bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Zinc Dithiocarbamates on NR Vulcanization Accelerated by Thiocarbamyl Sulfenamides and Dibenzothiazyl Disulfide
Authors: Datta Rabindra Nath , Basu Dipak Kumar 
Published: February 2011

Abstract
The hplc studies with all their limitations have been employed to obtain information regarding the vulcanization of rubber accelerated by CTOS and MBTS in the early part of the reaction. It is noticed that even in the initial part of the induction period (the scorch safety, t2, of the recipe is 10.5 min), CTOS and MBTS react so rapidly with each other and also with rubber that at the end of 10 min we could detect only MBT, while the concentration of the other components formed in the reaction—namely, CTOS, OBTS, CPTD, BPTD, PMTU, CPTM, BPTM, etc.—decreased to an extremely low level. We noticed that under the experimental conditions, OBTS and CPTU have the same retention time. This naturally obscures the path for understanding the individual effect of these accelerators. The sharp disappearance of OBTS, associated with the abundant formation of MBT and nonavailability of CPTU (from CPTD, Figure 11b), gives testimony to the fact that the unsymmetrical thiourea (PMTU) rather than the symmetrical one (CPTU) is solely formed in the vulcanizates under discussion. The accelerating as well as retarding effect of thiourea has been reported by Dućhac^ek in the vulcanization of NR. Substituted thiourea, namely, bis(oxydiethylene) thiourea, has also been shown to influence the vulcanization of SBR in the presence of a mixture of accelerators formed by the early reaction of OTOS and OBTS. The influence of PMTU, however, remains to be investigated, and studies in this line are being pursued. Also, we could not isolate the effect of MDB from that of CPTD, since both of them have the same retention time. From our experience, we know that in comparison with CPTD, the proportion of MDB formed under the experimental conditions is very low and, hence, it is believed that CPTD plays the major role. It has also been observed that BPTD rapidly transforms into BPTM which, as noticed by us, also influences vulcanization. It is concluded that in the binary system containing CTOS and MBTS, the intermediate accelerators, OBTS, CPTD, and BPTD play a vital role, and their growth and decay, either in the presence or absence of the ZDC, control the fate of the vulcanization reaction.
Natural Higher Fatty Acid Soaps in Natural Rubber Latex Concentrate and Correlations to Other Latex Variables
Authors: Jurado C. W. , Mayhan K. G. 
Published: February 2011

Abstract
The amounts and types of HFA soaps found in latex did not vary greatly from sample to sample. Greater than 95% of the free HFA soaps were associated with the rubber phase of the latex. The distribution of fatty acid soaps were markedly different in the serum and latex samples. About 80–90% of the HFA soaps are in their free form, but only about 50% of the furanoic acid was in its free form. Titration results agree fairly well with the GC results and indicate that titration can be a useful measure of HFA.
A Simple and Rapid Method for Determination of Guayule Rubber
Authors: Grinberg Sarina , Shaubi Eleonora 
Published: February 2011

Abstract
An improved turbidimetric analytical method for guayule rubber was developed. The method is simpler and faster than previously developed turbidimetric methods, and enables the use of commercial solutions of the rubber. Unlike Traub and Perry, who used diisobutyl ketone for extraction of guayule rubber for turbidimetric measurements, we used hexane, which did not extract aromatic compounds along with the rubber, thus giving the best yield of spectrally clean rubber. Propanol is our precipitant of choice for turbidimetric assay of rubber, since it is also good as a colloid-protection agent.
Mechanisms of Antiozonant Protection: Unextractable Nitrogen in Aged Cis-Polybutadiene Vulcanizates
Authors: Lattimer R. P. , Gianelos J. , Diem H. E. , Layer R. W. , Rhee C. K. 
Published: February 2011

Abstract
Rubber (BR) vulcanizates containing DOPPD antiozonant and DPG accelerator have been aged under various conditions, and the soluble constituents have been removed by acetone extraction. Small amounts of nitrogen become bound to the rubber network as a result of side reactions associated with vulcanization. Additional nitrogen becomes bound to the rubber during aging. The bound nitrogen level is greater in (a) dynamic as compared to static testing, and (b) an ozone atmosphere as compared to air or nitrogen. We believe that the principal reason for nitrogen becoming bound during aging is the trapping of macroalkyl radicals by aromatic amine-derived species (e.g., nitrones). The results of this work are consistent with previous studies in our laboratory that indicate a combined “scavenger-protective film” mechanism is principally responsible for antiozonant protection. We believe it is unnecessary to invoke reactions involving antiozonant and ozonized rubber to explain the results of “unextractable nitrogen” experiments.
Inflation Characteristics of Unvulcanized Gum and Compounded Rubber Sheets
Authors: Kong Dancheng , White James L. 
Published: February 2011

Abstract
The inflation of rubber compound membranes to fill molds has a long history in rubber processing. There have, however, been few basic experimental studies of this topic. This free inflation of vulcanized rubber sheets was studied by Treloar and Rivlin and Saunders during the 1940's and 50's where it was used to investigate the form of the stress-strain relationship. Rivlin and Saunders sought to fit nonlinear elastic constitutive equations to data obtained at small inflation levels. In the early 1970's Denson and his coworkers utilized the inflation of unvulcanized polyisobutylene membranes to apply this as a procedure to evaluate biaxial and planar extensional viscosities. Similar studies were made by Maerker and Schowalter. These studies all involve free inflation of membranes. These studies of inflation of raw gum polyisobutylene sheets only looked at relatively small deformation levels where a hemispherical shape or less was achieved. Failure mechanisms in similarly inflated vulcanized SBR 1502 rubber sheets were described by Dickie and Smith. These authors did not describe the shapes of the inflated sheets. There seem to be no studies of inflation of rubber membranes into molds or useful equivalent studies of molten plastics such as thermoforming. It is the purpose of this paper to present a basic study of the inflation of membranes of various gum and compounded elastomers. We observe the manner in which the membranes freely inflate into air and also the manner in which they fill molds of various shapes. We begin with qualitative considerations but will also present quantitative measurements. Biaxial elongational viscosities have been estimated.
Characterization of Elastomers and Rubber Chemicals by Modern NMR Techniques
Authors: Komoroski R. A. , Shockcor J. P. , Gregg E. C. , Savoca J. L. 
Published: February 2011

Abstract
High resolution NMR has undergone a revolution in the last ten years or so. The ability to manipulate spin systems to a high degree in the pulse FT NMR experiment, coupled with advances in NMR computing systems, has led to the design of many multipulse and two-dimensional (2-D) NMR experiments which can provide considerably more information than a standard spectrum. In addition, experiments to obtain high resolution NMR spectra of solid materials have opened a whole area of chemistry to NMR. The new interpretive techniques for spectra obtained in solution have been applied to synthetic polymers or polymer chemicals only recently. However, the solid-state methods already have seen wide application in the polymer area. In this report, we describe some work from our laboratory employing some of these advanced methods in both solution and the solid state. This is not meant to serve as a detailed discussion of the techniques employed, but rather as an introduction to potential applications in the rubber and polymer industries.
Recent Advances in the Phenomenological Theory of Rubber Elasticity
Authors: Ogden R. W. 
Published: February 2011

Abstract
We have shown that representations for the strain-energy function in terms of the stretches λ1, λ1, λ1, with particular reference to the Valanis-Landel hypothesis, provide a very good correspondence between theoretical stress-deformation relations and existing experimental data for a variety of different deformations of rubberlike materials. The stress-deformation relations themselves have a simple structure which makes for clear interpretation of the experimental results. As was emphasized in Section II.B., however, more data from biaxial tests on rubberlike materials of varying constitution are needed to support those already available. Also, further data from a variety of different experiments in which inhomogeneous deformations occur would be valuable. Finally, with reference to the effects of compressibility, data relating to volume changes—possibly from biaxial tests in the presence of hydrostatic pressure—would enable a more systematic approach to the construction of strain-energy functions for compressible materials to be pursued.
Ultimate Tensile Properties of Segmented Polyurethane Elastomers: Factors Leading to Reduced Properties for Polyurethanes Based on Nonpolar Soft Segments
Authors: Speckhard T. A. , Cooper S. L. 
Published: February 2011

Abstract
Factors that could explain the lower tensile properties of nonpolar soft-segment-based polyurethane block copolymers relative to those of conventional polyether or polyester polyurethanes have been examined. Many of the materials studied in the literature have suffered from the use of soft segments with poor functionality, which has led to low molecular weight, network defects, and an unfavorable amount of crosslinking. Additionally, most of the materials have been based on soft segments whose molecular weight appears to be too high to obtain optimum properties. Polyurethanes based on nonpolar soft segments are also likely to suffer from premature phase separation during polymerization leading to low molecular weight and compositional heterogeneity, especially if the reaction is done in bulk. The lower soft-segment glass-transition temperature of, in particular, the polydimethylsiloxane polyurethanes can also contribute to their lower tensile properties at room temperature. However, if differences in the soft-segment glass-transition temperatures are accounted for by comparing samples at equivalent values of T−Tg and other parameters are optimized, it appears that only a lack of soft-segment crystallizability under strain and possibly an excessively high degree of phase separation are inherently limiting the tensile properties of nonpolar soft-segment-based polyurethane block copolymers. The limited amount of available information concerning the effects of many of these factors suggests a need for additional work in this area.
Electrical Conduction in Carbon Black Composites
Authors: Medalia Avrom I. 
Published: February 2011

Abstract
Electrical conductivity is important in many rubber and plastic compounds including antistatic applications, wire and cable sheathing, and shielding against electromagnetic interference (EMI). Elastomers and plastics are insulators (dielectrics) to which conductivity is imparted by addition of a finely divided or colloidal filler of high intrinsic conductivity, such as carbon black. Over the years, there has developed a sizable body of information regarding measurement of conductivity, and the factors which affect it in such compounds or composites. With regard to the physical processes involved in the conduction of electricity, various mechanisms have been proposed by various authors. It appears that many physical processes can be involved and that the dominant process depends upon the composition of the composite and the conditions of measurement. The purpose of this review is to survey the proposed mechanisms of conduction in composites of carbon black and nonconductive polymers, taking special note of recent theoretical advances, and to examine the effects of the properties of the carbon black and the composition of the composite.
Application of Electron Beam Radiation Technology in Tire Manufacturing
Authors: Mohammed S. A. H. , Walker J. 
Published: February 2011

Abstract
Electron beam radiation is used in various industries for a number of reasons. In the rubber industry it is used primarily for its ability to crosslink certain polymers and thereby to provide either “green strength,” by causing partial vulcanization (precuring), or “elastomeric properties,” by fully vulcanizing (curing). Although the latter function has potential importance, the precuring function has more practical application at this stage in the development of the technology and is particularly valuable in the radial tire building process. The electron beam vulcanization, or precuring of rubber products, is usually accomplished continuously, on-line, at high throughput rates, following extrusion or calendering operations. This paper reviews the chemistry involved, the response of polymers, and the effects of compounding for electron beam radiation processes. The type of equipment used in the tire industry, the process variables, and the methods used to measure the energy input into compounds exposed to radiation are also described. As an example of the utility of this process, electron beam radiation of halo-butyl inner liners used in radial ply tires is discussed.
Carbon Black Treadwear Ratings from Laboratory Tests
Authors: Dannenberg E. M. 
Published: February 2011

Abstract
It has been seen from the above survey that a few of the treadwear predictor correlations have the required accuracy to provide a satisfactory alternative to road testing of tires for the wear performance of carbon blacks, depending on requirements and circumstances. Correlations based on laboratory rubber testing of rubber mixes and tread compounds are to be preferred over those based solely on carbon black colloidal and morphological measurements. In the author's opinion, Cotten and Dannenberg's correlation of treadwear index with Angle Abrasion measurements of 30 phr compounds and heated bound rubber, and Westlinning and Wolff's correlation with rebound resilience, and the Monsanto Rheometer determination of αF are satisfactory in most instances for the prediction of the treadwear index behavior of carbon blacks.
New High-Temperature Thermoplastic Elastomers
Authors: Chen Augustin T. , Nelb Robert G. , Onder Kemal 
Published: February 2011

Abstract
The unique reaction of carboxylic acids with isocyanates has made it possible to incorporate polyamide into some new thermoplastic elastomers such as PEA and PEEA. With these high melting, semicrystalline, hard segments, these elastomers have excellent thermal properties and higher application temperature ranges. Because of their easy processability, these polymers can be injection molded or extruded for a great variety of applications with conventional equipment.
Experimental Study of the Flow Characteristics of Rubber Compounds in Extruder Screws
Authors: Brzoskowski Ryszard , White James L. , Weissert Frederick C. , Nakajima Nobuyuki , Min Kyonsuku 
Published: February 2011

Abstract
The application of screw extrusion to rubber compounds probably dates back over a century. Rubber extrusion has been an area of industrial importance throughout this period. Technological innovation continues in this area, as may be seen in a recent review by Johnson. However, there have been only a few basic studies on the flow characteristics of rubber screw extruders. Many more extensive investigations on the working of plastics screw extruders have been carried out. The latter researches are summarized in the volumes by Tadmor and Klein and Tadmor and Gogos. The basic mechanisms of flow of plastics in screw extruders were first revealed in experimental studies by Maddock. He fed the screw with pigmented pellets, pulled it from the barrel with the plastic strips in it, which were then unwound and cross-sectioned. There seem to be few such similar published investigations for rubber compounds. We are only familiar with the work of Menges and Lehnen. It is our purpose in the present paper to initiate a fundamental study of flow mechanisms in rubber screw extruders. We will proceed by carrying out the Maddock procedure but with rubber strips containing markers, then vulcanize the rubber compounds in place, and pull out the screws. The placement of the rubber will be noted, and the rubber sections will be examined for their flow patterns. The paper extends our earlier marker experiments on flow of rubber compounds through dies.
Newtonian Simulation and Dimensional Control of the Single Roller Die Extrusion Line
Authors: Stevenson J. F. 
Published: February 2011

Abstract
A single roller die consists of a fixed plate die bounded on one edge by a rotating cylinder. Material is forced through the die by a combination of pressure flow from an extruder and drag flow by the roller. Extrusion lines for tire components have traditionally been controlled by manipulating the size (cross-sectional area) of the extrudate through adjustments of the line speed relative to the screw speeds for cold-feed extruders or feed-strip widths and/or mill speeds for hot-feed extruders. Intentional changes in shape (ratios of dimensions normalized for size change) required altering the die geometry. Sources of variation in size and shape during extrusion include transients during start up, property changes within and between batches, short-term cycling of output rate, temperature cycling and drift, and inadequate control of independent variables such as screw and line speeds. The objective of this paper is to demonstrate how a single roller die line can be used to control independently two categories of dimensions (e.g., thicknesses and widths). This independent control necessarily requires that at least two other variables be manipulated, in this case, screw speed and roller die speed.
On the Role of Nonlinearity in the Dynamic Behavior of Rubber Components
Authors: Harris J. , Stevenson A. 
Published: February 2011

Abstract
This paper has discussed the transmissibility behavior of rubber mounts with reference to nonlinearity originating from the material composition and from the geometrical design. It has been shown that in many cases, linear assumptions can be made, provided the limitations of these assumptions are understood. In this case, design can proceed as for a linear spring. Finally, there is some indication of how the nonlinear behavior can be exploited to advantage in the design of novel suspension components.
Buckling and Postbuckling of Elastomeric Components: Tactile Feel in Electric Switches
Authors: Padovan Joe , Schrader Mark , Parris Joel 
Published: February 2011

Abstract
Within the range of the parameters of the switch designs considered, only very slight cocking of the switch structure occurred. Thus, with minimal off-axis cocking, the axisymmetric assumption remained valid, resulting in a considerable finite-element economization when compared to a full three dimensional model. Some switch designs encounter localization problems, such as surface folding and stiffness mismatches. Mesh refinement is not a general panacea for these localization problems. Regardless, a fold of this type or stiffness mismatch is generally indicative of a potentially poor switch design, with the possibility of associated fatigue problems. For the switch designs considered, the peak strains were found to be less than 70 percent; thus the Mooney-Rivlin and Ogden material models yielded essentially similar results. Furthermore, a Hookean material model may be adequate for some purposes, because the tactile-feel response was found to be dominated more by switch geometry than anything else. Overall, we have seen that combining FE analysis together with the full continuum-constitutive-boundary formulation can successfully address the problem of buckling and postbuckling of elastomeric structures. In the case of switches, such behavior is an intrinsic property. This is an interesting contrast with traditional structures.
Thermo-Oxidative Degradation of Thick-Walled Rubber Materials Studied by IR-Technique and Computed X-Ray Tomography Scanning
Authors: Mattson Bengt , Stenberg Bengt , Persson Sture , Östman Erik 
Published: February 2011

Abstract
Natural rubber cylinders vulcanized with two different systems, TMTD, which is an efficient vulcanizing system (EV system) and S/CBS, which is a conventional system, have been studied with respect to thermo-oxidative aging gradients, by the ATR-IR-technique (attenuated total-reflection infrared spectroscopy), computed x-ray tomography scanning and swelling. Observed aging processes are dominated by the formation of an oxidized layer whose low permeability to oxygen protects the interior of the material from oxidative aging processes as long as it is intact. The time to the formation of the oxidized layer is the major reason for the differences in the aging gradients. The oxidized layer is formed rapidly in the conventional system, whereas the formation is inhibited by dithiocarbamates in the EV system. Oxygen therefore diffuses into the EV materials, giving deeper oxidative aging than in the conventional materials at the same temperature. The conclusion drawn from the results of this study is that an earlier formation of an oxidized layer is advantageous with respect to thermo-oxidative aging of the bulk. Although it must be stated that, due to the better thermal stability of an EV system and to the poor mechanical properties of an oxidized layer, no objection is here raised to the accepted view that an EV system has superior aging properties.
Characterization of Fillers in Vulcanizates According to the Einstein-Guth-Gold Equation
Authors: Wolff Siegfried , Donnet Jean-Baptiste 
Published: February 2011

Abstract
1. Up to now, the application of the Einstein-Guth-Gold equation seemed to be limited to inactive fillers. 2. However, in the form of Equation (6), it describes with high accuracy the moduli of vulcanizates containing active fillers as a function of the filler volume fraction at least up to ϕ=0.22 at uniaxial elongations and for any given value of λ. 3. The effectiveness factor ƒ is independent of crosslinking density, but is dependent on deformation, temperature, and the surface activity of the filler. 4. If ƒ as a function of elongation is known, the respective stress-strain curves of filled networks can be calculated in advance for any given crosslinking density. 5. The interpretation of the effectiveness factor will require further investigations, especially with regard to the influence of the structure and surface activity of the filler.