definition of the intermediate objectives of processing, which relate to the different transformations that occur as mixing energy is added to a rubber formulation. These convert the ingredients into a coherent mass with specific flow characteristics and determine the efficiency of the next unit, therefore contributing to overall productivity. The total energy added to the batch is derived from a combination of Banbury, mill, and extruder. These processing units vary in the efficiency with which they achieve the required material transformations. Proper allocation of mixing energy to the most effective equipment, with a knowledge of the total energy required to achieve the desired quality, allows a rational optimization of productivity and product quality. Operating profiles for each unit have been constructed in order to aid in optimizing the process. Using a fixed total energy input, these profiles were used to estimate the productivity of each processing unit. The study shows that in a semicontinuous operation with laboratory-size Banbury, mill, and extruder, the extruder is the primary determinant of overall productivity. The study also shows that maximizing productivity in a single unit will not necessarily lead to the highest productivity along the equipment train. Material properties affect overall productivity in several ways. In this work, carbon black surface area determined the total energy required to attain the desired quality level, the flow rate in the extruder, and the energy required to attain the maximum flow rate. Future studies should focus on the derivation of operating equations for specific equipment and materials. These equations should quantify the interrelationships between the different engineering parameters (such as screw or rotor speeds and Banbury ram pressure), the processing parameters (such as mixing time, fill factor, and temperature), and material variables (such as Mooney viscosity, carbon black morphology, and black and oil loading).
Fundamental Observation on Deformation and Failure Characteristics of SBR 1500
Authors: Nakajima N. , Collins E. A. 
Published: February 2011

Abstract
The processing of raw elastomers involves viscoelastic properties at both small and large deformations. It also involves ultimate properties, because the deformation under processing conditions often exceeds the failure limit. The present work describes these properties in the processing ranges of temperature and deformation rate. Therefore, the results may be used for interpreting processability. Also, relative differences in molecular weight, its distribution, long-chain branching, and gels may be detected by comparing the above data for different samples. The results summarized in master curves and a failure envelope indicate that the essential information is obtainable with limited experiments, for example, with the Rheovibron and the variable-speed Mooney rheometer.
Application of Headspace Gas Chromatography to Analysis of Residual Volatiles in Synthetic Rubbers
Authors: Pausch J. B. , Sockis I. 
Published: February 2011

Abstract
The environmental concern for chemicals covers a broad spectrum in the world of today. There are traces of chemical compounds in the air, water, and soil that must be measured and identified, especially around a chemical or rubber plant. Likewise, the total composition of our industrial rubber products has become a major issue. We want to protect the rubber manufacturing worker, the rubber processing and fabricating people, and finally the consumer from exposure to possible toxic substances, undesirable odors, or any other type of irritant that may result from residual volatiles or decomposition products of our rubber products. For many years the conventional analytical technique for measuring residual monomers, solvents, and other small molecule impurities in rubber has been gas chromatography (GC). The sample was dissolved in a suitable solvent and chromatographed. However, the analytical requirements in the last couple years have dictated lower levels of detection than are possible with the solution method using flame ionization detection. Different approaches to this analytical problem have been widely discussed and will not be reviewed here. Briefly, they include the use of specific GC detectors, such as the electron capture detector for halogenated and other electron deficient compounds; specific detectors for nitrogen, sulfur, and phosphorus compounds; and the photoionization detector, which has become commercial within the last year. A recent paper described a modified solution approach combined with headspace GC. Each of these methods is suitable in certain analyses but does not represent a good general technique for hydrocarbon analysis in solid rubber materials. This paper describes various aspects of headspace gas chromatography as a general method for direct measurement on solid rubber samples for trace levels of residual volatiles. In addition, several other important advantages result from the elimination of the solvent.
Staining Natural Rubber with Silver Nitrate for Electron Microscopy
Authors: Smith R. W. , Folt V. L. 
Published: February 2011

Abstract
Hevea brasiliensis or natural rubber (NR) has been used for over 500 years. Until World War II, it was the basic raw material of the rubber industry. Since that time, the use of synthetic polymers has steadily increased, but the importance of NR has not diminished. In fact, the future for the natural product is very promising since it is the one polymer that is obtainable without depleting fossil fuel raw materials. Natural rubber latex has been extensively studied by a variety of methods, especially the microscope. All of the early work with NR latex was conducted, of course, with the optical microscope. In the late 1940's the electron microscope began to be used, but at that time synthetic rubbers began to demand attention, and work on NR latex diminished. Perhaps investigators felt they knew all there was to know about the microscopical characteristics of this material. Indeed, some very fine work had been done and keen observations made with optical microscopes that could not even resolve all of the particles in a latex material. This paper deals with the electron microscopy of natural rubber latexes with particular attention to the proteinaceous layer on the particle and the fate of particles during varying stages of mastication. The critical technique used was to stain the proteinaceous layer of the latex particle with silver nitrate.
Isothermal and Nonisothermal Creep of Lightly Crosslinked cis-1,4-Polybutadiene
Authors: Caruthers J. M. , Cohen R. E. 
Published: February 2011

Abstract
A nonisothermal creep experiment has been analyzed to ascertain its suitability for determining the temperature dependence of low-activation-energy viscoelastic processes in elastomers far above Tg. The nonisothermal method was employed to determine the activation energy for creep near 35°C in a lightly crosslinkedcis-1,4-polybutadiene elastomer at small strains within the linear viscoelastic region and at various large deformations up to rupture. The observed activation energy was essentially independent of the level of strain, and the value of ΔHa (∼ 11 kcal/mol) determined via the nonisothermal creep method was in good agreement with the result (∼12 kcal/mol) obtained via time-temperature superposition of isothermal linear viscoelastic creep data. The nonisothermal data allowed for an estimate of the volume of the “flow unit” associated with the controlling viscoelastic creep mechanism, attributed here to slippage of entanglements within lightly crosslinked network.
Physical and Chemical Stress Relaxation of Elastomers
Authors: Curro J. G. , Salazar E. A. 
Published: February 2011

Abstract
In this paper we have developed a method whereby physical and chemical relaxation processes can be distinguished, using stress relaxation experiments as a function of temperature. We assumed that there exists some temperature range above the glass transition temperature over which the chemical effects can be neglected for the time scale of the experiments. The data in this low temperature range were then used to determine the WLF constants and other physical relaxation parameters. The physical component of the stress relaxation could then be subtracted from high temperature experiments in order to extract chemical kinetic information. Based on certain reasonable assumptions, an equation was developed for the relaxation modulus of a chemically reacting system. This equation could be used to determine the time dependence of the crosslink density, or conversely could be used to predict the long-term relaxation modulus from an assumed kinetic mechanism. These calculations were demonstrated for ethylene-propylene and butyl elastomers.
Isochronous Stress-Strain Relationship in Compressive Stress Relaxation of Vulcanizates
Authors: Stenberg B. , Jansson J. F. 
Published: February 2011

Abstract
The mechanical and other properties of natural and synthetic rubbers can be regulated by the incorporation of fillers. The mechanical behavior of the resulting complicated heterogeneous systems is often difficult to describe theoretically. These vulcanizates have wide and useful applications under conditions of multiaxial stresses. In many cases, however, the stresses act mainly in compression, for instance, in gaskets, seals, suspension systems for vibration insulation, etc. Thus the stress relaxation properties in compression are of vital importance. In spite of this, very few studies have given attention to the stress-strain relations in compression, and the results reported in the literature concentrate mainly on the mechanical behavior of rubbers in tension. We now report a study of the isochronous stress-strain relation in compression for some rubbers at 295 K, based on stress relaxation measurements. A comparison is made between the behavior of samples which have been greased and of samples which have been glued to the deformation plates.
An Elastomeric Micrometering System for the Controlled Administration of Drugs
Authors: Wright J. C. , Buckles R. G. , Dunn J. T. , Leeper H. M. , Yum S. I. 
Published: February 2011

Abstract
When drugs are infused, it is often necessary to minimize the volume of fluid delivered. Fluid delivery rates of 1 cm3/h or less are frequently desirable; however, the accurate metering of fluids at such low flow rates to the human body has been difficult to accomplish. The metering devices most commonly used to control flow rate from a constant-pressure source have been micrometer valves, clamped tubes, capillaries, and porous plugs. Each of these devices has specific disadvantages : micrometer valves are expensive and bulky, clamped tubes are not stable for long-term infusion and present a hazard of greatly fluctuating flow rates, capillary tubes are subject to particle blockage and are not adjustable, and porous plugs suffer from lack of adjustability. Recently a valve made of extruded silicone rubber rod with axial holes was reported to yield stable flow rates; it was adjusted by placement in a plastic clamp. A new low-infusion-rate metering system has been developed to overcome the above deficiencies. This system consists of axially aligned polyurethane fibers contained within the lumen of a length of silicone rubber tubing. The fibers fill the lumen to the extent that they are subjected to a compressive hoop stress by the tubing. The assembly represents two elastomeric materials in states of strain, exerting equal and opposite stresses on each other. The elastomeric tubular assembly is contained in a rigid, adjustable, U-shaped enclosure that controls the deformation of the assembly. While other elastomeric materials would be suitable for the elastomeric valving system, we report here on our experience with polyurethane fibers and silicone rubber tubing. These materials were selected for their expected compatibility with most aqueous drugs and their availability.
Role of the Elasticity of Rubber in the Controlled Administration of Drugs
Authors: Leeper H. M. , Buckles R. G. , Guittard G. V. , Lorberbaum M. A. , Sevilla E. R. , Yum S. I. 
Published: February 2011

Abstract
The energy stored in an extended elastomeric reservoir can be usefully employed in the controlled delivery of drug solutions at constant rates of flow through a fixed resistance. The absolute level and constancy of pressure presented to the upstream end of the flow restrictor can be related, respectively, to the geometry and composition of the elastomeric reservoir. (The reservoir is to contain, in its distended form, the volume of drug to be delivered to the human venous system.) It has been established that the defining criteria for minimizing static pressure loss in the reservoir and for maintaining constancy of pressure through most of the delivery interval are stress decay and hysteresis, as measured in uniaxial stress-strain testing. The elastomeric composition most successfully meeting these requirements has been found to be non-reinforced isoprene rubber, crosslinked with a peroxide.
Preparation of Radioactively Tagged Ethylene-Propylene Copolymers. Calculation of the Block-Length Distribution from the Kinetic Data
Authors: Exner J. , Seeger M. , Cantow H-J. 
Published: February 2011

Abstract
A series of statistical copolymers is available for our studies of the mechanisms of thermal decomposition of ethylene-propylene copolymers and their sequence distribution. However, the analytical evidence can be improved appreciably by the use of radioactively tagged copolymers and radio-gas chromatography. A loss of information occurs when untagged polymers undergo α-scission. Even if the chain breaks directly at the tertiary carbon atom, the scission product stabilizes itself by forming a terminal double bond. Accordingly, the position of double bonds gives no information about the location of methyl side groups in copolymers. However, if the α-methyl groups are radioactively tagged, as shown in the formula above, radioactive counting of linear fragments can demonstrate their original methyl side groups. Thus, α-scissions of copolymers can be directly determined.
Visualization of Flow during the Processing of Rubber in an Internal Mixer
Authors: Freakley P. K. , Idris W. Y. Wan 
Published: February 2011

Abstract
The flow visualization method of studying internal mixing has been shown to be a powerful tool for determination of the critical factors influencing flow and mixing efficiency. Correlation of visualizations with results obtained for “practical” rubber mixing confirms the validity of the method for the prediction of flow in conventional mixing operations. Fill factor is identified as one of the key variables influencing mixing uniformity. At this stage it is not possible to make general recommendations since only limited studies were carried out. However, from the dependence of mix uniformity on fill factor derived from a B Banbury having two-wing rotors, fill factors of 0.7–0.8 are shown to give the best results. This range of fill factors provides an adequate and continual filling of the region in front of the rotor tip and ensures that the high stresses required for the fracture of particle material aggregates are generated. It also permits the formation of voids behind the rotor tips. Such voids appear to be essential for the disordering of streamline flow patterns and for promoting effective axial tranfer of material.
New Generation Polyacrylate Elastomers
Authors: Demarco R. D. 
Published: February 2011

Abstract
Polyacrylate elastomers have come a long way since the first large-volume commercial product was introduced in 1948. Rapid cure rates with relatively mild cure systems are now possible. Low temperature limits have been extended from −15°C to the −30 to −40°C range, while maintaining good oil resistance. The need to post cure has been removed in some processes and minimized in others. Future trends in ACM research are aimed at improving strength (especially abrasion), complete elimination of post cures, and improved fuel (especially gasoline) resistance.
The Filler—Elastomer Chemical Link and the Reinforcement of Rubber
Authors: Le Bras J. , Papirer E. 
Published: February 2011

Abstract
The results confirm the rationale which guided the experiments. The mechanical properties of the vulcanizate prepared without any milling and containing a carbon black chemically grafted to part of the elastomer are definitely superior to those of the blank, prepared under the same conditions with an ungrafted black. This indeed proves that merely creation of a chemical bond between the carbon black and the rubber brings about reinforcement and that, therefore, the reinforcement mechanism cannot be solely accounted for by physical interactions. Of course, optimum reinforcement as would be observed by classical mixing is not attained, since in this case complementary effects intervene. We believe that, for the first time, we have given absolute proof that the establishment of a chemical link between the carbon black and the elastomer induces reinforcement. New experiments are in progress with SBR; they should accentuate the differences in mechanical properties taking into account the very low values for nonreinforced vulcanizates.
Creep Resistant Elastomer Formulations
Authors: Meier J. F. , Rudd G. E. , Weir D. F. 
Published: February 2011

Abstract
Over 150 elastomer formulations of NR, DPNR, CR, IIR, AU, EU, EO, ECO, SBR, EPM, EPDM and a silicone rubber have been evaluated to identify the most creep resistant materials. Selected data are presented. Three of the best formulations (DPNR compound 15, CR compound 27 and EPDM compound 49) were found to give excellent creep performance extrapolating to less than 28% relative creep for a 15 year service life. As a result of a requirement for 15 year resistance to 25 pphm O3 concentration, EPDM formulation 49 was selected, and pads were molded and compression tested. Because of the O3 resistance of EPDM, there should not be a significant increase in creep rate.
Mechanics of Fracture in Two-Ply Laminates
Authors: Breidenbach R. F. , Lake G. J. 
Published: February 2011

Abstract
This paper describes a study of fracture in two-ply rubber—cord composites subjected to repeated tensile deformations. Under the conditions used, failure occurs predominantly because of the growth of cracks between the plies. A fracture mechanics approach enables the rate of crack growth to be predicted in terms of the elastic properties and dimensions of the laminate, the magnitude of the deformations and the basic crack growth characteristics of the ply rubber. The theory indicates the growth rate to be determined by the strain energy released from the central region of the laminate and to be independent of crack length once this exceeds a small value. The latter feature has been verified experimentally and the magnitudes of the observed crack growth rates are in reasonable agreement with those predicted for various deformation cycles.
Method of Obtaining Viscosity Curves with Mooney Rheometer
Authors: Nakajima N. , Harrell E. R. 
Published: February 2011

Abstract
A mathematical expression is derived for calculating shear stresses from torque values observed with the Mooney rheometer. Examination of this expression indicates that some improvement is possible in the rotor design. The numerical values of the conversion factor are given for both small and large rotors. The application of these factors to the observed data give viscosities in agreement with those obtained with other instruments. Low shear viscosities down to 10−3 and in some cases 10−4s−1 are obtained with the Mooney rheometer operated at 0.05 rpm for several minutes.
Effect of Vulcanization Temperature and Different Fillers on the Properties of Efficiently Vulcanized Natural Rubber
Authors: Mukhopadyay R. , De S. K. 
Published: February 2011

Abstract
The present work deals with effect of vulcanization temperature on the polymer-filler interaction parameter, vulcanizate structure, and the technical properties of efficiently vulcanized natural rubber stocks in the presence of different fillers. We have used carbon blacks of four different particle sizes (ISAF, HAF, SRF, FT), reinforcing silica, and whiting. In the case of black fillers, as the particle size increases, reversion resistance increases. For all fillers, an increase of curing temperature from 150 to 180°C caused a reduction in strength, modulus, hardness, resilience; and an increase in elongation at break, compression set, and heat build-up. However, the flexing properties and abrasion loss showed improvement at higher curing temperature. Kraus' plots indicate that increase of curing temperature caused reduction in polymer-filler attachment. At both curing temperatures, the activity of fillers follow the order, ISAF &gt; HAF &gt; SRF &gt; FT. Silica showed erratic behavior in that Kraus plots indicate nonreinforcement by the filler. Whiting also behaved abnormally with respect to Kraus plots; at lower filler loading, the system is nonadherent, becoming weakly adherent at higher concentrations. The abnormal behavior of silica-filled compounds has been explained on the basis of a reaction on the silica surface between silanol groups and zinc stearate. Westlinning and Wolff's αF values were found to be independent of curing temperature and characteristic of fillers only (the larger the particle size, the lower is the αF value). The increase in apparent crosslinking density in the case of reinforcing fillers is due to increased υr arising out of increased polymer-filler interaction. Therefore, the sulfur inefficiency parameters (E values) and zinc sulfide efficiency parameters (F values) become less significant in filled vulcanizates.
The Entanglement Plateau in the Dynamic Modulus of Rubbery Styrene—Diene Block Copolymers. Significance to Pressure-Sensitive Adhesive Formulations
Authors: Kraus G. , Rollmann K. W. 
Published: February 2011

Abstract
Styrene-diene (butadiene or isoprene) block copolymers of the SDS or (SD−)x type exhibit a plateau in the dynamic storage modulus located between the glass transitions of the polydiene and polystyrene domains. When the polydiene is the continuous phase, the height of this plateau can be estimated with good success from the entanglement spacing molecular weight of the polydiene and the filler effect of the polystyrene domains. The effect of introduction of a center block-compatible diluent can also be calculated, although the simple procedure used here tends to underestimate the plasticizer effect, particularly at high diluent concentration. Nevertheless, the calculation furnishes a useful criterion of compatibility of the polydiene center blocks and low molecular weight resins used commonly as tackifiers in pressure-sensitive adhesives. Center block compatibility is essential for the development of tack in these compositions.
Ultrasonic Measurements with Rubber Compounds during Extrusion
Authors: Caspary R. , Kretschmer P. 
Published: February 2011

Abstract
The dependence of the Index of Elasticity, E, the reciprocal value of sound velocity, on temperature and pressure is related to specific volume and compressibility of rubbers. The sensitivity of E towards changes of temperature and pressure was calculated, indicating a new versatile possibility for the control of rubber extruders. To confirm this, extruder experiments were carried out with an SHR compound, of which a working diagram was established showing the complete behavior of E=f(p,T). The effect of compound composition, especially of plasticizer and carbon black content, was examined. Viscosity in the extruder primarily determines changes in E. The method was shown to be applicable up to a die diameter of at least 200 mm. The method may also be applied to follow degradation of rubber compounds during mastication.