bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Accelerators on EPDM Vulcanizate Structure
Authors: Baldwin F. P. 
Published: February 2011

Abstract
This study of vulcanization has revealed that in low unsaturation EPDM elastomers prepared with ethylidenenorbornene— 1. Stearic acid can be a useful additive for vulcanization. Increasing concentration in the range 0-4 phr leads to faster curing and reduced polysulfidic crosslink concentration at a given crosslink density. 2. Low sulfur and low sulfur/accelerator ratio and/or prolonged curing times are required to generate vulcanizates containing low percentages of polysulfidic crosslinks. 3. At identical crosslink densities, high temperature cures display a lower level of polysulfidic crosslinks than low temperature cures. However, olefin utilization in crosslinking is generally better with low temperature curing. 4. At high sulfur levels, variations in crosslink type distribution resulting from accelerator changes tend to disappear. 5. Mixed acceleration—a dialkylthiocarbamic acid derivative and an accelerator having the benzothiazolylthio radical—appear best suited for the combination of maximizing cure rate and producing stable (lower sulfur rank) crosslinks. Taken together with other information, the results of this study lead to the suggestion that: 6. The stability of the basic accelerator nucleus is influential both on cure rate and on the ability to generate stable crosslinks. 7. The exact structure and concentration of the olefinic moieties present in the polymer have at least as much bearing on the detailed outcome of the vulcanization process as do changes in accelerator. 8. A useful accelerator for these rubbers resulting in the production of vulcanizates containing a high concentration of low rank sulfur crosslink might derive from a MBT type synthesis based on a properly ringalkylated aniline. 9. Some effort devoted to the study of chemicals which may not accelerate crosslinking but could participate in the crosslink shortening process would appear worthwhile.
The Effects of Modulus and Sulfur Concentrations on the Properties of SBR Vulcanizates
Authors: Cox W. L. 
Published: February 2011

Abstract
While it has long been recognized that the original and aged properties of a vulcanizate depend to a very large extent on the number and type of the chemical crosslinks present, the exact nature of this dependence is seldom reported. The present study was undertaken to investigate systematically within a set of sulfenamide-accelerated sulfur vulcanizates of SBR the relative importance of crosslink frequency and character. Since the moduli of rubber compounds differing only in curative concentrations furnish a convenient measure of the relative numbers of crosslinks present, this property was taken as one variable of an experimental design, with sulfur concentration as the other. Obviously, to achieve different moduli values at a given sulfur level, alterations in the accelerator concentration must be made, and any interpretation of data must take this fact into account.
Modulus of Natural Rubber Crosslinked by Dicumyl Peroxide. I. Experimental Observations
Authors: Wood L. A. , Bullman G. W. , Decker G. E. 
Published: February 2011

Abstract
Natural rubber mixed with varying amounts of dicumyl peroxide are crosslinked by heating 120 min at 149° C. The quantitative measure of cross- linking was taken as the amount fp of decomposed dicumyl peroxide, the product of p, the number of parts added per hundred of rubber and f the fraction decomposed during the time of cure. The shear creep modulus G was calculated from measurements of the indentation of a flat rubber sheet by a rigid sphere. The glass transition temperature Tg, was raised about 1.2° C for each part of decomposed dicumyl peroxide. Above (Tg+12) the modulustemperature relations were linear with a slope that increased with increasing crosslinking. The creep rate was negligible except near the glass transition and at low values of fp. Values of G, read from these plots at seven temperatures, were plotted as a function of fp. The linearity of the two plots permits the derivation of the general relation: G=S(fp+B)T+H(fp+B)+A where A, B, H, and S are constants. The lines representing G as a function of fp at each temperature all intersected near the point, fp=0.45 phr, G=2.70 Mdyn cm−2(0.270 MN  m−2). . The constants were evaluated as A=2.70 Mdyn cm−2,B=−0.45 phr, S=5.925×10−3 Mdyn cm−2(phr)−1 K−1 and H=0.0684(Mdyn cm−2) (phr)−1. This equation represented satisfactorily all the data obtained at temperatures from —50 to +100° C for values of fp from about 1 to 24 phr.
Basic Fundamentals of Extrusion and Mixing Theory
Authors: Boguslawski J. J. 
Published: February 2011

Abstract
The first mechanically driven extruders for rubber and rubber-like materials were developed by Francis Shaw in 1879 in England and John Royle in 1880 in the U. S. A. For nearly 60 years the design of extruder screws remained as an art. With rapidly expanding plastic markets and rapidly rising labor and processing machinery costs, the extruder users and builders realized that only close co-ordination and cooperation among scientists, engineers, and process workers could develop an extruder which would be the most universal and economical tool in polymer processing. Between 1946 and 1953 most of the modern extrusion theory was developed. It has been proven that extrusion theory, when combined with test data and practical experience, is an extremely useful tool. Due to an abundance of empirical data and fundamental theory, extrusion technology has now grown far beyond the level of a mechanical art. At least part of the process can be described by mathematical relationships through the application of rheology, thermodynamics, and fluid dynamics theory. Important advances have been made in process control as well as in increasing output. It is significant that the technology of the rubber extruder, the parent of the plastic extruder, can even now benefit directly from these developments. The transition from hot feeding to use of cold rubber particles can be mentioned as an example.
Modern Extrusion Equipment
Authors: Smith D. H. , Christy R. L. 
Published: February 2011

Abstract
Rubber extruders have been developed and refined to a degree where it is not always obvious which is best for a given application. This paper will cover the latest refinements in the hot feed, cold feed, and vented cold feed type single screw extruders and compare their performance, limitations, and capabilities. Shaping the compound into a more useable form has traditionally been the primary extruder function. However, today cold feed extruders are being used in various environments where shaping is secondary to their ability to plasticate efficiently and uniformly on a continuous basis. An example of this is warm-up for calendar and injection molding equipment.
Recent Advances in the Chemistry of Polyurethanes
Authors: Frisch K. C. 
Published: February 2011

Abstract
Major emphasis in recent years has been placed upon efforts to develop aliphatic isocyanates to impart light stability and improved stability toward hydrolysis. Another major area of research activity were new methods for the generation of isocyanates. Aliphatic isocyanates. The first commercial aliphatic diisocyanate used was 1,6—hexamethylene diisocyanate (HDI), OCN (CH2)6NCO, a colorless liquid, boiling at 127° C at 10 mm Hg; it is less reactive than either tolylene diisocyanate (TDI) or 4,4′-diisocyanatodiphenylmethane (MDI). However, in the presence of certain metal catalysts, such as tin, lead, bismuth, zinc, iron, cobalt, etc., the activity of the aliphatic isocyanate groups is equal to or greater than that of the isocyanate groups in TDI. The use of hexamethylene diisocyanate (HDI) leads to urethane polymers having better resistance to discoloration, hydrolysis, and heat degradation as compared to TDI. Due to its high vapor pressure and toxicity, a higher molecular weight modification of HDI is often employed which is made by reaction of 3 moles of HDI with 1 mole of water:
Steel Cord Skim Compounds: The Achievement and Maintenance of Maximum Adhesion
Authors: Ayerst R. C. , Rodger E. R. 
Published: February 2011

Abstract
The adhesion of rubber to brassed steel cord has been assessed by a static pull out test which avoids many of the problems associated with current H tests. The test is simple in operation and with a uniform stress distribution gives results which are independent of modulus, with a high degree of reproducibility. The effect of a range of compounding variables on adhesion has been examined. Curing systems and polymer type were identified as having the greatest influence. High unaged adhesion was achieved with a curing system based on 2-(Morpholinothio)benzothiazole in 100 NR or NR/BR blends.Factory processing can reduce adhesion in the final vulcanizate and the addition of N-cyclohexylthiophthalimide will prevent this. Overcure and oxidative aging also reduce adhesion. Systems based on low sulfur levels with 2(Morpholinothio)benzothiazole and N,N-dithiodimorpholine confer high resistance in NR and NR/BR blends. The antidegradant combination of N(l,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymerized 2,2,4-trimethyl-l-2-dihydroquinoline gave further improvements in oxidative aging resistance without reducing unaged adhesion.
Transition from Linear to Nonlinear Viscoelastic Behavior. III. Linearity below and above TG
Authors: Yannas I. V. 
Published: February 2011

Abstract
This work correlates diverse data from the literature in an effort to mark the stress and strain limits of linear viscoelasticity theory below and above Tg for amorphous polymers. The data on limits of linear behavior are based on deviation of 3 per cent from theory and extend from Tg−150° C to Tg+150° C. It is shown that, whereas the stress limit of linear behavior drops as Tg is crossed from below, the strain limit increases from ca. 1 to ca. 100 per cent over the same temperature region.
Application of Gas-Liquid Chromatography to the Thermodynamics of Polymer Solutions
Authors: Patterson D. , Tewari Y. B. , Schreiber H. P. , Guillet J. E. 
Published: February 2011

Abstract
It has been well established that gas—liquid chromatography (glc) can give accurate thermodynamic data on binary solutions where the components differ considerably in volatility or molecular weight. The substance of lower molecular weight (component 1) is injected into the moving gas phase and dissolves at effectively infinite dilution in the stationary liquid phase. This is formed by the higher molecular weight material, for example, squalane, biphenyl, dinonyl phthalate, glycerol, or the higher n-alkanes such as C16, C24, C36, etc. The convenience of the technique is such that activity coefficient data have already been obtained for hundreds of systems. In contrast, activity data are available for far fewer high polymer systems, in part certainly because of the need to use the laborious vapor sorption technique. While that technique gives activity data as a function of concentration, it would still be desirable to have data at infinite dilution for a variety of systems in order to test contemporary theories of polymer solution thermodynamics. Recently Guillet and coworkers have applied the glc technique to systems in which the stationary phase is a high polymer. (J. E. Guillet and coworkers refer to the gas-phase component as the molecular “probe”. This avoids the glc teminology in which that component is the solute and the stationary-phase polymer would be the solvent. This terminology is confusing to polymer chemists used to solutions where the polymer is the solute, being present at low, rather than high, concentrations.) Their primary interest has been to demonstrate the versatility of the technique in determining first- and second-order phase transitions, degrees of crystallinity, and other physical characteristics of the polymer, while the present communication considers the determination of thermodynamic quantities. It has been prompted by comments from several workers who have noted the difficulty of applying the usual thermodynamic equations of glc which yield γ1∞, the activity coefficient of component 1 at infinite dilution [Equations (5) and (6)]. The equations require an exact value of the molecular weight of component 2, making difficult their use for polymer systems. Our main objective is to resolve this problem. However, we also wish to stress the utility of the technique in providing data with which to test contemporary theories of polymer solution thermodynamics. We therefore comment on equations which directly relate experimental glc data to the interaction parameter, χ, of polymer solution thermodynamics.
Creativity in Rubber Industry Research. Charles Goodyear Medal Address—1971
Authors: Osterhof H. Judson 
Published: February 2011

Abstract
Over the span of 36 years in rubber research and development, I was involved in a wide range of problems, some of which ended in frustration, others fortunately in success. Overall, during this entire period, I've had a whale of a good time. During these years nothing has provided me more satisfaction than working with creative people. And since this phenomenon of creativity is so important and yet so little understood, I thought I'd see whether from my own experience I could throw a little light on it today. My main qualification is that I have for years been interested in creativity, what it is, how it manifests itself, the type of people who exhibit it, and how they may be encouraged toward greater efficiency. Successful creativity, in general, involves conceiving new ideas and following them through to where they become potentially useful. It does not only mean the synthesis of a new chemical, but more broadly, the achieving of any new, not previously recognized, result. This might involve merely bringing together two well-known mechanical devices never before associated. For example, the electric blanket invented by Kearsley of General Electric: blankets and electric heating wire were well known, separately, but it took Kearsley's imagination to bring them together into a brand-new useful product. Many instances of creativity sart with Observation, the creative person being alert for new combinations and phenomena, being led on by his scientific Curiosity, aroused by his Imagination and Enthusiasm, and drawing upon his Memory, since creative thinking is frequenly no more than bringing together factors not hitherto associated. Among the requisite personal characteristics for creativity arc a prepared mind, a large range of skills and technical know-how, a certain mechanical ingenuity, and a favorable environment. The creative mind must, of course, have imagination, as well as enthusiam. Its results may range from discovering a whole new world of knowledge to merely inventing an easier way of doing an old job. To enhance the creativity of research personnel, management cannot impose a rigid application of job specialization and supervisory control, but must create a climate with such necessary freedom and flexibiliy as to be conducive to invention. Technological innovations can result from following various creativity routes which, for convenience here, I have divided into seven categories. For a clearer picture of how creativity manifests itself, let us examine some appropriate examples, based on projects with which I had direct personal contact. Of these examples, some are important, others relatively minor, the basis of selection being primarily suitability for illustrating various facets of creativity. These might be considered case histories, as it were, of creativity.
Thermal Stability of the Carbon-Carbon Crosslink in Polymer Networks
Authors: Shaw Montgomery T. , Tobolsky Arthur V. 
Published: February 2011

Abstract
The thermal stability of carbon-carbon crosslinkages in elastomeric systems was studied by comparing the vacuum chemical stress relaxation of samples with different concentrations of these crosslinkages. The systems studied included silicone rubber, crosslinked polyethylenes, and Dexsil-201 rubber. Arrhenius activation energies of about 55 kcal/mol were found for the scission of these crosslinkages in the temperature range 300—350°. Crosslinkages added to a sample by additional curing were found to be, in general, more stable than those first formed. A more detailed analysis of the cleavage reaction was performed on peroxide-cured Dexsil-201 elastomer—made possible because the main chains of this material are stable at the temperatures used. Two species of crosslinks were distinguishable: one having the same stability as the carbon-carbon crosslinkage in silicone rubber, another being ten times as stable and probably devoid of normal carbon-carbon bonds.
Radiation-Convertible Polymers from Norbornenyl Derivatives. Crosslinking with Ionizing Radiation
Authors: Colomb H. O. , Trecker D. J. , Osterholtz F. D. 
Published: February 2011

Abstract
Vinyl polymers with pendant norbornenyl (bicyclo [2.2.1]heptenyl) groups crosslink rapidly on exposure to ionizing radiation. Analysis (according to Charlesby-Pinner theory) of extraction data from an ethylene—vinyl acetate copolymer and the corresponding ethylene—vinyl norbornenecarboxylate copolymer shows that the unsaturated polymer crosslinks by a chain reaction. At low doses, the kinetic chain length is about 4. Pendant norbornenyl groups accelerate crosslinking of a vinyl alcohol—vinyl acetate—vinyl chloride copolymer and convert poly(vinyl alcohols) and cellulose acetate from degrading to crosslinking polymers. A novel application of the Charlesby-Pinner plot strongly suggests linear dependence on the extent of crosslinking on the norbornenyl group concentration in a series of modified poly(vinyl alcohols). The greater effectiveness of pendant norbornenyl groups, compared to cyclohexenyl groups demonstrates the importance of the reactivity of the double bond.
Ethylene Propylene Vinylcyclohexene Terpolymers
Authors: Caywood S. W. 
Published: February 2011

Abstract
4-Vinylcyclohexene reacts via the vinyl group with ethylene and propylene in a Ziegler-type polymerization to form an elastomeric terpolymer. The reactivity of vinylcyclohexene in this polymerization is lower than that of 1,4-hexadiene and norbornene by a factor of about 7 and 70, respectively. Ethylene propylene vinylcyclohexene terpolymers respond poorly to typical EPDM sulfur vulcanization systems but react well with a catalyzed resin system or a peroxide recipe.
Vulcanizate Properties from a New Perfluoroelastomer
Authors: Barney A. L. , Kalb G. H. , Khan A. A. 
Published: February 2011

Abstract
Vulcanizate properties of a new high performance elastomer, a terpolymer of tetrafluoroethylene, perfluoro (methyl vinyl ether) and a small amount of a third perfluoromonomer containing an active cure site, are described. The material may be compounded with various reinforcing agents (black exhibits the greatest reinforcing power) or as a gum stock. Perfluorinated oils such as Krytox § may be added as plasticizers. The vulcanizates show outstanding chemical resistance to many alkalies, acids, oxidizing agents and reducing agents; outstanding resistance to air oxidation at temperatures in the 400 ° – 550 ° F range; low volume swell in many organic fluids such as ketones, esters, nitriles, hydrocarbons and halogenated solvents, including the proprietary hydraulic fluids and jet fuels; and good high temperature (to 550 ° F) compression set.
Stress-Strain Behavior of Natural Rubber Vulcanized in the Swollen State
Authors: Price Colin , Allen G. , de Candia F. , Kirkham M. C. , Subramaniam A. 
Published: February 2011

Abstract
Samples of natural rubber were vulcanized in the presence of n-decane, decalin and o-chlorobenzene. The diluents were then removed, and the force-extension characteristics of the samples studied over the range 1.1&lt;α&lt;2.0. The elastic behavior of the solution-vulcanized elastomers appear to be in much closer agreement with the statistical theory of elasticity than is the case for vulcanizates prepared in the dry state.
Liquid Rubbers—General Rubber Products Technology
Authors: Pyne J. R. 
Published: February 2011

Abstract
Mixing and processing methods used in the rubber industry have been designed to use the only form of raw rubber hitherto available—that of a high molecular weight solid. But rubber in high molecular weight form is essential only in the finished product; in principle, similar final properties could be obtained from a low molecular weight raw material provided this could be chain extended before or during the final shaping and vulcanizing operation. This approach has been employed for some time in the rather specialized field of castable polyurethane rubber manufacture. Its exploitation for more general rubber manufacture has become more than just a theoretical possibility with the recent availability of “liquid rubbers” whose molecules have reactive end groups. Those available at present may well prove not fully acceptable, either economically or technically, but it is most unlikely that they represent the best that can be achieved. Material developments will be encouraged if means have been worked out for exploiting liquid rubbers' potential advantages (such as the ability to be processed on lighter and less powerful equipment), and the shortcomings of existing examples have been identified. These considerations led RAPRA to start a processing and compounding study—a decision which seems further justified by the very recent American announcements of development work on a tire manufacturing process using liquid rubber, and of full commerical scale production of several hydroxyl terminated liquid butadiene polymers. This report summarizes the study to date.
Structural Characterization of Vulcanizates. XI. Network-Bound Accelerator Residues
Authors: Campbell D. S. 
Published: February 2011

Abstract
Radiotracer techniques have been used to determine amounts of accelerator which become bound to the vulcanizate networks during the vulcanization of NR with sulfur and CBS, Three different vulcanization systems have been studied, having different proportions of accelerator to sulfur. The vulcanizates have also been characterized in terms of the numbers and types of chemical crosslinks present and the results of the bound accelerator analyses have been considered in relation to the crosslink levels and distribution.
The Effect of Road Surface Texture on Tire Wear
Authors: Lowne R. W. 
Published: February 2011

Abstract
(1) This experimental work has shown that there is a large variation in the degree of tire wear on different surfaces, the wear on the rough, harsh surface being approximately three times as severe as that on the rough polished surface. (2) Measurement of weight loss by the method described provides a sensitive measurement of tire wear. (3) Qualitative analysis has shown that it is the harshness of the surface which is of major importance in tire wear, with surface roughness as a slightly modifying factor. (4) Quantitative analysis of various parameters indicating surface characteristics has shown that the shape of the asperity tips and the low-speed, wet coefficient of friction are major factors. These can be used to predict wear to a high degree of significance within the range of values covered by these measurements, although a large sample of surfaces would be desirable to check this relationship further. (5) A decrease in the severity of wear of six times involving a drop in speed from 50 km/h to 25 km/h has not altered the relative wear ratings of the three surfaces which have been compared and it seems reasonable to assume that the relative wear rates, although not the absolute values, would be the same in normal conditions of use. Consequently, the increased use of rough road surfaces is not expected materially to affect tire wear. (6) Significant increase in tire life from a wear standpoint can be expected from the use of radial ply tires instead of cross ply tires.