bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman and ESR Spectroscopic Studies of Accelerator Systems. I. Raman Spectra of Thiuram Sulfides and Related Compounds
Authors: Coleman M. M. , Shelton J. R. , Koenig J. L. 
Published: February 2011

Abstract
The Raman spectra of similar thiuram type materials are intense and very distinctive. Raman spectroscopy should prove to be an excellent analytical tool for studying complex mixture of thiuram type materials resulting from the chemical reactions that occur at vulcanizing temperatures.
Raman and ESR Spectroscopic Studies of Accelerator Systems. II. Thermal Degradation Vulcanizing Systems and Its Significance to Vulcanization Mechanisms
Authors: Coleman M. M. , Shelton J. R. , Koenig J. L. 
Published: February 2011

Abstract
Raman and ESR spectroscopy has been used to study the thermal decomposition of accelerator systems based on derivatives of dimethyldithiocarbamic acid. The combination of these two spectroscopic techniques has proved to be a very powerful method for detecting intermediate compounds that are important for the elucidation of the mechanism of accelerated sulfur vulcanization.
Influence of Curing Agents on Rubber-to-Textile and Rubber-to-Steel Cord Adhesion
Authors: Albrecht K.-D. 
Published: February 2011

Abstract
The results presented in this paper show that the dosage of sulfur greatly influences rubber-to-textile and rubber-to-steel cord adhesion. As far as rubber-to-textile adhesion is concerned, the pull-out strength is reduced when the sulfur level falls below 2 phr, the extent of the reduction depending on the type of fiber and the bonding process. With steel cord the lower limit for sulfur is as high as 3 phr. This is discouraging because it shows that the use of efficient and semi-efficient vulcanization in the manufacture of goods reinforced with fabrics or steel cord is, to say the least, highly problematical. On the other hand, it is often desirable to reduce the proportion of sulfur in order, for instance, to increase resistance to aging and reversion and to reduce compression set and heat build-up. The choice of accelerators also has an important influence on adhesion. A sufficiently long scorch time is required to allow complete wetting of the reinforcing material by the rubber compound. If curing starts before complete wetting of the textile or steel cord has occurred, adhesion cannot be built up. For example, unsatisfactory or no rubber-to-textile and rubber-to-steel cord adhesion is obtained, when ultra-accelerators are used. As the scorch time increases, adhesion improves. Best results are obtained with sulfenamides, but sulfenamides showing increasing scorch time give no improvement in rubber-to-textile bonding. However, DCBS gave much better results for rubber-to-steel cord adhesion than the other sulfenamides and thus appears particularly suitable. Although the results given by the other sulfenamides can be somewhat improved by the addition of a retarder, pull-out strength values do not reach those given by DCBS. Any decrease of scorch time of a compound deteriorates adhesion whether scorch time is reduced by compounding ingredients or by heat history imposed by processing. MBI, used as an antioxidant, which reduces scorch time drastically, causes complete loss of rubber-to-steel cord adhesion and also impairs rubber-to-textile adhesion. Most of the antioxidants, however, have a beneficial effect on mbber-to-steel cord adhesion. For zinc-plated steel cord antioxidants of the amine type give results inferior to those of the phenolic type. To obtain optimal rubber-to-textile and rubber-to-steel cord adhesion the compounder primarily has to consider the efficacy of the bonding agents but in addition he has to take into account the effects which may be exerted by compounding ingredients and processing conditions.
Characterization of New Technology Carbon Blacks
Authors: Medalia A. I. , Dannenberg E. M. , Heckman F. A. , Cotten G. R. 
Published: February 2011

Abstract
In this paper we have examined a limited number of conventional and new technology blacks, using the “t” method of nitrogen adsorption for comparison of surface area and dibutyl phthalate adsorption (DBPA) for comparison of structure. At a given “t” area the new technology blacks are of lower iodine number; conversely, at a given iodine number, the new technology blacks are of higher “t” area. This is not due to porosity, but rather to differences in carbon black-iodine surface interaction. The DBPA tests gives a fairly consistent measure of carbon black structure in rubber, for both types of blacks. An important difference between the two classes of black is in the higher tinting strength of new technology blacks, at a given “solid sphere” diameter (which depends primarily on the “t” area and to a lesser extent on the DBPA). We have introduced the use of a disk photosedimentometer for studying carbon black aggregate size distributions and have found that at a given “t” area, the distribution curves for the new technology blacks are shifted in the direction of smaller Stokes diameters. This can account, at least qualitatively, for their higher tinting strength. Electron microscopy supports the shift in Stokes diameters, at least qualitatively, and also indicates a more open aggregate morphology for the new technology blacks. The new technology blacks impart a higher level of reinforcement, at the same “t” area, as shown by tensile strength and roadwear. This is accompanied by a higher loss tangent or lower rebound. These properties may be due in part to a higher surface activity, as shown by a higher moisture adsorption and higher bound rubber, and partly to morphological differences, as shown by the smaller Stokes diameters and higher tinting strength. In summary, the higher bound rubber and higher tinting strength of the new technology blacks reflect differences in surface activity and aggregate size, which are responsible for the superior reinforcement shown by these blacks at a given “t” area.
Chemorheology of Irradiation-Cured Natural Rubber. I. Stress Relaxation Mechanisms for Various Curing Systems in Natural Rubber at High Temperature
Authors: Tamura S. , Murakami K. 
Published: February 2011

Abstract
1. There was no difference of stress relaxation, either in air or in nitrogen, between DCP cures (Sample 1) and irradiation cures (Sample 2). This suggests that these vulcanizates have the same physical and chemical structures. In air Samples 1 and 2 underwent random scission of only the main chain. 2. In the case of irradiation-TMTD cures (Samples 4 and 5), the stress decay was also based on oxidative scission of the main chain. The number of moles of main chain scission, qm(t), was independent of the ratio ρ (of Nc(0)) based on the carbon—carbon bonds to Nm(0) based on the mono- and disulfide links). However, qm(t) was larger than that of Sample 2. The oxidative scission of the main chain seemed to be accelerated by mono- and disulfide. It was found from comparison of Samples 4 and 5 that TMTD cures (Sample 3) underwent random scission on the main chain. The stress relaxation in nitrogen for Samples 3, 4, and 5 was due to thermal scission of the crosslink. 3. The stress relaxation, either in air or in nitrogen, of accelerated-sulfur-cures (Sample 6) and irradiation-sulfur cures (Samples 7 and 8) was expressed by the sum of two exponential terms. The stress relaxation in air of Samples 6, 7, and 8 could be explained by the interchange reaction of polysulfide links and the random scission on the main chain. The stress decay in nitrogen of these vulcanizates was based on both interchange of polysulfide links and thermal scission of crosslinks. The rate of the interchange reaction in air was very closely consistent with that in nitrogen. 4. The apparent activation energy of oxidative scission of the main chain was about 21 kcal/mol for Samples 2, 6, 7, and 8 and 27 kcal/mol for Samples 3, 4, and 5.
Entanglement Networks of 1,2-Polybutadiene Crosslinked in States of Strain. I. Crosslinking at 0°
Authors: Kramer O. , Carpenter R. L. , Ty V. , Ferry J. D. 
Published: February 2011

Abstract
Linear 1,2-polybutadiene is crosslinked at 0° (12° above Tg) by γ-irradiation while strained in simple extension, with extension ratios(λ0) from 1.2 to 2.0. After release, the sample retracts to a state of ease (λg) at room temperature. From (λ0), (λg), and Young's modulus in the state of ease Eg, the molar concentrations of network strands terminated by crosslinks (νx) and by trapped entanglements (νN) are calculated by composite network theories of Flory and others. With increasing irradiation time t, (νx) (corrected for free ends) is directly proportional to t and (νN) attains a constant value. With increasing λ0, νx is constant and νN diminishes somewhat. Extrapolated to λ0=1, νN is somewhat smaller (1.2×10−4 mol cm−3) than the concentration of entanglement strands estimated from viscoelastic measurements on uncrosslinked polymer in the plateau zone (νe=2.5×10−4). Young's modulus was also calculated indirectly from equilibrium swelling in n-heptane. The swelling is slightly anisotropic, being larger in the direction of extension.
Anisotropy in Molded Nitrile Rubber
Authors: Blow C. M. , Demirli H. B. , Southwart D. W. 
Published: February 2011

Abstract
Measurements of linear swelling in solvent of small test pieces provide a useful means of investigating anisotropy in vulcanized products and components whose small size precludes the use of conventional tests on dumbbells, etc. Anisotropy has been found to be present in molded components. The extent of this is related to the material flow in the mold before or during vulcanization. There also appears to be an effect of flow on crosslink density. In this preliminary investigation the contribution of each of the various factors, e.g., filler- filler structure, polymer gel, polymer-filler interaction, tendency to prevulcanize, has not been established.
Influence of Morphology and Particle Size of Powdered Rubber on Mill Processing
Authors: Bleyie P. L. 
Published: February 2011

Abstract
The powdered rubber method leads to a considerable shortening of mill mixing time and hence to a reduction of the specific energy required. While the transition from granular material to powder (from above 1 mm to below 1 mm particle size) has considerable effect both on mixing time and on specific energy, the effect of size reduction on specific energy for sizes below 1 mm is substantially smaller than expected from the surface area increase, probably, because a large part of the energy is used for carbon black dispersion. No effect of specific surface on specific energy and mixing time was found.
Recent Developments in the Use of Multi-Station Injection Molding Machines
Authors: Rienzner H. J. 
Published: February 2011

Abstract
The major marketing of injection molding machines for rubber started in the early 1960's when machine designs were developed that incorporated accurate control of stock feeding, injection pressure, and heat generation in the compound. The injection process is an excellent method for taking advantage of van't Hoff's rule, according to which the crosslinking reaction time is reduced approximately 50 per cent for each 10° C rise in stock temperature. Therefore, a high temperature as the stock comes into the mold cavity is desirable for rapid cures and increased productivity. Ideally there would be no heat transfer from the mold to the stock or from the stock to the mold.
Identification of Elastomers in Tire Sections by Total Thermal Analysis. I. Tread and Black Sidewall
Authors: Sircar A. K. , Lamond T. G. 
Published: February 2011

Abstract
Total thermal analysis provides a reasonably accurate method for the identification of the polymers in tire treads or black sidewalls. DSC curves in nitrogen distinguish SBR, BR, or blends from NR or IR. Tg then distinguishes between these polymers, although confusion may arise in the case of blends of SBR/BR with a high proportion of BR. DTG curves confirm the findings of DSC and Tg. Thus, by combining all the techniques mentioned, it should be possible to establish the nature of the polymers with reasonable accuracy. The method is rapid, requires no sample preparation or treatment of the sample, and operator attention is not necessary once the experiment is started. An estimate of the proportion of carbon black in the recipe may also be obtained from the TG curve or by weighing the sample after DSC experiment in nitrogen.
Preliminary Studies on New Anti-Reversion Agents for the Sulfur Vulcanization of Diene Rubbers
Authors: Blok E. J. , Kralevich M. L. , Varner J. E. 
Published: February 2011

Abstract
Recently, new materials have been introduced that minimize the loss of crosslink density and properties caused by over-cure and/or high temperature applications. One of these new anti-reversion agents, 1,3-bis(citraconimidomethyl)benzene, compensates for the loss in crosslink density through the formation of new crosslinks. This paper evaluates various multifunctional acrylates to determine if they will function like 1,3-bis(citraconimidomethyl)benzene and reduce reversion through the formation of new crosslinks. The experimental data suggests that some of these acrylates form new crosslinks during overcure conditions and therefore are very effective at maintaining the modulus and tan delta values upon overcure.
Strain Energy Function for Filled and Unfilled Rubberlike Material
Authors: Shariff M. H. B. M. 
Published: February 2011

Abstract
A general separable form of strain energy function with linear parameters is developed so that if a standard curve fitting method is used only a handful of linear equations need to be solved; the proposed function is formulated in such a way that only a few parameters are required to characterized the rubberlike materials. One of the parameters is the Young's modulus and this could facilitate a curve fitting algorithm if the value of the Young's modulus is known. A single constant, strain energy function is also proposed. The predicted curves agree well with numerous experimental data.
Some Aspects on the Crosslink Reaction of Natural Rubber with Dipentamethylene Thiuram Tetrasulfide
Authors: González L. , Rodríguez A. , del Campo A. , Marcos-Fernández A. 
Published: February 2011

Abstract
The mechanism of vulcanization of natural rubber with the sulfurating agent dipentamethylene thiuram was studied. On the transformation from crosslink precursor to crosslink, the route via disproportionation is preferred. In the presence or absence of zinc oxide and stearic acid as activators, the formation of the crosslink precursor follows similar processes, while the main difference is in the reaction induction times. In addition, the desulfuration reaction was favored by the presence of zinc oxide.
The Rheology and Processability of Tire Compounds
Authors: Schaal Stéphane , Coran Aubert Y. 
Published: February 2011

Abstract
The purpose of the work reported here was to define the parameters, which affect the rheology of tire compounds as well as their processability. Rheology was characterized over a wide range of shear rates. Processability was defined inversely as the roughness of the extrudate from the Monsanto Processability Tester (MPT) capillary rheometer. The roughness was measured by using image analysis of the extrudate surface contour. A good correlation was found between the extrudate roughness and the size of the Mooney peak (peak in apparent stress plotted against time for very small shear rates in a start-up flow experiment). The Mooney peak can be represented as a yield stress. The effects of storage time and temperature on the size of the Mooney peak (i.e., its increase as a function of storage time) was studied. The kinetics of degradation of processability was not found to follow an Arrhenius type of behavior. Finally, a physical descriptive model was proposed to represent filler—rubber structures.
The Effects of Certain Recipe Ingredients and Mixing Sequence on the Rheology and Processability of Silica- and Carbon Black-Filled Tire Compounds
Authors: Schaal Stéphane , Coran Aubert Y. , Mowdood Syed K. 
Published: February 2011

Abstract
The purpose of the work reported here was to study the effects of curing ingredients, filler such as silica and its moisture content, mixing sequence, and mixing scheme on the rheology and the loss of processability of the tire compounds at different storage temperatures. Rheology was characterized over a wide range of shear rates. For the retardation of the development of poor processability during storage of the compound (assumed to be caused, at least in part, by filler particle reagglomeration and formation of bound rubber), the most effective ingredients are diphenylguanidine (DPG), polyethylene glycol (PEG) and cyclohexylbenzothiazolesulfenamide (CBS), the latter being even more effective if the storage temperature is not too high (e.g., lower than 70 °C). Two orders of mixing were considered: (i) Y-mixing (the mixing of a silica-filled masterbatch with a carbon black-filled masterbatch), and (ii) all-in-one mixing (the mixing of the rubbers and fillers all at the same time, in a single batch). We also observed that the Mooney peak (peak stress in low-strain-rate start-up flow) and extrudate roughness (indication of poor processability) increase much more slowly with storage time for the Y-mixed compound than it does for the all-in-one-mixed compounds. Also, a low moisture level in the silica leads to poor processability as does high-temperature heat treatment during the mixing stage.
Stiffness of Rubber Bush Mountings Subjected to Radial Loading
Authors: Horton J. M. , Gover M. J. C. , Tupholme G. E. 
Published: February 2011

Abstract
Based on the classical theory of elasticity, an exact expression is derived for the radial stiffness of a cylindrical rubber bush mounting of finite length, in terms of modified Bessel functions. From this a convenient approximate representation is deduced. Some exact and approximate numerical results are compared with the experimental data which are available.
Raman Study of Kinetics of Graphitization of Carbon Blacks
Authors: Zerda T. Waldek , Gruber Tyler 
Published: February 2011

Abstract
Raman spectra of laser heated carbon blacks provide information on the dynamics of the graphitization process. Continuous wave and pulsed-laser heating is used. It is shown that two ordering mechanisms of distinctly different reaction rates are present during the heat treatment. The dominating mechanism, during the initial stages of graphitization, is characterized by a very fast rate. The rate during the later stages of the process, after the initial first couple of seconds, is orders of magnitude slower.
The Effect of Compressive Strain and Stress on Electrical Conductivity of Conductive Rubber Composites
Authors: Sau K. P. , Chaki T. K. , Khastgir D. 
Published: February 2011

Abstract
The electrical conductivity changes significantly when compressive strain and stress are applied on the conductive rubber composites derived from acrylonitrile—butadine rubber (NBR), ethylene—propylene—diene rubber (EPDM) and their 50:50 blend. The resistivity increases during application of compressive strain. However, the change of electrical resistivity depends on strain amplitude, amount of filler loading and type of polymer matrix. The change of resistivity with time for compressed samples has also been registered. But, during application of compressive stress (pressure), the resistivity is found to decrease for NBR and increase for EPDM and dual behavior is observed in blend. All the increase and decrease of resistivity with the application of stress and strain is explained on the basis of formation and destruction of a conductive network, which further depends on viscosity (stiffness) of the matrices. The observations are supported by the similar experiments with conductive silicone rubber composites.
A Model for Rubber Degradation under Ultrasonic Treatment: Part II. Rupture of Rubber Network and Comparison with Experiments
Authors: Yashin V. V. , Isayev A. I. 
Published: February 2011

Abstract
A simple theoretical model of network degradation around ultrasonically pulsating cavities is considered. The model is based on the concept of overstressed chains and provides a simple tool to estimate a number of chains which should be involved in mechanochemical degradation at a given amplitude of ultrasonic pulsation. High amplitude cavitation with no collapse-like effects is demonstrated to result in significant reduction of the rubber crosslink density. This model also predicts considerable effects of rubber degradation on elastic properties of rubber around a pulsating cavity including certain irreversible effects and residual deformations. The Dobson—Gordon theory of rubber network statistics is employed in order to interpret the experimental data on the dependence of gel fraction in devulcanized rubbers on crosslink density in the gel. Application of the approach to devulcanized styrene—butadiene rubber (SBR) and silicone rubber demonstrates that the assumption on spatial—temporal randomness of rubber degradation allows us to achieve a fairly good agreement between experimental and theoretical data.
Analysis of Rubber Particles Produced by the Solid State Shear Extrusion Pulverization Process
Authors: Bilgili E. , Arastoopour H. , Bernstein B. 
Published: February 2011

Abstract
Vulcanized natural rubber was pulverized using a single screw extruder in a non-cryogenic Solid State Shear Extrusion (SSSE) process where rubber granulates were subjected to high compressive and shear stresses. The produced particles had diameters ranging from 40 to 1700 µm. Reprocessing of the produced powder resulted in a narrower particle size distribution. Considerable heat generated in the extruder due to friction caused surface oxidation of the fine rubber particles and, in turn, initiation of agglomeration of a portion of the produced particles. Physical, chemical, and thermal analyses were performed on the produced rubber particles and the rubber granulates to determine the effects of the pulverization process. The produced particles had irregular shapes with rough surfaces. The external surfaces of the particles were porous, but no microporosity was detected by nitrogen BET analysis. Swelling and extraction experiments showed that both the crosslink density and gel fraction of the particles were lower than those of the rubber granulates. The reprocessing of the produced particles caused further reduction in the crosslink density and the gel fraction. A correlation was established between the crosslink density and the gel fraction. Thermal analysis revealed similar behavior of all particles and the granulates in a nitrogen environment, but there was considerable thermo-oxidative degradation of the fine particles in air. The chemical analysis indicated that some of the bonds were broken during the pulverization process, and partial devulcanization had taken place.
Bromination of Butyl Rubber in the Presence of Electrophilic Solvents and Oxidizing Agents
Authors: Kaszas Gabor 
Published: February 2011

Abstract
Bromination of 1,4-isoprene units in butyl rubber proceeds by substitution leading to the formation of hydrogen bromide as byproduct. In-situ conversion of HBr back to bromine is possible by the use of oxidizing agents but the reaction is very slow and oxidation of the polymer may occur. The reaction is complex and is typically conducted in a two-phase system. It has been found that the rate-controlling step is the bromination of the 1,4-isoprene unit in the organic phase, and not the oxidation of HBr to Br2 in the water phase or the mass transfer of HBr or Br2 between phases. Increasing the electrophilicity of the organic phase dramatically increased the overall rate. A 90–95 wt % conversion of bromine was achieved in one minute. Side or consecutive reactions (oxidation of the polymer, hydrobromination of the unsaturation, rearrangement or dehydrohalogenation of the main product) could be avoided, allowing the synthesis of a highly uniform material.