bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solution-SBR Powders
Authors: Schulz D. N. , Calihan L. E. , Tate D. P. 
Published: February 2011

Abstract
This paper describes the advantageous cross-fertilization of solution-masterbatch technology and powdered-rubber processing. A nonlatex method has been developed for the preparation of free-flowing solution-SBR powders. The factors affecting powder particle size and morphology have been identified. Optimization of the preparative variables has resulted in dry-blendable solution-SBR powders. As a consequence of a low shear history, the solution-SBR powder blends show distinctive rubber-filler, rheological, and physical properties. For example, unvulcanized solution-SBR powder compounds evince higher molecular weights and lower bound-rubber contents than conventional mixes. Yet, the microscopic filler dispersion of these two types of compounds appears similar. Uncured solution-SBR powder blends also exhibit stiffer rheological behavior than conventional mixes. Furthermore, this stiffness tends to persist in the vuleanizates derived from these powdered compounds. Vulcanizate excellence depends primarily upon fineness of the powder particles and absence of free filler. Conditions have been found which permit the direct ribbon extrusion of tire tread, without prior compacting or milling. Conventional single-screw ribbon- tread extruders are sufficient to produce treads of high quality.
Processing in an Internal Mixer as Affected by Carbon Black Properties
Authors: Dizon E. S. 
Published: February 2011

Abstract
This paper has attempted to review current knowledge on mixing fundamentals from a carbon black standpoint. The mixing parameters discussed include volume fill factor, specific energy of mixing, temperature buildup, and flow characteristics. Together, these parameters define the economics of mixing in terms of mixing capacity, energy expenditure, limitations imposed by dump temperature on second-stage operations, and extruder flow requirements. The four parameters in turn were related to basic carbon black properties by way of mixing profiles. Ten currently available tread blacks which exhibit a wide range of tread wear resistance have been characterized in terms of the processability criteria. A processability rating system based on the most simple equipment requirement (a Banbury followed immediately by a second-stage mill or an extruder) was applied to the ten blacks. Comparison of the processability ratings with the tread wear ratings clearly demonstrates that a valid assessment of carbon black utility must include processing cost in addition to performance capability. As in many rubber properties, there is clearly an inverse relationship between performance quality and processability. High-structure, high-surface-area blacks that are desirable from a performance standpoint require the highest processing cost. The question of uniformity was also discussed, and it was concluded that the present specifications controlling carbon black surface area and structure are adequate in minimizing processing variations. The challenge to processing technology from a carbon black standpoint then involves the reduction in the cost of processing high-structure, high-surface-area blacks. At this stage, a quantitative measure of the processing characteristics of the currently available tread blacks at least allows a rational product selection in terms of optimum performance and processing cost. In the meantime, it is evident that significant advances in carbon black technology are still needed if performance optimization is to be reconciled with the economics of processing.
Effects of Molybdenum Disulfide on Elastomer Flex Life and Other Properties
Authors: Smith G. G. , Loban R. D. 
Published: February 2011

Abstract
The addition of 15–20 phr MoS2 to a typical radial tire compound provides significant benefits in processing, tack, physical properties, adhesion, and flex crack growth with minimal effects on cure, compression set, ozone resistance, weatherometer aging, or heat buildup. Although lower-cost additives are available that can provide a similar benefit in each area, few provide such multiple benefits.
Quantitative Evaluation of Emulsion Styrene-Butadiene Rubbers and Compounding Variables by Controlled Mixing
Authors: Turetzky S. B. , Van Buskirk P. R. , Gunberg P. F. 
Published: February 2011

Abstract
Work reported recently described a “unit work” concept, according to which the flow behavior of a rubber-carbon black mixture was shown to be a function of the mixing work input. These results were shown to be independent of the size of the mixer, the speed of the mixer, and mixing time so long as the temperature-time profiles were similar, the same loading procedure was employed, and the same loading volume percentages were used. This concept provides a means to characterize not only the effect of various polymers, extenders, fillers, and minor additives, but also the uniformity of a given major constituent, which, in the case of an elastomer, may be a processability index. The work described in this paper is the application of the unit work concept to some of these areas : emulsion styrene-butadiene polymers, extenders, and fillers. By means of this concept of mixing, laboratory investigation can be translated, not only qualitatively, but much more important, quantitatively, into factory operations. The effects of polymer molecular weight and bound-styrene content changes, as well as changes in carbon blacks, such as those typified by the new tread blacks, can be investigated in the laboratory, and compounding adjustments can be made there, so that factory production time is not taken for new compound development.
Tensile Strength of Polyurethane and other Elastomeric Block Copolymers
Authors: Smith Thor L. 
Published: February 2011

Abstract
The discussion in this paper has been focused on the strength of Polyurethane elastomers, data on other materials being presented for comparison and to illustrate factors that affect strength. Although the literature on Polyurethane elastomers is voluminous, only in recent years has it been widely recognized that plastic domains exist in most polyurethane formulations of technological importance. Evidence for domain formation and aspects of domain morphology are discussed in recent reviews. The morphology of domains in segmented polyurethane elastomers is more complex than of those in triblock elastomers and has not been studied extensively, although progress is being made, indicated by the discussions in recent publications and references cited therein. In view of the complexities of fracture and the limited information on the morphology and time-dependent mechanical properties of polyurethane elastomers, only general relations between strength and chemical structure have thus far been established. On the other hand, useful correlations can be established by considering the type, size, and concentration of the hard segments and whether strain-induced crystallization is a dominant factor.
The Effect of Temperature on the Stress-Strain Isotherms of Polyisobutylene Networks at High Elongation
Authors: Kato M. , Mark J. E. 
Published: February 2011

Abstract
Three chemically cured, unfilled polyisobutylene networks were studied in elongation to their rupture points at several temperatures in the range 15–80°C. At the lower temperatures, the stress-strain isotherms obtained were similar to those reported for unfilled networks of natural rubber and several other polymers in that they showed an anomalous, marked increase in the modulus or reduced force at high elongations. At intermediate temperatures, this upturn in the force is significantly diminished, however, and the networks rupture at lower elongations. At the higher temperatures, there is no evidence whatever for an upturn in the force, and the elongation at rupture is further reduced. These results on polyisobutylene networks implicate strain-induced crystallization rather than limited chain extensibility as the origin of the pronounced increase in the force at high elongations. The reinforcement provided by the crystallites formed in this manner would account for the increased extensibility of the networks at the lower temperatures. Since natural rubber is very similar to polyisobutylene in its crystallizability, the anomalous stress-strain isotherms widely reported for networks of this polymer are thus probably also due largely, if not entirely, to network crystallization.
Changes of State in Polymeric Networks during Orientation. II. Analysis of Elongation-Induced Crystallization by Calorimetry
Authors: Göritz D. , Müller F. H. 
Published: February 2011

Abstract
Studies of the elongation-induced crystallization have shown that crystallization during stretching follows a different mechanism than that in the extended state. The final degree of crystallization is found to be dependent on temperature and elongation. The dependence on elongation does not follow Flory's theory of crystallization induced by stretching polymeric networks. However, separating the crystallization into one process developing during stretching and another in the extended state shows that this theory applies to the latter one. Time analysis of the oriented crystallization on axial stress yields similar results. This crystallization cannot be described as a single uniform process by the theory of Avrami. However, by considering two separate processes, each can be described quantitatively with sufficient accuracy. The stress-induced crystallization is controlled by homogeneous formation of nuclei which grow three-dimensionally. After termination of stretching no further nuclei are formed. Further crystallization is restricted to one-dimensional growth of existing crystallites in the direction of stress. Both mechanisms of crystallization are independent of temperature, elongation, and degree of crosslinking.
Block Copolymers, Polymer-Polymer Interfaces, and the Theory of Inhomogeneous Polymers
Authors: Helfand E. 
Published: February 2011

Abstract
Most of the polymeric materials one encounters so widely are heterogeneous. For instance, commercial plastics may be blends of immiscible polymers; they may contain antioxidants or other modifiers which are not totally soluble; andfrequently they have added inorganic fillers. Other examples of inhomogeneity in polymer systems are composites, partially crystalline materials, surface layers, ionomers, and block and graft copolymers. In some cases the heterogeneity is the essence of the material's virtue (e.g., its mechanical properties). In other cases heterogeneity is an affliction. But, whether one's goal is to maximize or minimize the effect of nonuniformity, it is well to understand the factors which determine the features of inhomogeneous polymers. This we will attempt to do in a qualitative way by describing, from a simple molecular point of view, the entropy and energy terms which control the systems' physical features. Rather than dealing in generalities, however, let us focus on two particular cases : interfaces between immiscible polymers, and block copolymers. This should provide the reader with some insight into the myriad of recent developments in the field of polymer blends, composites, and microheterogeneities.
Coordination Complexes of 4,4′-Diaminodiphenylmethane—Chemistry and Applications
Authors: van Gulick N. M. , Verbanc J. J. , Caruso P. P. , Athey R. J. 
Published: February 2011

Abstract
Coordination complexes of 4,4′-diaminodiphenylmethane and alkali metal salts are effective delayed-action curatives for amine-curable polymers. In polyurethanes, particle size of the complex, the polarity of the reaction medium, and the isocyanate concentration of the polymer determine processing safety, curing temperature, and curing rate. Vulcanizate properties observed with polyether- and polyester-based cast urethane systems parallel those obtained with MOCA. Exceptions include the influence of residual salt, which increases water swell, and the presence of plasticizer, incorporated with predispersions, which lowers modulus and hardness slightly and influences solvent swell due to plasticizer extraction. The salt is bound in the vulcanizate and cannot be removed by simple water immersion. Alkali metal salt is liberated by hydrolytic destruction of the vulcanizate. Preliminary evidence suggests no increase either in corrosion of steel inserts embedded in urethane parts or in property loss during aging despite the presence of ∼1% residual salt.
Rheo-Optical Studies of Rubbers
Authors: Stein R. S. 
Published: February 2011

Abstract
It is evident that optical techniques can provide much information about the morphology, orientation, and phase transformations of homogeneous rubbers, rubber blends, copolymers, and composites. While no one method offers complete characterization, it is believed that the combination of these techniques can be of great value in the elucidation of these useful materials.
Reinforcing Silicas and Silicates
Authors: Wagner M. P. 
Published: February 2011

Abstract
Since the first intensive literature review on silicas and silicates was published, significant new technology for their use in rubber has developed. Usage in the rubber industry has broadened considerably, and increases in their consumption have occurred during the ensuing fifteen years. From the “soles and heels” fillers of the 1950's, the usage of precipitated silicas and silicates since has gained significantly in quality components of tires and mechanical goods. Potential applications in the immediate future are no longer limited by the “good, but second to carbon black” performance that has prevailed for the past twenty-five years. Besides the traditional unique properties of tear resistance, hardness, stiffness, flex resistance, heat resistance, low modulus, and neutral color imparted to rubber by silicas and silicates, it is now possible to add adhesion, low heat buildup, high resilience, high modulus, and high abrasion resistance. This is part of the new technology which has developed that provides an alternative type of filler to meet the demanding needs of tire components, conveyor belts, automotive mounts, gaskets and seals, and other quality rubber compounds previously inaccessible to silicas. The present review covers the period 1960–1975. Because of the volume of available literature, it became necessary to be quite selective, in a way perhaps that may seem arbitrary. Nevertheless, coverage will be confined largely to that relevant to more general rubber uses. Silicone rubber technology was not covered because of its highly specialized and generally proprietary nature. The definitions used in the previous review were expanded somewhat. Silicas and silicates (henceforth, “silicas”) germane to this review were generally restricted to those which are synthetic and amorphous. However, the size limitations were relaxed somewhat to include those having a specific surface area greater than 25 m2/g or an average particle diameter less than 100 nm. Natural products (e.g., clays, diatomaceous earth, sand, etc.), as well as their modified forms, were excluded.
Accelerated Heat-Aging Studies on Fluororubber in Various Media
Authors: Kalfayan S. H. , Silver R. H. , Liu S. S. 
Published: February 2011

Abstract
The nature, extent and, rate of chemical changes that take place in certain elastomers at long times is being studied. The chemical degradation of styrene-butadiene rubber (SBR) and fluorosilicone rubber (FVMQ) were reported previously. Investigations carried out with fluororubber (FKM) are discussed in this paper. Like fluorosilicone, this fluorocarbon elastomer is regarded as a high-temperature- and hydrocarbon-fuel-resistant rubber. The designation FKM is given to the copolymers of vinylidene fluoride (VF) and perfluoropropylene (PFP). The one discussed here is reported to contain also small quantities of a third component, tetrafluoroethylene. The detailed structure, assigned to the FKM polymer as a result of nuclear magnetic resonance studies, shows that it consists of blocks of VF homopolymer, 95% of which is head-to-tail, and blocks of VF-PFP copolymer, 93% of which is head-to-tail. The ratio of the copolymer to the VF homopolymer is dependent on the mole fraction of VF used. Vulcanization of FKM with derivatives of diamines is the commercially preferred method, although peroxides and high-energy radiation can be used for the same purpose. In the present study, N, N-dicinnamylidene-1,6-hexanediamine a Schiff 's base of 1,6-hexanediamine, was used with magnesium oxide as the acid acceptor. Chemical stress relaxation was the method most extensively used to determine the network changes taking place in the heat-aged fluororubber. Swelling, gel permeation chromatography (gpc), and infrared (ir) spectroscopy were also used to obtain additional information.
Effect of Carbon Black on Hysteresis of Rubber Vulcanizates: Equivalence of Surface Area and Loading
Authors: Caruthers J. M. , Cohen R. E. , Medalia A. I. 
Published: February 2011

Abstract
We have developed an empirical correlation between the loss tangent (tan δ) and the product of the volume fraction (ϕ) of carbon black in the composite and the total filler-polymer interfacial area per unit volume of composite (ψ). This correlation was applied to vulcanizates based on SBR-1500, SBR-1712, and NR with various compounding procedures and under different deformation conditions, including forced vibration nonresonant dynamic test machines, and the Goodyear-Healey pendulum rebound. The functional form of the correlation was qualitatively similar in all instances ; however, quantitative aspects of the correlation are dependent upon the particular experimental conditions. Tan δ is a weak function of the deformation amplitude over the region of practical interest. This is in contrast to hysteretic energy loss, which is proportional to the square of the amplitude. The validity of the correlation over wide ranges of amplitude, temperature, and frequency indicates that the viscoelastic relaxation or loss processes are similar over the range of conditions studied. Since the combined parameter, ϕψ, is proportional to ϕ2 multiplied by the specific surface area of the carbon black, this relation implies an equivalence between surface area and loading, with regard to tan 5. It has previously been shown that the elastic modulus depends on structure and loading. Thus, the dynamic properties, including hysteresis under various conditions, can be predicted from the carbon black properties, and compounds can be designed for desired dynamic properties by independent adjustment of loading, structure and surface area.
Conversion of Scrap Tires by Pyrolysis in Molten Salts
Authors: Larsen J. W. , Chang B. 
Published: February 2011

Abstract
Thermal decomposition in molten salts shows some promise as a method for recovering useful materials from scrap tires. Obviously, much technical development and engineering work needs to be done to evaluate that process. Applications of these techniques to other polymers is possible and is under study.
Silicone Rubber—A Perspective
Authors: Warrick E. L. 
Published: February 2011

Abstract
Silicone rubber began as a polydimethylsiloxane elastomer vulcanized by benzoyl peroxide. Today, 33 years after its discovery, silicone rubber is a line of products of widely different compositions and vulcanized by many different systems. Our knowledge of the rubber is far better than it was but it is by no means complete. Applications are many, but in general, they are in vital areas where extreme environmental conditions will not permit the use of any other material. Service life cost is usually lower than for other rubbers, despite higher initial cost. Uses in surgery fulfill a unique role in saving lives or improving the quality of life for many. Dr. R. R. McGregor said of the field of silicones, in general, “What had been started as a search for further knowledge proved to be the groundwork for technological advances that have proved helpful to industry, and in so doing, have contributed to improving our standard of living”. What he said of silicones as a whole, certainly applies to silicone rubber, and I have been happy to have contributed to the knowledge of silicone rubber and to have been a part of these advances which, in addition, contribute to our physical wellbeing by their use in the human body. These remarks are not in any way an epitaph for silicone rubber, but rather, they are the opening words in a book of growing usefulness for silicone rubber for us all. The adventure has just begun.
Copolymerization of Isobutene and Isoprene at “High” Temperature with Syncatalyst Systems Based on Aluminum Organic Compounds
Authors: Cesca S. , Bruzzone M. , Priola A. , Ferraris G. , Giusti P. 
Published: February 2011

Abstract
New catalyst systems based on alkylaluminum derivatives and halogen or interhalogen compounds were found highly efficient in the synthesis of high-molecular-weight IIR at temperatures above − 50°C. The reaction mechanism was studied in detail for the system Et2AlCl + Cl2. The reactions occurring between chlorine, isobutene, Et2AlCl, and the solvent (CH3Cl) were elucidated and studied under various experimental conditions (e.g. presence or absence of light, simultaneous presence of the copolymerization system components, temperature, type of halogen, use of model compound of isobutene). It was concluded that halogenium ions, i.e. Cl+, Br+, or I+, are the initiating species. Kinetic and conductometric investigations showed that scarcely dissociated ion pairs, e.g. Cl+[Et2AlCl2]−, were formed in the absence of monomer; but in the presence of isobutene, a noticeable increase of the electrical conductivity and rapid polymerization occurred. The maximum polymerization rate was first order with respect to the concentrations of monomer, Cl2, and Et2AlCl. In the homopolymerization of isobutene, transfer to monomer and termination reactions were negligible. The MW of IIR was found to be mainly dependent on the concentrations of the catalyst components, on isoprene concentration, and on temperature. The reactivity ratio of isobutene with isoprene was found to be r1=2.5±0.5 at −35°C, while the activation energies relative to MW were −5.8 ± 0.4, kcal/mol for polyisobutene, and −5.7 ± 0.7 and − 4.3 ± 0.5 kcal/mol for IIR containing, respectively, 1.3 and 1.9 mol% of isoprene. The evaluation of some physicochemical and technological properties of typical IIR produced with the system Et2AlCl + Cl2, indicated that isoprene is randomly distributed along the chains and that the MWD is monomodal, while the glass transition temperature, tensile properties, mechanical-dynamic spectra, and kinetics of vulcanization are very similar to those of commercial IIR. Very preliminary data, referring to several classes of new catalyst systems yielding IIR having good properties, were also obtained. The syncatalyst systems here described can work in a homogeneous phase consisting of an aliphatic hydrocarbon besides methyl chloride, still giving IIR with high MW. Therefore, a completely homogeneous process can be envisioned for the synthesis of IIR at −50°C thus avoiding a great part of the fouling problems of the slurry process. The economic advantage of using “high” temperatures of polymerization is briefly discussed in terms of energy savings.