bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Structure of Rubber Networks with Multifunctional Junctions
Authors: Pearson D. S. , Graessley W. W. 
Published: February 2011

Abstract
A number of statistical relationships have been derived for calculating the structure of rubber networks with multifunctional junctions. Some of these quantities appear as parameters in the molecular theory of elastic energy in phantom networks. Others relate to Langley's trapping factor for the entanglement contribution to the modulus, to the maximum extensibility, and to the viscoelastic properties of networks.
The Vulcanization of Styrene-Butadiene Rubber with 2-Pentadecyl-Benzoquinone Dioxime
Authors: Ghatge N. D. , Maldar N. N. 
Published: February 2011

Abstract
The authors propose a new active vulcanizing agent 2-pentadecylbenzo-quinone dioxime, derivable from the indigenous raw material, cashewnutshell liquid. This vulcanizing agent, when oxidized by red lead, gives styrene-butadiene vulcanizates of improved tensile strength and elongation at break, compared to vulcanizates cured by p-benzoquinone dioxime, 2-methylbenzo-quinone dioxime or standard sulfur curing systems. The new vulcanizates have much greater resistance to heat aging than the corresponding sulfur vulcanisates.
Effects of Compounding Variations on the Properties of Guayule Rubber
Authors: Porter L. S. , Stephens H. L. 
Published: February 2011

Abstract
The vulcanization characteristics of guayule and NR respond similarly to compound modifications: the major difference being that the addition of N219 carbon black affects GR more than NR; the gum stock scorch time is higher for GR, but the black stock scorch times are similar (Figures 7 and 8). The GR and NR physical properties respond similarly to compound modifications in all cases. The free rubber static and dynamic response of GR and NR is similar with compound modifications. However, the GR response to dynamic excitations is different than the NR response, as seen by the significantly higher dynamic rates of GR when the static compressions are nearly identical (Figures 15 through 18). The bushing assembly data point out the same characteristics noted for the free rubber. The GR bushing fatigue life appears to be as good as NR and is superior to SN.
Ethylene Propylene Rubber and Crosslinked Polyethylene as Insulations for 90°C Rated Medium Voltage Cables
Authors: Blodgett R. B. 
Published: February 2011

Abstract
Amorphous ethylene propylene rubber insulated power cables are expected to be more stable under high temperature conditions than crystalline crosslinked polyethylene insulated cables. The properties of amorphous EP rubbers are little affected by temperature from −30 to 150°C; those of crystalline XLPE fall off as temperature exceeds the melting point (around 100°C) of the crystalline regions. Probably reinforced amorphous EP rubber insulated cables are expected to be more stable in wet locations than unfilled XLPE insulated cables. They do not fail by the formation of water trees as the primary mechanism, since the bonds between filler and polymer are stronger than the forces responsible for water trees forming in XLPE cables in service. The reinforcing effect of fillers in EP rubber makes questionable any extrapolation from high stress treeing studies of unreinforced PE, XLPE, or EP polymers. For the longest possible life in wet locations insulation should be protected by a water impermeable metallic sheath, which must be protected against corrosion, mechanical damage, fatigue cracks, etc. Any insulation will eventually fail on continued exposure to water and electrical stress.
Modifications of Low Functionality Elastomers
Authors: Baldwin F. P. 
Published: February 2011

Abstract
Last year at the Boston meeting, Herman Schroeder in introducing a session stated, “Research is cheap, it is development which is expensive”. I certainly concur and I would add that it is the dream of all industrial researchers to see the results of their research reach the marketplace. There is no secret to the transition from laboratory to commercial development. What is required is: (1) Personal zeal, a thesis, and a cooperative atmosphere in the laboratory stage. This characterized the people in the Elastomers Group at Exxon. (2) Some good engineers who can devise an economical process for the product. (3) At least one knowledgeable and aggressive product champion in the market development stage. (4) Reliable cooperation and feedback from potential users. (5) A current or impending need in the marketplace. (6) The availability of some risk capital and business people who have the courage and confidence to use it as such. (7) A technical service-research organization that can carry the product through the rough spots encountered in its introduction and thereafter. The researcher must accept the fact that not too many ideas are likely to result in commercial success in any particular milieu, because of these many conditions which must be met in orderly and timely fashion. I have mentioned many names in this talk. Without difficulty and with ample justification, I could mention many more and herewith wish to acknowledge all those who at one time or another contributed to making mine an interesting, exciting and satisfying career in industrial research. I appreciate having had this opportunity to talk to you and am genuinely thrilled, as is my family, that you have accorded me this honor. Beyond that, though times are a bit troubled, be assured that the rubber industry is neither dead nor dying. There is much research to be done and many new products and concepts to be developed. Keep at it, don't get discouraged and best of luck to you all. Thank you.
High Temperature Vulcanization of Elastomers
Authors: Bhowmick A. K. , Mukhopadhyay R. , De S. K. 
Published: February 2011

Abstract
Vulcanization is a process which decreases the plastic properties of rubber while maintaining or improving the elastic properties. The term vulcanization has been applied in the past mainly to the reaction of rubber with sulfur, but now is generally used for the process which results in changes in properties, by sulfur or some other agent. There are four principal changes brought about by vulcanization: (1) rubber is changed from essentially a plastic to a non-plastic material; (2) rubber is changed from a material soluble in a number of solvents to one which is insoluble; (3) rubber is changed to a material with greatly improved physical properties; (4) these properties of vulcanized rubber are maintained over a much wider range of temperature than those of unvulcanized rubber. What is meant by high vulcanizing temperature? There is no unique answer. About 160°C can be taken conveniently as the lower limit; this temperature has been suggested as the highest suitable for some normally compounded sulfur curing rubbers. The upper limit may be 220°C, above which the polymer may begin to degrade. The range in practice extends up to about 250°C in fluid beds and salt baths. Practical vulcanization processes apply heat to the outside of the article being cured and rely on the conduction of heat to the inside. Since no drastic change can be made in the thermal conductivity of practical rubber compounds by compounding modifications, higher temperature is a common method of achieving faster vulcanization. Higher curing temperatures are used in the newer curing or molding processes such as injection molding, the liquid curing medium (LCM) process, and microwave curing.
Scale-Up of Short Fiber Composite Mixing
Authors: Shen K. S. , Rains R. K. 
Published: February 2011

Abstract
A dimensionless parameter, NRS, based on the probable number of passes through the shear zone for an ingredient to be dispersed, was developed for scale-up of mixing of short fiber composite in an internal mixer. A single curve was obtained for the dispersion-NRS relationship of three widely different compounds in five internal mixers of various sizes. The parameter is an improvement over previously reported scale-up parameters, because the temperature profile does not have to be matched for different size mixers. The dimensionless dispersion number concept can be extended to dispersion of other ingredients, as long as the shear stress generated at the mixing temperature is higher than the interaggregate cohesive force of the particles. Based on this parameter, NRS, the dispersion of short fibers can be predicted from one size of internal mixer to another size mixer. It is also possible to predict the mixing time required for a given dispersion rating.
Mechanical Chain-Scission in Rubber Vulcanizate at Low Temperatures
Authors: Kusano T. , Kobayashl K. , Murakami K. 
Published: February 2011

Abstract
When vulcanized natural rubbers are forced to extend in the glassy state, free radicals are produced by the scission of the primary chain. The amount of the free radicals increases with the strain. The tensile yield strain decreases with the decrease of the molecular chain length between crosslinks. This behavior is explainable on the basis of the limited chain extensibility. The extended chains are broken with further increases of the strain. The mechanically produced free radicals are quite stable below about −40°C. The crosslink density of the chain-ruptured material increases about 2∼3×10−5 mol/cm3. This fact shows that the free radicals are consumed not only by recombination but by the intermolecular reaction. In both sulfur and DCP vulcanizates, the network chains rather than the crosslinks are broken by stretching. In an air stream, some free radicals react with oxygen and others form crosslinks.
Polyurea Dispersions for RIM Applications
Authors: Phillips B. A. , Taylor R. P. 
Published: February 2011

Abstract
PHD polyols have been demonstrated to be more effective agents for increasing the flexural modulus of high modulus RIM elastomers than normal poly(oxyethylene) polyols or polymer polyols. As expected for higher modulus RIM materials, tensile strength also increases, and impact strength and elongation decrease. The use of PHD polyols also effectively increases flexural modulus without the excessive brittleness or reactivity that would result from the use of higher concentrations of glycol or amine chain extenders, polyfunctional isocyanates or polyol crosslinking agents.
Model Compound Vulcanization—Part II. Comparison of Accelerators
Authors: Lautenschlaeger F. K. , Zeeman P. 
Published: February 2011

Abstract
The efficiency of each of 20 accelerators to convert sulfur into sulfidic products has been evaluated by Model Compound Vulcanization. The sulfidic products can be isolated and identified by gas-liquid chromatography. The sulfidic products can be separated into groups of mono-, di- and trisulfides, with several isomeric products within each group. This paper has reported on the analysis of such isomeric products which correspond to different types of sulfur crosslinks in natural rubber vulcanizates. The analysis of monosulfidic product yields and of the isomer distribution within the monosulfide group is sufficient to characterize an accelerator.
Model Compound Vulcanization—Part IV. Comparative Assessment of Sulfenamide and Triazine Accelerators
Authors: Lautenschlaeger F. K. , Edwards K. , Kirkham M. C. 
Published: February 2011

Abstract
The application of model compound vulcanization (MCV) to the rating of the relative efficiency of CBS (N-Cyclohexylbenzothiazole-2-sulfenamide) and an experimental triazine-based accelerator is demonstrated. The sulfur to accelerator ratios were established at which both accelerators lead to the same total sulfidic product yield. At these ratios, selected initial properties of natural rubber vulcanizates and their reversion resistance are similar. Hence, the increased reversion resistance of triazine-accelerated natural rubber vulcanizates is essentially due to their greater efficiency in converting sulfur into sulfidic crosslinks. A higher level of the less efficient CBS leads to similar results. This analysis shows that MCV simplifies the evaluation of accelerators.
Dithiodimorpholine-Based Accelerator System in Tire Tread Compound for High-Temperature Vulcanization
Authors: Bhowmick A. K. , De S. K. 
Published: February 2011

Abstract
A tire tread compound suitable for high-temperature vulcanization has been designed. Of the various mixes studied, the one containing dithiodimorpholine (1 phr), CBS (2 phr) and sulfur (0.5 phr) was found to be most suitable for high temperature vulcanization of natural rubber. The network structures of the vulcanizates have been determined, and the technical properties of the new tire tread compound have been compared with those of a conventional compound. It has been found that a DTDM-based compound is superior in technical properties, reversion resistance and ageing resistance. The polymer-filler attachment was found to be higher DTDM-based compounds than for conventional ones.
Control of Alfin Rubber Molecular Weight
Authors: Hansley V. L. , Greenberg H. 
Published: February 2011

Abstract
Control of molecular weight of alfin catalyzed diene polymers has been demonstrated for polymers of butadiene, isoprene, styrene, piperylene and combinations of these. The 1,4-dihydro derivatives of benzene and naphthalene are effective molecular weight moderators. The known microstructure of alfin polymers remains unchanged with the use of these agents. Molecular weight controlled alfin gums process readily on standard rubber machinery. Oil extenders or softeners, although not necessary, are easily incorporated. The feasibility of continuous processing has been demonstrated for the production of catalyst, moderators and polymers on pilot plant scale. A wide series of polymers and copolymers at predetermined molecular weights and compositions have been produced in the same pilot plant. Alfin polybutadiene with limited amounts of styrene is essentially a solution type SBR. Alfin copolymers with styrene and/or isoprene have undergone preliminary road tests in tires. Wear and heat build-up data indicate performance to be intermediate between SBR and polybutadiene.
Measurements of Friction of Elastomers by The Skid Resistance Tester
Authors: Bassi A. C. 
Published: February 2011

Abstract
A skid resistance tester was used as a laboratory instrument for testing dynamic friction coefficients between rubber vulcanizates and standard wet surfaces. Test conditions required to obtain satisfactory experimental results, are examined. The influence on skid measurements of the type of elastomer and amount of carbon black are considered. Skid resistance is correlated with hysteretic properties of the material; some results on the influence of surface phenomena, like water-rubber adherence are reported. Other measurements performed on oiled instead of water wet surfaces and on smooth ice are described.
Volatility of Antioxidants and Antiozonants II. Effect on Rubber Testing
Authors: Spacht R. B. , Hollingshead W. S. , Bullard H. L. , Wills D. C. 
Published: February 2011

Abstract
In the first paper of this series data were presented on the volatility and vapor pressure of eight antioxidants. The present work attempts to show how volatility-affects the performance of an antioxidant, particularly in accelerated aging tests. The usual accelerated tests are of two types: those using closed systems such as the air bomb, the oxygen bomb, and oxygen absorption, and those using open systems such as air oven aging and creep.
Vulcanization of Elastomers. 39. Vulcanization of Natural and Synthetic Rubbers by Sulfur and Sulfenamides. II
Authors: Scheele W. , Kerrutt G. 
Published: February 2011

Abstract
The dependence of the kinetics of vulcanization of natural rubber by sulfur in presence of N-cyclohexyl-benzothiazolylsulfenamide (CHBS) on temperature and for varied molar ratios of accelerator and sulfur was more exactly investigated. 1. Although the vulcanization of natural rubber accelerated with N-cyclohexyl-benzothiazolylsulfenamide with conventional experimental conditions is characterized by very long induction times, nevertheless—as also for other accelerated vulcanization reactions—sulfur decrease follows a time law with nt&lt;1 and the activation energy, as in other cases, is calculated to be 29 kcal/mole. 2. The value nt=0.6 is found for the exponent of the time law, independent of temperature and concentration of reactants. 3. The concentration dependence of the rate of sulfur decrease under conditions of constant sulfur content and increasing sulfenamide concentration is found to be consistent with catalysis by an intermediate compound. 4. The actual accelerator may be essentially cyclohexylammonium-benzothiazoylmercaptide. 5. The temperature and concentration dependence of the induction periods for sulfur decrease and crosslinking were investigated. The course of crosslinking with reaction time, which is characterized by strong reversion, is discussed.
Vulcanization. Part VII. Kinetics of Sulfur Vulcanization of Natural Rubber in Presence of Delayed-Action Accelerators
Authors: Coran A. Y. 
Published: February 2011

Abstract
The scheme and treatment of the kinetics of scorch-delay vulcanization proposed in a previous paper were applied to natural rubber sulfur vulcanization accelerated by 2,2′-thiobisbenzothiazole (MBTS), 2-(N-cyclohexyl)benzothizaolesulfenamide (CBS), 2-(N-morpholinothio)benzothiazole (MOR), or 2-(N,N-diisopropyl)benzothiazolesulfenamide (DPBS). According to the scheme (see PDF for diagram) where the subscript x = a positive integer. The specific rates k1 and k2 and the ratiok4/k3′ were related to starting concentrations of accelerator, sulfur, and stearic acid. In general, an increase in stearic acid concentration or a decrease in accelerator concentration induces an increase in k1 or k4/k3′ but a decrease in k2. An exception to this is that, when the highly hindered sulfenamide DPBS is used as the accelerator, k1 does not change with changes in starting concentrations. It is interesting that k2 does not respond appreciably to changes in sulfur concentration when sulfenamides are used, unless the sulfur concentrations are extremely low. In contrast to this, k2 increases linearly with the square root of the sulfur concentration when MBTS is used. The changes in rates which occur with changes in the starting concentrations were attributed to the formation of chelates between zinc ion (brought into solution by stearic acid) and accelerator, intermediate reaction products, or crosslink precursors. The differences noted between the rates obtained with the three sulfenamides were attributed to differences in steric hindrance and stability.
Compounding Styrene-Butadiene Rubber with Shellac. II
Authors: Saxena K. K. , Banerjee S. 
Published: February 2011

Abstract
This study demonstrates that both shellac and its ester improve considerably most of the mechanical properties of SBR. Shellac-ester functions more favorably in this regard. Both these materials can be used as a reinforcing filler for SBR especially if the end product is not intended to be used in service demanding severe abrasion.
Infrared Studies of the Rubber-Filler System. II. Identification of Rubbers Compounded with Fillers by Infrared Absorption Spectra
Authors: Suito E. , Arakawa M. 
Published: February 2011

Abstract
Infrared spectra of vulcanized rubbers compounded with fillers were studied on thin sections of samples made by a low temperature microtome technique. By this method, identification of fillers as well as rubbers is possible. The infrared absorption spectra of rubbers compounded with several types of fillers are described.
Peroxide Crosslinking of Ethylene-Propylene Rubber
Authors: Loan L. D. 
Published: February 2011

Abstract
The crosslinking of ethylene-propylene rubber by means of cumyl peroxide has been followed in detail. The overall crosslinking efficiency has been found to be about 0.4 crosslinks per peroxide molecule, and this result has been shown by stress relaxation and permanent set experiments to result from a mixture of both scission and crosslinking reactions. The results obtained with two different rubbers are consistent with the view that scission results from abstraction of a tertiary hydrogen atom while crosslinking arises from attack at a secondary hydrogen. Such a scheme allows a relative reactivity of tertiary:secondary of 6:1 to be calculated. The action of sulfur in peroxide cures has been shown to be to introduce labile, presumably sulfur-containing, crosslinks. Such labile crosslinks explain the increased tensile strength of such vulcanizates. Allyl compounds are effective in increasing the crosslinking efficiency of the peroxide.
Light Scattering from Crystalline Superstructure in Stretched Natural Rubber
Authors: Yau W. , Stein Richard S. 
Published: February 2011

Abstract
The existence of fibrous structure in stretched crystalline elastomers has recently been reported by Walters. It has been suggested that this structure represents stress crystallinity. The low-angle light scattering from stretched, cured natural rubber has been under study in this laboratory, and it has been reported that the scattering pattern results from crystalline superstructure accompanying the stress-induced crystallization. This structure has a size of the order of microns and is undoubtedly related to the structure reported by Walters. Rubber samples studied were experimental sulfur-cured samples not containing any filler. Light-scattering studies were carried out by the laser photographic technique which has been described. It was found necessary to sandwich the elongated samples between microscope cover glasses using a silicone oil immersion fluid to prevent surface scattering from making an undue contribution. Scattering patterns obtained for stretched samples at room temperature in this way are presented in Figures 1 and 2 for VV polarization (polarizer and analyzer parallel to each other and to the stretching direction) and VH polarization (polarizer parallel the to stretching direction and analyzer perpendicular). HH and HV patterns were also obtained.
Nonhomogeneous Straining and Fracture Mechanism in a Filled Elastomer
Authors: Ronay Maria 
Published: February 2011

Abstract
This paper presents an experimental study of strain concentrations arising near the edges of elliptical cutouts in uniformly strained, flat strips of polyurethane rubber filled with a high volume percentage of an inorganic salt. The strain concentrations are studied under various conditions of uniform straining, for strains up to fracture initiation. The fracture mechanism at the root of the cutout is studied micrographically and it is found that the local fracture process is similar to that in unfilled elastomers, with consecutive rupture of highly deformed strands of the elastomeric material.
Fracture of Amorphous Polymeric Solids: Time to Break
Authors: Halpin J. C. 
Published: February 2011

Abstract
The failure theory of Bueche and Halpin is generalized and expanded to obtain a prediction of the time dependence of tensile strength and ultimate elongation. The model pictures rupture as propagation of tears or cracks within the material. The growth of a tear or crack is viewed as an ideally simple process in which the molecular chains at the tear tip stretch viscoelastically under the influence of a high stress concentration until they rupture. As a consequence, the failure process is a nonequilibrium one, developing with time and involving the consecutive rupture of the molecular chains. Substantial support for the theory is found by comparing the theoretical prediction with experimental results obtained for SBR and EPT. In addition, it is experimentally demonstrated that delayed and forced rupture experiments can yield qualitatively identical data for viscoelastic bodies. Also discussed is the basis for the approach to the nonlinear response of a viscoelastic body required here in the development of a fracture theory.