bluuebunny/crossref_metadata_2025_split huggingface dataset:
Room-Temperature-Cured Polydimethylsiloxane Elastomers from Aqueous Dispersion
Authors: Saam J. C. , Graiver D. , Baile M. 
Published: February 2011

Abstract
The observations are consistent with the formation of grafts of hydrophilic silicates to the silanol chain ends at the surface of the PDMS emulsion particles prior to removal of the water. The silicates may be introduced into the system directly or through the alkaline colloidal silica, which contains appreciable amounts of dissolved silicates. Monomeric, or possibly dimeric, silicate grafted to more than one chain end could migrate to the interior of the PDMS emulsion particle to form further crosslinks. Grafts to higher molecular weight silicates and silicate grafts bearing anionic charge would be solvated with water and tend to remain at the oil-water interface. This could provide steric as well as ionic stabilization to the PDMS particles, and the system would no longer respond to electrolytes as a simple, ionically stabilized, hydrophobic colloid but more as a hydrophilic colloid resembling silica. The role of the dioctyltin dilaurate is to interact in the water phase with the water-soluble silicates to render them, in effect, hydrophobic and to transport them to the oil-water interface. There the dialkyltin species can catalyze condensation between silanol on the silicate with silanol on the PDMS chain ends. Alkyltin acylates are known to hydrolyze in aqueous alkaline media, and the product can condense with silanol on the silicate to form silastannoxane intermediates. These are relatively stable to hydrolysis, provided bulky groups are present on tin as in dioctyltin dilaurate.
An Overview: New Ideas in Nondestructive Evaluation
Authors: Berger Harold 
Published: February 2011

Abstract
It is recognized that present methods for NDE of tires emphasize x-radiography, ultrasonics, and holographic interferometry. Modifications of these approaches in terms of improved signal processing, image magnification (for x rays), electronic focus (for ultrasonics), and tomographic imaging appear to offer promise for improved NDE of tires. In addition, techniques such as acoustic emission, pulsed eddy currents, microwaves, and vibrothermography also show promise. The suggestion that other NDE methods now being investigated for application to composite structures be followed closely appears valid as does the concept of improved procedures to verify the condition of raw materials used in initial fabrication.
The Influence of Carbon Black on the Reversion Process in Sulfur-Accelerated Vulcanization of Natural Rubber
Authors: Chen C. H. , Koenig J. L. , Shelton J. R. , Collins E. A. 
Published: February 2011

Abstract
The effect of carbon black upon the reversion process in the sulfur-accelerated vulcanization of natural rubber has been studied. It is found that black-filled cure systems have a faster rate of vulcanization and better reversion resistance. The net decrease of trans-methine content, which is equivalent to the improvement of reversion resistance, is found to be at most 15%, with the initial 10 pphr loading yielding the greatest effect. However, those decreases of trans-methine content are small when compared with the substantial effects of these fillers on the physical-mechanical properties of the vulcanizate, which is a linear function of black loading. In general, the smaller the black particle size, the greater the improvement of the reversion resistance, but particle size alone is not the only factor affecting reversion. A universal curve is obtained for correlating the amount of reversion and trans-methine content, which is independent of any natural rubber-based curing system, operating conditions and type of fillers.
Degradative Studies Related to the Plasticity Retention Index of the Standard Malasian Rubber Scheme. I. Kinetics of Degradation
Authors: Sambhi Manjit S. 
Published: February 2011

Abstract
Molecular degradation is the main process occurring during the high temperature oxidative aging of most commercial grades of natural rubber. The degradation as measured in terms of Wallace plasticities exhibit first-order kinetics for about 50% extent of degradation. PRI can now be expressed in terms of the first-order rate constant of degradation and is independent of the initial plasticity of the rubber. The observed first-order behavior has been explained in terms of linear intrinsic viscosities versus Wallace plasticities. PRI can be interpreted in terms of the molecular chain length. Complications can, however, arise if hardening of the rubber can occur concurrently with degradation during the PRI test. We then obtain inflated PRI values which overestimate the abilities of the rubbers to resist molecular breakdown, if PRI is considered to arise from degradation only. Perhaps, in order to nullify any possible hardening contribution to PRI values, the PRI test could be designed for rubbers which have undergone some form of controlled accelerated storage-hardening in a manner that prohibits oxidative degradation.
Formation and Structure of End-Linked Elastomer Networks
Authors: Dušek Karel 
Published: February 2011

Abstract
The network structure of end-linked polymer networks prepared from telechelic polymers is determined mainly by the functionality distribution of the telechelic polymer, the relative reactivity of the functional groups, and the conditions of network formation. The main feature of network formation by end-linking (by a step reaction) is a relatively high critical conversion at the gel point and a relatively narrow range of conversions available for the build-up of the network structure. Therefore, the final equilibrium properties (modulus and degree of swelling) are rather sensitive to cyclization, incompleteness of the reaction, and possible errors in the determination of the content of functional groups or functionality. The wastage of bonds in elastically inactive cycles is rather low, amounting to several per cent, but its effect on the concentration of EANC's is not negligible. In multicomponent systems, where two or more structurally differing components contain groups of the same kind, chemical clustering (e.g., formation of hard clusters) occurs and affects the concentration of EANC's as well as a number of physical properties. For polyurethane networks, mechanical, dielectric and optical measurements indicate that networks of poly(oxypropylene)triol and diisocyanate are more homogeneous than those of poly(oxypropylene)diols, 1,1,1-trimethylolpropane, and diisocyanate, and that the two-stage process yields more homogeneous networks than the one-stage one. The correlations between the concentration of EANC's and the gel fraction can be generalized and employed in examining the rubber elasticity theories or the degree of crosslinking of industrially important elastomer networks. In addition to the common features, the endlinking processes have their own specificities given by differences in the crosslinking mechanisms and, sometimes, in physical interactions. An example of a more complex network formation (and a correspondingly more difficult theoretical treatment) is crosslinking of carboxyl-terminated rubbers with diepoxides.
Scanning Electron Microscopy Studies of Tear of Carboxylated Nitrile Rubber
Authors: Chakraborty S. K. , Bhowmick A. K. , De S. K. , Dhindaw B. K. 
Published: February 2011

Abstract
Mechanism of tear of unfilled and carbon black filled carboxylated nitrile rubber (XNBR) having metallocarboxylate crosslinks, sulfur-sulfur crosslinks and mixed type crosslinking systems has been studied by Scanning Electron Microscope. Tear proceeds through stick-slip process in the case of gum mixes. The number of tear lines is more in the sulfur crosslinked system, resulting in poor tear strength. Addition of reinforcing carbon black changes the mechanism of tear. The sulfur crosslinked system shows knotty tear, while introduction of ionic crosslinks results in smooth tear presumably due to the large tip diameter reaching the edge of the specimen.
A Direct Experimental Determination of the Elastic Contribution of Chain Entangling in a Tightly Crosslinked Elastomer
Authors: Batsberg W. , Kramer O. 
Published: February 2011

Abstract
The experimental result, that the equilibrium force is nearly equal to the pseudoequilibrium force immediately prior to quenching and irradiation, allows the following conclusions: (1) Chain scission during crosslinking is not a serious problem. (2) The network of highly entangled linear chains is effectively at elastic equilibrium immediately prior to crosslinking in the strained state. This would not be the case if the entangled structure remained untrapped. (3) The effect of chain entangling in tightly crosslinked elastomers is large, also at elastic equilibrium. In fact, it is almost quantitatively equal to the pseudo-equilibrium stress relaxation modulus of the uncrosslinked linear polymer. This result is in agreement with the results from the Langley and the two-network methods.
Measurement of Tensile Strength of Natural Rubber Vulcanizates at Elevated Temperature
Authors: Bell C. L. M. , Stinson D. , Thomas A. G. 
Published: February 2011

Abstract
The tensile strength of test pieces made from natural rubber vulcanizates drops abruptly at a critical temperature which can vary from 40 to 130°C. This variation in critical temperature is shown here to be a result of the variation in critical cut length with temperature. When the naturally occurring flaws in the test piece are smaller than the critical cut length, high tensile strength values occur, but when the flaws are longer than the critical cut length, low tensile strength values occur. The critical cut length decreases as the temperature increases, and the abrupt drop in tensile strength occurs as the critical cut length reaches the natural flaw size in the test piece. The natural flaw size in tensile test pieces depends on the sharpness of the cutter, and for tensile strength measurements at elevated temperature, it is shown that even a slightly blunt cutter may give markedly different results from a sharp one.
Polytetramethylene Ether Glycol: Effect of Concentration, Molecular Weight, and Molecular Weight Distribution on Properties of MDI/BDO-Based Polyurethanes
Authors: Pechhold E. , Pruckmayr G. 
Published: February 2011

Abstract
Hardness, modulus, and tear strength of PTMEG-based polyurethanes are mainly affected by the hard-segment (MDI/BDO) concentration. On the other hand, PTMEG molecular weight mainly influences low-temperature and dynamic properties. Resilience and hydrolytic stability are affected by both soft-segment concentration and chain length. PTMEG of narrow molecular weight distribution yields softer polyurethanes with considerably longer elongation at break. Broad molecular weight distribution is advantageous only at the lower molecular weight range (650 and 1000), giving rise to improved resilience and low-temperature performance. Polyurethanes made from PTMEG of low molecular weight (Mn≤1000) have inherent drawbacks due to poor phase separation (high Tg) and limits in soft segment concentration (∼63% maximum for PTMEG 1000). The only advantage they offer is easier processability (lower viscosity and melting temperature). On the other hand, PTMEG above 2100 offers little property advantages and is more difficult to handle. Optimum overall polyurethane properties can be achieved with PTMEG in the molecular weight range of 1800 to 2100. It is conceivable that PTMEG-based polyurethanes made with different diisocyanates, curatives, curative/NCO ratios, or in the presence of triols or catalysts may show similar trends as the MDI/BDO formulations described in this study.
Fatigue Resistance of Natural Rubber in Compression
Authors: Lindley P. B. , Stevenson A. 
Published: February 2011

Abstract
Repeated deformation of natural rubber cylinders in compression causes cracks to initiate at points of maximum tensile stress concentration (e.g., at bond edges). These cracks grow until all the rubber which at the maximum deformation bulges outside the original profile of the cylinder is removed. Crack growth rates (da/dN) and strain energy release rates (G) have been determined. G is substantially independent of crack length. The relation between da/dN and G appears to be a fundamental material property for use in the determination of fatigue lives. Shaping the force free surface improves fatigue resistance.
Optimization of Rubber Mixing in Internal Mixers
Authors: Wiedmann W. M. , Schmid H. M. 
Published: February 2011

Abstract
Conventional rotor geometries of both the tangential and intermeshing systems can be improved in regard to working volume, feeding, mixing result, and milder temperature-rise. However it is necessary to consider both systems to supplement each other: (1) The tangential system is primarily for high machine efficiency, fast feeding, fast discharge and fast incorporation, i.e., for short mixing cycles and for multi-stage mixing. (2) The intermeshing system is for problems with distribution and temperature and for the increased theoretical output with longer mixing cycles by decreasing the number of mixing stages. Theoretical and experimental analysis of the influence of various operating parameters makes it possible to produce an optimum batch. The end result is process control which improves batch-to-batch uniformity.
The Application of Thermogravimetry (TG) to the Characterization and Quantitative Determination of Carbon Blacks
Authors: Charsley E. L. , Dunn J. G. 
Published: February 2011

Abstract
(1) The experimental variables which are found to affect significantly the measured T15 value for compounded carbon blacks are: (a) the maximum temperature achieved during the pyrolysis step and (b) the flow rate of air and the heating rate used during the oxidation step. (2) There is a definite correlation between the T15 value and the surface area of a carbon black, both in its free form and when compounded in a rubber. The T15 value is dependent on the cure method of the rubber and has also recently been reported to depend on the manufacturing source of the carbon black. This technique, therefore, cannot be recommended as suitable for the identification of a carbon black type in an unknown formulation. It can be used, however, as a routine quality control check on batch rubbers. (3) Thermogravimetry can be used as a rapid and accurate method for the determination of the carbon black content of rubbers, at levels as far apart as 0.1% and 30%.
Tackification Studies of Natural Rubber/Styrene-Butadiene Rubber Blends
Authors: Copley Bruce C. 
Published: February 2011

Abstract
A 50:50 blend of NR and SBR 1011 is heterogeneous. When tackified with a resin which is compatible with the NR phase, but not the SBR phase, the resin appears to partition unequally between the NR and the SBR. The resulting heterogeneous pressure-sensitive adhesives exhibit very broad storage modulus transition zones. The increased breadth occurs predominantly at the lower frequency portion of the transition. This is quite different from the NR/SBR blends tackified with a resin which is compatible with both NR and SBR. The NR/SBR blend with compatible resins exhibits a single sharp transition which is similar in character to either pure NR or pure SBR adhesives prepared with completely compatible resins. The differences due to heterogeneity are clearly manifested in the mechanical properties of the blend and are reflected by the rolling ball tack and shear strength to steel properties. Rolling ball tack data are consistent with the hypothesis that the NR phase is more highly tackified than is the SBR phase. Shear adhesion to steel data further support this conclusion.
Fundamental Flex Fatigue Studies of Tire Sidewall Materials
Authors: Young D. G. , Kresge E. N. , Wallace A. J. 
Published: February 2011

Abstract
1. Material, fabrication, and operating variables can be separately evaluated by the tearing-energy approach, and selection decisions are improved. 2. Results from a wide variety of laboratory and sevice conditions can be analyzed and compared by this general methodology. 3. Certain CIIR blend black sidewall compounds have inherent flex fatigue advantages over NR/BR compounds mainly due to their high levels of tearing energy sustainable before crack growth will begin. 4. The empirical approach used gives satisfactory cut-growth functions over a wide range of conditions with no need to assume the form of the function in advance. 5. Conventionally run fatigue-life experiments can be primarily influenced by maximum natural flaw sizes present and will not satisfactorily predict sidewall performance.
Analytical Characterization of Tackifying Resins
Authors: Lattimer R. P. , Hooser E. R. , Diem H. E. , Rhee C. K. 
Published: February 2011

Abstract
Phenolic resins are added to rubber compounds to improve the tack (or autohesion) characteristics. These resins are generally oligomers of alkylated phenols and formaldehyde. Analytical characterizations of these resins are very limited and incomplete in the open literature. We have examined several types of resins using mass spectroscopy (principally field desorption, FD-MS), liquid chromatography (LC), and infrared spectroscopy (ATR-IR). Several oligomeric series were identified by FD-MS in t-octylphenol and t-dodecylphenol resins. ATR-IR analysis showed that the t-octyl groups are essentially completely p-substituted on the phenolic ring. LC was only of limited utility in obtaining analytical separations of resin oligomers. Higher molecular weight oligomers (≿1500) showed little if any LC resolution. Resins prepared under different manufacturing conditions showed additional series of oligomers. These were either “cyclic ethers” and/or amine-containing compounds, depending on the synthetic procedures used.
Energy Balance and Heat Transfer in Mixing of Elastomer Compounds with the Internal Mixer
Authors: Nakajima N. , Harrell E. R. , Seil D. A. 
Published: February 2011

Abstract
An energy balance was obtained for mixing of an elastomer compound in the internal mixer. The mixing operation was done reproducibly, and pertinent data were collected with relatively simple instrumentation. Out of the total mechanical energy input into the compound, 41–46% went to raise the temperature of the compound, and 40–45% was removed by the cooling water. The heat loss from the mixer wall to the room was very small and negligible. This energy balance is based on the average temperature profile, which assumes uniform temperature of the stock. The actual temperature measurement of the stocks gave temperature differences of as much as ±13.5°C, indicating temperature nonuniformity within the stock. This is very plausible because rubber is a poor conductor, the shear field within the mixing chamber is exceedingly nonuniform, and thus, the viscous heating of the material is very nonuniform. Heat transfer coefficients were evaluated for the overall heat transfer from the stock to the cooling water and for the heat transfer from the stock to the chamber wall. The data indicate that the compound was not uniform in the beginning of the mixing, in spite of the fact that a premixed powdered rubber was used. The nonuniformity must be in the degree of incorporation of carbon black rather than in the composition. There is also nonuniformity in the temperature. The heat transfer coefficient has a high value when the carbon black is on the surface of rubber but decreases to a constant value with the incorporation of carbon black into the rubber. Although it is not the objective of this paper to evaluate the effectiveness of mixing, the compound after curing gave mechanical properties which indicated thorough mixing.
Electron Microscopical Examination of Worn Tire Treads and Tread Debris
Authors: Smith R. W. , Veith A. G. 
Published: February 2011

Abstract
Tire wear is an important phenomenon, and the industry needs to know as much as possible about the mechanism of rubber abrasion that results in wear. A wealth of information can be obtained by studying tread surfaces and debris particles using the scanning electron microscope, energy dispersive x-ray analysis, and transmission electron microscopy of ultrathin sections. Such an examination was conducted on the worn tread surface of an SBR compound containing 75 phr N285 carbon black and 45 phr oil. A liquid-like layer composed of an intimate mixture of degraded rubber and road silt could be seen on the worn tread surfaces. The thickness of this layer is variable but generally in the micron and submicron region, except where it had been rolled up and was about to be thrown off as a debris particle. A general examination of NR and BR tread compounds revealed a similar appearance. Several collections of rubber debris particles were also examined and found to have the same composition of degraded rubber and road silt that was observed on the tread surface. These observations are in agreement with the results of Boonstra, Heckman, and Kabaya with respect to the analysis of road silt materials on tread surfaces. Since the silt is within the thin layer of degraded rubber, it cannot be washed off the tread surface with soap and water. It can be removed with benzene swabbing. In addition, this report provides visual documentation of tire wear that serves to support previous speculations. These results emphasize the importance of considering the abrasion of tire treads as a three-bodied system: the tread compound, the road surface and the layer between the two, which is composed of an intimate mixture of degraded rubber and road silt. Previous references to the presence of road silt particles on worn tread surfaces implied their incidental nature. This study shows that road silt penetrates into and becomes a part of the substructure of worn tread surfaces. Furthermore, the internal morphology of this substructure is identical to the morphology of the tread debris thrown off from the tread surface.
Configuration of the Brass on Brass-Plated Steel Wires in Tire Cords
Authors: Giuffria Ruth , Marcelli Angela 
Published: February 2011

Abstract
Study of the brass configuration on wires from a number of cords from different sources shows that the brass on all of the wires is highly nonuniform in its distribution. It is not a “layer” as the word is generally understood. In some areas, the steel is almost bare; in some areas, brass coverage may be 0.1–0.2 µm thick; in still other areas there are “intrusions” of brass extending into the steel much more than a micrometer. It is believed that this brass configuration is typical of all steel wires which have been drawn after brass plating; hence, it is probably typical of all wires currently used in brass-plated steel tire cord. Consideration should be given to this erratic brass configuration in studies of adhesion of tire rubber to brass-plated steel tire cord. Perhaps the current model(s) should be modified to include the possible effect of the reservoirs of brass in the “intrusions” which exist in the steel.