bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between Viscoelastic Properties and Characteristics of Filler-Gel in Filled Rubber System
Authors: Yatsuyanagi Fumito , Kaidou Hiroyuki , Ito Masayoshi 
Published: February 2011

Abstract
The wide-line NMR and viscoelastic measurements were carried out for the filled rubber systems. NMR results revealed that the filler-gel in the filled rubber composites had a multi-component system depending on the mobility of rubber molecules. The fraction and the spin-spin relaxation time of each component were well correlated with the viscoelastic properties such as dynamic storage modulus (E′) and loss-tangent (tan δ) of the filled rubber systems. Such findings turned out to be useful in designing new tread materials with well-balanced wet traction and rolling resistance in tires.
Modeling of Carbon Black Filled Natural Rubber Vulcanizates by the Standard Triboelastic Solid
Authors: Coveney V. A. , Johnson D. E. 
Published: February 2011

Abstract
Mathematical modeling of the dynamic behavior of vulcanizates is reviewed with the emphasis on carbon black filled natural rubber (NR). The 3 constant standard triboelastic solid (STS) model and its behavior are described, in general terms and with specific reference to low frequency shear data for a wide range of filled NR vulcanizates. Good general agreement is found between model and experiment for the data obtained at strain amplitudes down to 0.01; there is also acceptably good correlation between carbon black loading and values of STS constants. For previously published data down to very low strain amplitudes (1×10−4), agreement is much less satisfactory.
Elastomer-Elastomer Autohesion-Interphase Gradient of Elastic Modulus
Authors: Vallat M. F. , Giami S. , Coupard A. 
Published: February 2011

Abstract
The effect of migration on the vulcanizing ingredients is considered when two sheets of carbon black reinforced polyisoprene are brought into contact. Two formulations (conventional and efficient ones) are chosen. The formation of macroscopic interphases on both sides of the interface is shown by measurements of local modulus by microindentation. The local concentration of sulfur is determined by energy dispersive X-ray analysis. Near the interface, the modulus is always higher than in the bulk of the sheets although the interfacial strength may be quite low. Co-crosslinking of the chains in the interphase at the molecular level and macroscopic thick interphases are two important aspects of elastomer-elastomer joints.
Long-Chain Branching and Mechanism Controlling Molecular Weight in Hevea Rubber
Authors: Sakdapipanich Jitladda Tangpakdee , Kowitteerawut Tippawan , Suchiva Krisda , Tanaka Yasuyuki 
Published: February 2011

Abstract
The linear character of transesterified deproteinized natural rubber (DPNR-TE) was confirmed by the analysis of terminal groups with NMR and viscometric analyses. The branch content of DPNR rubber from fresh latex was found to range from 0.3 to 1.3 and 0.7 to 3.2, based on tri- and tetra-functionalities, respectively. The plot between the number of branch-points and molecular weight (MW) can be divided into three fractions: (A) the rubber fractions in MW ranging from 2.4×105 to 1.9×106; (B) between 1.9×105 and 2.4×105; and (C) those of MW less than 1.9×105. The fraction (A) showed the number of branch-points per a branched molecule (m) higher than that of fractions (B) and (C). This plot is superimposable with the bimodal molecular-weight distribution (MWD) of Hevea rubber, showing a good coinciding of peak-tops at the high and low MW fractions. It seems likely that there is a close relationship between the number of branch-point and bimodal MWD of natural rubber.
Tensile Behavior after Oxidative Aging of Gum and Black-Filled Vulcanizates of SBR and NR
Authors: Hamed G. R. , Zhao J. 
Published: February 2011

Abstract
Typical sulfur-cured vulcanizates of styrene-butadiene rubber (SBR) and natural rubber (NR) were prepared, and subjected to air-oven aging at 100 °C. Gum specimens exhibited an initial aging period in which stiffness was unchanged, while tensile strength and strain-to-break were significantly reduced. In contrast, black-filled vulcanizates stiffened during early aging. After intermediate aging times, NR specimens softened, while SBR stiffened. With prolonged aging, all compositions became hard and inextensible.
Modeling Dispersive Mixing of Rubber Compounds
Authors: Clarke J. , Petera J. 
Published: February 2011

Abstract
With the ultimate aim of improving mixer geometry by using a mathematical model for rubber mixing, this paper concentrates on the dispersive mixing process of filler disagglomeration. Specially designed elongational flow experiments were used to achieve dispersive mixing under conditions of known stress and strain rate history. It was found that the disagglomeration process is satisfactorally described by a first order differential equation with the rate constant proportional to the power density experienced by the compound during mixing. The kinetic model was implemented in original finite element software to obtain a 2-dimensional simulation of mixing in a twin rotor internal mixer. It was concluded that the 2-dimensional simulation was not only a necessary precursor to 3-dimensional modeling, but would in itself be useful for relating cross-sectional rotor geometry to efficiency of filler disagglomeration, and hence, dispersive mixing.
Fourier Transform Raman Spectroscopy for Characterization of Natural Rubber Reversion and of Antireversion Agents
Authors: Datta R. N. , Hofstraat J. W. , Geurts F. A. J. , Talma A. G. 
Published: February 2011

Abstract
Fourier Transform Raman spectroscopy is employed to study the mechanism of reversion and the influence of the antireversion agent, 1,3 bis(citraconimidomethyl)benzene (BCI-MX) in squalene as well as in low molecular weight synthetic polyisoprene. The formation of non-sulfidic main chain modifications, such as conjugated diene and triene units, along the squalene and isoprene backbone is followed by using this technique. The mode of action and the efficacy of BCI-MX is studied. The decrease in concentration of conjugated diene and trienes by the addition of BCI-MX confirms the reaction of BCI-MX with polyenes to be a Diels-Alder reaction. In addition to the detection of reversion reactions also other processes which occur during rubber vulcanization are monitored via Raman spectroscopy.
Devulcanization of Guayule Rubber by Ultrasound
Authors: Gonzalez-de los Santos Eduardo A. , Soriano-Corral Florentino , Lozano-Gonzalez Ma Josefina , Cedillo-Garcia Rodrigo 
Published: February 2011

Abstract
The present study describes the effect of ultrasonic irradiation on vulcanized guayule rubber using 1 to 3.5 parts per hundred of rubber (phr) of sulfur as the crosslink agent. The effect on crosslink density, gel fraction, torque and glass transition temperature was measured. After exposure to different powers of ultrasonic irradiation, the devulcanization effect was evident on the guayule rubber samples.
Phase Behavior of Brominated Poly(Isobutylene-co-4-Methylstyrene)/General Purpose Rubber Blends
Authors: Rabeony M. , Garner R. T. , Elspass C. W. , Peiffer D. G. , Lin M. , McElrath K. O. , Dias J. A. , Cross J. P. 
Published: February 2011

Abstract
The thermodynamic interaction and phase behavior of elastomeric blends, specifically brominated poly(isobutylene-co-4-methylstyrene) and a general purpose rubber, polybutadiene, have been examined using small-angle neutron scattering (SANS) and cloud points measurements. The low molecular weight equivalent of each segment was used to produce a single phase blend from which the Flory-Huggins interaction parameter (λ) was extracted. The results were analyzed using the random copolymer formalism. The results show that the “repulsive” interaction between the isobutylene and 4-methylstyrene monomer units enhances the compatibility of brominated poly(isobutylene-co-4-methylstyrene) with polybutadiene. A maximum in compatibility occurs at approximately 50 mol % 4-methylstyrene. This fundamental information is essential for the determination of the phase behavior of these materials, and their regions of miscibility/immiscibility. In addition, this information can be used to calculate the optimum copolymer composition for this scientifically interesting and technologically important blend system.
Surface Structure of Carbon Black and Reinforcement
Authors: Göritz Dietmar , Raab Horst , Fröhlich Joachim , Maier Peter G. 
Published: February 2011

Abstract
From scanning tunneling microscopy (STM) and atomic force microscopy (AFM) measurements, it was found that the lateral dimensions of the nanocrystallites systematically decrease with decreasing diameter of the primary particles. Furthermore these experiments suggest that these nanocrystallites, unregularly tilted, form the rough surface of carbon blacks. Hence, the activity of carbon black is the result of the size of the nanocrystallites and the degree of disorder on the surface. Temperature treatments of carbon black lead to a continuous increase of the lateral dimensions of the crystallites and a steady decrease in roughness. In order to quantify the surface roughness small-angle X-ray scattering (SAXS) measurements, that spanned a large scattering vector range, were evaluated by a fractal analysis. The surface fractal dimensions systematically increased with rising activity of the carbon black. Reinforcement is discussed within the scope of interaction of network chains with the carbon black surface. For this purpose, the dependency of the Payne effect on temperature, prestrain and swelling is interpreted using an adsorption mechanism of network chains on the surface of the filler particles. This mechanism requires the existence of stable and unstable bonded chains. Only the weakly bonded chains seem to be responsible for the Payne effect.
The Mechanism of Carbon Black Reinforcement of SBR and NR Vulcanizates
Authors: Hamed G. R. , Park B. H. 
Published: February 2011

Abstract
Gum and black-filled vulcanizates of styrene-butadiene rubber (SBR) and natural rubber (NR) were prepared. Strengths in uniaxial tension were determined for specimens with and without edge-cuts. Normal tensile strengths (no cut) of the gum NR, filled NR and filled SBR were similar; whereas, with pre-cuts, even as small as 0.1 mm, strengths of these were markedly different. The SBRs exhibit a steady decrease in strength with increased cut size, while the NR vulcanizates show a drop in strength at a critical cut size ccr. With small cuts, when the gum NR substantially crystallizes in bulk, its strength greatly exceeds that of the filled SBR. The opposite is true with large cuts, due to the large drop in strength of gum NR at ccr. Remarkably, above ccr, the gum NR is only about twice as strong as the gum SBR. Rupture in the gum SBR, gum NR and filled SBR all take place by simple lateral cut growth. At all cut sizes, the filled NR is the strongest material by at least a factor of two, and prior to catastrophic fracture it exhibits auxiliary cracking. It is proposed that crystallization and filler act synergistically, resulting in sufficient anisotropy to cause longitudinal cracking. This provides a super-blunting mechanism, which augments resistance to catastrophic cut growth.
Improved Tire Wet Traction through the Use of Mineral Fillers
Authors: Mouri Hiroshi , Akutagawa Keizo 
Published: February 2011

Abstract
Silica is widely used in passenger tire treads to improve the balance between wet traction and rolling resistance, compared to the balance achieved when the filler is strictly carbon black. Improvement in wet traction with silica is attributed to the difference in energy loss encountered at high frequencies. The energy loss difference is deduced from the difference in shift factors, determined by time temperature superposition in viscoelastic testing of silica compounds compared to carbon black compounds. Further investigation indicated that some mineral fillers other than silica showed similar behavior. Thus, some mineral fillers could improve tire wet traction without adverse effects on other tire performance traits.
Mechanism of Peroxide Vulcanization of Elastomers
Authors: Loan L. D. 
Published: February 2011

Abstract
As is now well known, the use of an organic peroxide as a crosslinking agent for an elastomer was first reported by Ostromislensky in 1915. In this work benzoyl peroxide was used to cure natural rubber; similar acyl peroxides together with more recently discovered, less active, and more convenient dialkyl peroxides have since this time been used to crosslink a very large number of polymers. With the common unsaturated polymers the vulcanizates produced have mechanical properties rather inferior to those obtained with accelerated sulfur cures. They do, however, have the good aging and low compression set properties which are, in general, associated with sulfurless cures. The commercial use of peroxides in unsaturated elastomers is nevertheless small, being employed only where the presence of sulfur would be deleterious. In spite of its technological disadvantages peroxide crosslinking has been extensively studied since it forms a chemically simple means of introducing crosslinks into a wide variety of rubbers and leads to vulcanizates of simple structure with physically and chemically stable, carbon-to-carbon crosslinks. Interest in the industrial use of peroxides as curing agents has increased recently with the introduction of a number of fully saturated rubbers for which the usual accelerated sulfur systems are unsuitable. Such saturated rubbers are, in general, more resistant to aging, are more thermally stable, and will probably be used to increasingly greater extents as operational conditions become more and more severe. The study of curing systems available for use with such rubbers is therefore of considerable importance and organic peroxides, forming one such system, are worthy of detailed examination. Much work has been done on the technological evaluation of peroxide vulcanizates and much of this is summarized in a recent book edited by Alliger and Sjothun which is recommended as a source of references for a more detailed study of this aspect of the subject. The basic mechanism of the peroxide crosslinking of a wide variety of rubbers has, however, been neglected until relatively recently. For this reason, and for reasons of length, it is proposed to limit the present review to this latter aspect of the subject.
Thermodynamics of Non-Dilute Polymer Solutions
Authors: Patterson D. 
Published: February 2011

Abstract
An excellent new text, “Macromolecules in Solution,” by A. Morawetz emphasizes advances in polymer solution thermodynamics since publication of standard texts such as those of Tompa and Flory. Detailed development of the subject from 1950 may be followed in articles on polymers in Annual Reviews of Physical Chemistry, and particularly in the articles appearing every three years specially devoted to solution properties: Flory and Krigbaum (1951), Wall and Hiller (1954), Hermans (1957), Casassa (1960) and Hughes and von Frankenberg (1963). The articles on solutions of non-electrolytes are, of course, always of general interest and often deal directly with polymer solutions or mixtures of chain molecules. Because of this very satisfactory situation, the author has decided that the best thing is to review in more detail the single topic which is most interesting to him. This is the thermodynamics of non-dilute solutions where it is usually supposed that the quasi-lattice theories of the 40's are quite adequate at concentrations greater than about 10 per cent. For fifteen years or so, interest has centered on very dilute polymer solutions and the dimensions of isolated polymer molecules, particularly at temperatures near the θ point. Increasingly difficult mathematical problems have followed the McMillan-Mayer comparison of solutions and imperfect gases first applied to polymer solutions by Zimm and Stockmayer. Polymer solution thermodynamics seems to have moved far beyond the intuitive questions of Meyer as to why a polymer solution differs from an ideal solution or from a mixture of a monomeric solute and solvent. However, certain results, apparently not very widely known, make one feel that such qualitative questions are not out of date and that the thermodynamics of concentrated polymer solutions may be open to much further development.
Analysis, Composition and Structure of Rubber and Rubber Products
Authors: Tyler Wlllard P. 
Published: February 2011

Abstract
Seven years has passed since the review of methods of analysis of rubber and rubber products by Burger was published in this Journal. At that time the author covered a broad field of endeavor with special emphasis on classical methods of analysis. He also foresaw the future of instrumental techniques, many of which were only beginning to be useful in rubber chemistry. The questions that must be answered today seem to us, from the vantage point of seven years of remarkable progress, to be more complex. Which new techniques have proved to be most useful in helping the analytical chemist to solve daily problems of analysis of his own and his competitors' products? Which techniques are giving him a tool to study the relation between composition, structure, and properties of rubbers? Which techniques can help the polymer chemist to better chart his course in the search for new and better elastomers? The new techniques, and a few of the old ones, have advanced so rapidly in the last decade that it is presumptuous to think that we can answer these questions completely in a review paper. What, then, is the purpose of this review? We could prepare a complete bibliography and comment briefly on the more important papers. But this has been adequately done, with a very broad scope, in the reviews appearing in Analytical Chemistry every two years. We feel this approach would be redundant. We have chosen, instead, to attempt to cover available techniques from the standpoint of what can be done with them in several important areas, using key papers from the literature as a basis. Our added comments are the result of years of experience in the ceaseless quest for the best use of analysis and structure-determining tools in advancing research, development, and production in the field of elastomers.
Heat Transfer in Processing and Use of Rubber
Authors: Gehman S. D. 
Published: February 2011

Abstract
Heat transfer in rubber is likely to be significant from the first processing steps to the end use of the product. At the start, it is encountered in preparing, drying, and handling raw polymers; then in mixing and forming or molding compounds. In this stage, the thermoplastic nature of rubber is such that viscosity and other physical characteristics are especially temperature sensitive. Heat is the most important processing agent. The rate at which heat can get into and out of rubber, how expertly it can be transferred, affects the design of processing machinery and controls the speed of many mixing, extruding, and molding operations. In these processes, primary, turbulent heat transfer between rubber and steel and mass transfer in the rubber are complicated by frictional heat generation at the rubber-metal surfaces and large conversion of mechanical energy into internal heat. Convection heat transfer with air, steam, or fluids also usually occurs in processing rubber. Localized overheating at any stage can be disastrous for quality. Hence the basic heat problems in processing usually lie in rapidly and efficiently securing, and then maintaining, satisfactory temperature uniformity in a material with inherently poor heat transfer characteristics. Dispersing fillers in rubber requires large power inputs but the resulting temperature rise must not be so great as to cause prevulcanization or reduce unduly the efficiency of the mixing operation by too great reduction in plasticity and hence shearing stresses. On the other hand, Hahn has pointed out how advantageous such mechanical heating of rubber may be. A few minutes working on a mill may accomplish more in raising the temperature than hours of conduction heat flow. After rubber is mixed and formed, vulcanization ensues with flow of heat to raise the temperature throughout to the vulcanization range and thus activate the chemical reactions of vulcanization. At this stage, control of heat is exceedingly important for costs and quality. Any shortening of the vulcanizing cycle without detriment to quality provides opportunity to increase productivity of a large capital investiment. Finally, heat is one of the most destructive agents for finished rubber products. It presents a frontier for development of new rubbers and applications. External environmental heat imposes service limitations and in dynamic uses involving repeated, rapid deformations internal transformation of mechanical energy into heat may readily destroy thick rubber sections.
Displacement of Elastomers from Carbon Gel in Filled Mixes
Authors: Craig David 
Published: February 2011

Abstract
Bound rubber may be displaced by milling filled hydrocarbon elastomers with polar rubbers such as NBR. The displacement is not complete in a single stage. Crosslinking can be detected in filled natural rubber by moderate swelling and then measuring the freezing point depression caused by the rubber in the filled and unfilled state, a greater depression being observed for the filled state. Filled and unfilled CB at the same concentration in benzene seems to cause the same freezing point depression and so crosslinking during the reinforcement of this rubber, though known to exist from other behavior, seems not to be indicated by the freezing point method.
Rates of Crystallization of cis-1,4-Polybutadiene in Elastomer Blends
Authors: Morris M. C. 
Published: February 2011

Abstract
Blends of polybutadiene with SBR show different crystallization behavior than blends with polyisoprene. One might suppose that the similarities in SBR and polybutadiene are sufficient to allow more intimate mixing than can be obtained by using entirely different polymers such as the polyisoprene polybutadiene pair. Possibly, bulk viscosities are important here, but no matter what the cause, crystallization properties have shown differences in the way the polybutadiene was situated. Also, large changes in the glass transition occurred for those materials which showed sizeable retardation in crystallization rate. An interpretation of the crystallization rate data based on particle size was given in this discussion because a precedent exists for this effect. However, molecular compatibility has not been ruled out. Further investigation of thermal properties should help clarify this point. It will be interesting to learn to what extent particle size alone affects the thermal behavior of blends. Perhaps more work along these lines coupled with improved optical and electron microscope techniques will provide some answers to our questions on how phase structure affects thermal and mechanical properties.