bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical Additives Migration in Rubber
Authors: Ignatz-Hoover Frederick , To Byron H. , Datta R. N. , De Hoog Arie J. , Huntink N. M. , Talma A. G. 
Published: February 2011

Abstract
Migration of compounding ingredients is an important factor in the overall properties and performance of rubber articles containing a number of layers for example, a tire, a hose or a conveyor belt. In certain cases, migration of compounding ingredients before, during and after vulcanization in rubber compounds can be of benefit. For example, waxes and p-phenylenediamines antiozonants rely heavily on the migration mechanism to provide optimum protection of rubber products during service against degradation by ozone. In addition, the dispersion of compounding ingredients such as oil, curatives, and antidegradants can be enhanced by diffusion within rubber. In other cases, however, diffusion across a rubber-to-rubber interface can be detrimental to performance. Diffusion will change the distribution of materials which in turn may result in changes in mechanical properties, loss in adhesion or antidegradant protection, and staining of light-colored products. Thus, a better understanding of the migration of chemical additives in rubber could provide the desired distribution of ingredients for obtaining the optimum compound performance.
Anisotropic Swelling of EPDM Rubber Discs by Absorption of Toluene
Authors: Azaar K. , Vergnaud J. M. , Rosca I. D. 
Published: February 2011

Abstract
Anisotropic swelling is observed when thin ethylene propylene diene monomer discs are immersed in a liquid such as toluene, whatever the percent peroxide acting as the curing agent ranging from 2 to 20. The process is studied either by experiments or calculation. The process of absorption is controlled by transient radial and longitudinal diffusion, with a concentration-dependent diffusivity and a finite and constant coefficient of convective transfer at the liquid-rubber interface. The problem is thus complex with a moving boundary since a rather high swelling takes place during the stage of absorption, leading to an increase in dimensions of the flat discs. The increase in the thickness of the discs is around 1.17– 1.18 times larger than that in the radius, at every time, while the diffusivity is the same for the radial and longitudinal transport. The extent of the change in the volume resulting from the toluene absorption varies from 1 to 1.5 depending on the value of the percent peroxide, the lower volume being obtained for the higher value of the curing agent The diffusivity is about the same whatever the percent curing agent. The state of cure is around 96 as obtained by calculation taking into account the heat transfer and the kinetics of the cure reaction. The kinetics of the cure reaction has been determined by measurements made either with a moving die rheometer run under isothermal conditions at three temperatures selected within the 170–190 °C temperature window, or a calorimeter in scanning mode. This fact can be explained by an orientation of the polymeric chains obtained during the cure, resulting from the pressure of the slabs of the heating press. Various percent peroxide as a vulcanizing agent have been used, e.g., 2, 10, and 20%.
Examination of Rubber-Brass Inter-Reacted Layer of Steel Cord by Cross Sectional TEM Observation
Authors: Yamauchi Michael T. , Shimizu Toshi , Doi Mitch , Yasunaga David , Nakayama Takenori , Okumura Kazuo 
Published: February 2011

Abstract
Cross sectional TEM observation was conducted with the aim of investigating the interfacial reaction of commercially manufactured steel cord and rubber during vulcanization. At the initial phase of the reaction, an inter-reacted layer was uniformly generated regardless of uneven brass thickness. As vulcanization progresses, the thickness of the interreacted layer becomes uneven, i.e. the thicker the brass plate, the thicker the inter-reacted layer becomes. Thus, the inter-reacted layer grows unevenly making a mirror image of the uneven brass plate, while a Zn-rich brass layer was formed between the brass plating and the inter-reacted layer.
Use of χ As a Function of Volume Fraction of Rubber to Determine Crosslink Density by Swelling
Authors: Hergenrother William L. , Hilton Ashley S. 
Published: February 2011

Abstract
A technique is described allowing a relatively simple determination of χ as a function of vr from swelling in heptane. A good measure of the true νe of the cured elastomer at all values of vr was demonstrated by substituting this relationship for χ in the Flory-Rehner (F-R) equation. The relationship was established over a wide range of vr values by using samples that had the νe of the cured elastomer determined by tensile retraction (TR). Applying this function to samples treated using the thiol probe method of Campbell gave an improved measure of the types of crosslinks present in sulfur-cured stocks. An identical equation describing χ as a function of vr in heptane was obtained with NR, EPDM and SBR containing up to a 0.31 volume fraction of carbon black (CB) and other fillers. The presence of up to 10 % of clay, talc, silica, resins or metal oxides in the CB had no noticeable effect on the relationship measured. However, when the filler contained about 50% silica a distinctly different slope in the relationship was found. The percent S1, S2 and Sx distribution measured was contrasted between measurements made by 13C NMR, swelling with χ = constant or χ as a function of vr.
Prevention of Rubber Degradation by Use of Microencapsulated Antioxidants
Authors: Kataoka Takahiro , Zetterlund Per B. , Yamada Bunichiro 
Published: February 2011

Abstract
A new approach of preventing evaporation and migration of antioxidants in rubber is presented. The antioxidant N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD) was microencapsulated in silica (MC6PPD) prior to compounding with the rubber. The microencapsulated antioxidants were characterized by differential scanning calorimetry and thermogravimetric analysis, indicating reduced rates of evaporation compared to free antioxidant. The stress-strain properties, flex cracking resistance and discoloration of the rubber were examined as samples containing equal amounts of antioxidant but in the different forms of 6PPD and MC6PPD. The results clearly indicated superior rubber performance in the case of MC6PPD, suggesting that antioxidant encapsulation is an effective technique to prevent rubber degradation due to aging.
Rheology of PVC Plastisol - VIII: Mechanism of Non-Linear Viscoelastic Behavior
Authors: Nakajima N. , Harrell E. R. 
Published: February 2011

Abstract
The mechanism of the strain-amplitude dependence (non-linearity) of viscoelastic properties of a PVC plastisol was examined. The range of amplitude was 0.02 to 10.24 and the range of frequency was 0.1 to 100 rad/s. The amplitude dependence of dynamic viscosity was very similar to its frequency dependence in that with the increase of amplitude or frequency it decreased first, reaching a minimum and then increased. In the preceding series of papers, the decrease of viscosity with the increase of frequency, i.e. pseudo-plasticity, was attributed to shear-induced phase separation into immobilized layer and mobile phase. In the present work, it is shown that the same mechanism is responsible for the decrease of viscosity with the increase of amplitude. The increase of viscosity with the increase of amplitude (after the minimum) is explained by the dilatation of the immobilized layer. Subsequently, the normal stress acting on the immobilized layer is calculated from the difference of the osmotic pressure between the mobile phase and immobilized layer. The shear deformation of the immobilized layer is estimated to be extremely small, although the deformation in the normal direction, i.e. the dilatation, is significant.
Gel Formation in Natural Rubber Latex: 1. Effect of (NH4)2HPO4 and TMTD/ZnO Additives
Authors: Tarachiwin L. , Sakdapipanich J. T. , Tanaka Y. 
Published: February 2011

Abstract
The rubber from commercially obtained high-ammonia latex (commercial HA-latex) increased in gel content significantly after long preservation of the latex with 1.0% w/v tetramethylthiuram disulfide (TMTD) and zinc oxide (ZnO). Deproteinization of the HA-latex did not decrease the gel content. The gel fraction of deproteinized commercial HA-latex (DPHA-latex) was not solubilized by toluene containing 1.0% ethanol, showing that the gel fraction is composed of chemically crosslinked rubber. The addition of (NH4)2HPO4, which is usually added to fresh latex (FL-latex) to remove excess amounts of Mg2+ ions by centrifugation, decreased the gel formation in FL-latex preserved with 0.6 % v/v NH4OH due to the removal of Mg2+ ions. The excess amounts of (NH4)2HPO4 accelerated the gel formation in preserved FL-latex and commercial HA-latex. The addition of 0.1% w/v TMTD/ZnO to preserved FL-latex treated with 5% w/v (NH4)2HPO4 caused an increase of gel content during storage. The gel formation in the commercial HA-latex during long time storage was presumed to be caused by excess amounts of Mg2+ ions, TMTD/ZnO and (NH4)2HPO4. Here, TMTD/ZnO accelerated the gel formation at the initial stage of storage, while (NH4)2HPO4 affected in long storage.
Understanding the Chemistry of the Rubber/Silane Reaction for Silica Reinforcement, Using Model Olefins
Authors: Debnath S. C. , Datta R. N. , Noordermeer J. W. M. 
Published: February 2011

Abstract
Although bifunctional organosilanes, particularly bis-(triethoxy-silyl-propyl) tetrasulfide (TESPT), are very efficient silica-rubber coupling agents, a high level is required to realize an optimum balance of processing as well as other performance characteristics. As to the functionality of TESPT in silica stocks, till today there remain numerous speculations rather than a clear understanding. An investigation has been carried out to understand the mechanism of the coupling of TESPT with rubber using a model olefin 2,3-dimethyl-2-butene (TME). Reverse Phase High Performance Liquid Chromatography in combination with Mass Spectroscopy shows that when pure TESPT is heated at 140 °C, the concentration of higher S-ranks in TESPT decreases, but in the presence of S8 the concentration of higher S-ranks increases. Treating TME with TESPT at 140 °C yields a mixture of crosslink products differing in the length of the sulfur-link. A mechanistic model for the reaction of TESPT with rubber is proposed, where TESPT donates activated sulfur-radicals, which can react with the rubber or model compound without the need for additional accelerators or vulcanizing agents. As ZnO plays no role in this mechanism, the TESPT merely acts as a sulfur-donor, not in the sense of an accelerator.
On Characterization of Anisotropic Elastomeric Materials for Structural Analysis
Authors: Gurvich Mark R. 
Published: February 2011

Abstract
Existing efforts in constitutive modeling of elastomers are primarily focused on isotropic materials. On the other hand, anisotropic elastic models were successfully developed for traditional composites with relatively small strains, where geometrical non-linearity of deformation may be ignored. There are, however, certain materials where neither large deformation and incompressibility nor anisotropy of material stiffness may be neglected. This study proposes a general constitutive approach to model both hyperelasticity (including incompressibility) and full anisotropy of material deformation in structural analysis. According to the proposed approach, an original hyperelastic anisotropic body is modeled as a combination of two hypothetical components (hyperelastic isotropic and elastic anisotropic ones). The proposed approach shows simplicity and convenience of practical application along with high accuracy of analysis. It may be easily implemented in computational analysis of 2- and 3-D problems using commercially available FEA codes without additional programming efforts. Analytical and computational implementation of the approach is considered on representative examples of elastomeric structures and rubber-based composites. Analytical solutions are shown for examples of biaxial tension of composites and inflation of a toroidal anisotropic tube. FEA solutions are discussed on examples of an inflated anisotropic sphere and non-uniform deformation of a composite layer. Obtained results are discussed to emphasize benefits of the proposed approach. Finally, a methodology to evaluate material parameters using corresponding test results is considered according to the proposed approach.
Testing of Compositional Distribution in Brominated Isobutylene Elastomers
Authors: Svec F. , Fréchet J. M. J. , Duvdevani I. 
Published: February 2011

Abstract
A method based on high-performance liquid chromatography (HPLC) method has been developed for the characterization of the compositional distribution of brominated poly(isobutylene-co-4-methylstyrene) and poly(isobutylene-co-isoprene). The desired separations in normal-phase chromatographic mode could only be achieved by using columns packed with specifically developed 10 and 3 µm porous monodisperse poly(2,3-dihydroxypropyl methacrylate-co-ethylene dimethacrylate) beads that have a homogeneous coverage of aliphatic hydroxyl groups. Linear gradients of tetrahydrofuran in hexane and dichloromethane in heptane were used respectively as the mobile phases for the selective elution of brominated poly(isobutylene-co-4-methylstyrenes) and brominated poly(isobutylene-co-isoprenes). In-column solvo-thermal treatment of the stationary phase further improved both selectivity and retention and enabled the easy detection and detailed quantification of differences in bromine content well below 1 mol %.
On the Filler Flocculation in Silica and Carbon Black Filled Rubbers: Part II. Filler Flocculation and Polymer-Filler Interaction
Authors: Lin Chenchy J. , Hogan Terrence E. , Hergenrother William L. 
Published: February 2011

Abstract
Filler flocculation and polymer-filler interaction in silica and carbon black filled rubbers containing different functional end-groups were investigated. Lithium-hexamethyleneimine initiated polymers terminated with a proton (HMI-P-H), SnCl4 (HMI-P-Sn), and a mixture of SnCl4 and tetraethyl orthosilicate (HMI-P-TEOS) were employed to determine the affinities of various functionalities toward fillers. Reduced filler flocculation was found for compounds of HMI-P-Sn and HMI-P-TEOS after thermal annealing at 171 °C for 15 minutes when compared to the annealed HMI-P-H stock. Curing at the same condition used for annealing gave further suppression of filler flocculation for HMI-P-TEOS stock by increased polymer-filler interaction during cure. Polymer-filler interaction was followed by examining G′ strain dependence and the differences in G′ obtained between HMI-P-Sn or HMI-P-TEOS and HMI-P-H (δG′). This treatment gave a peak maximum in the δG′ plot as a function of strain. The magnitude of the maximum in HMI-P-TEOS stock is double that of HMI-P-Sn stock and increased after thermal annealing. The compound tanδ temperature dependence showed higher hysteresis around the Tg transition and strong dependence at elevated temperatures was found for HMI-P-TEOS stocks. This increased polymer-filler interaction is manifested with increased 0 °C tanδ and reduced 50 °C tanδ which relates to the improved wet traction and rolling resistance for tires.
Effect of ZnO Particle Size on the Curing of Carboxylated NBR and Carboxylated SBR
Authors: Hamed G. R. , Hua K.-C. 
Published: February 2011

Abstract
A carboxylated nitrile rubber (XNBR) and a carboxylated SBR (XSBR) were mixed with zinc oxide particles of different specific surface areas (“S”, 35 m2/g; “M”, 3.5m2/g; “L”, 0.5 m2/g) and cure behavior at 165 ºC studied using oscillating disc rheometry. Without added zinc oxide, both raw rubbers slowly stiffen over many hours of heating. This is probably due to condensation of carboxyl groups to form anhydride crosslinks. XNBR compositions containing the finely divided “S” crosslink much more rapidly. Full cure is reached after about 10 minutes of heating. Cure rate decreases markedly as the specific surface area of the ZnO decreases. A composition containing “M” at twice stoichiometry requires about an hour to cure well, while with “L”, about 10 hours are required. In contrast, curing of the XSBR depends little on the specific surface area of the ZnO, either with “S” or “L”, curing is essentially complete after 30 minutes. After simply mixing ZnO into either rubber, it remains as a dispersed particulate. With XNBR, curing appears to be controlled by the rate of dissolution and diffusion of ZnO, while, with XSBR, reaction is not diffusion limited and may be confined to regions near particle surfaces.
The Compression of Bonded Rubber Disks
Authors: Anderson M. L. , Mott P. H. , Roland C. M. 
Published: February 2011

Abstract
Compressive stress-strain measurements are reported for bonded disks of natural rubber having shape factors (= d/4t, where d is the diameter and t the thickness) ranging from 0.87 to 12.95. The data are compared to various models for compressed rubber, utilizing the tensile and bulk moduli determined for this material. We find that for thin disks, the measured stiffness is less that the theoretical predictions by roughly a factor of two. A similar discrepancy was found previously, both for elastomers and semi-crystalline polymer films. However, for smaller aspect ratios, the difference between experiment and theory is less than the measurement error.
Zinc Loaded Clay as Activator in Sulfur Vulcanization: A New Route for Zinc Oxide Reduction in Rubber Compounds
Authors: Heideman Geert , Noordermeer Jacques W. M. , Datta Rabin N. , van Baarle Ben 
Published: February 2011

Abstract
Concern about the release of eco-toxic zinc species from rubbers into the environment leads to an increasing interest in potential substitutes. Although alternative metal oxides and zinc compounds as activators for sulfur vulcanization have been studied thoroughly, at present no viable alternative has been found to eliminate ZnO completely from rubber compounds, without significantly jeopardizing processing as well as performance characteristics.
In this paper, the application of a new activator for sulfur vulcanization will be discussed. This activator is developed based on the assumption that an increase in the availability of Zn2+-ions could lead to a considerable reduction of ZnO in rubber compounds. Montmorillonite clay was used as carrier material and loaded with Zn2+-ions via an ion-exchange process.
Application in a wide range of natural and synthetic rubbers has been explored. Results clearly demonstrate that this Zn-Clay can substitute conventional ZnO, retaining the curing and physical properties of the rubber products but reducing the zinc concentration with a factor 10 to 20. Model Compound Vulcanization studies have been used to gain an insight into the mechanism of this activator.
It can be concluded that systems with Zn2+-ions on a support represent a new and novel route to reduce the zinc level, and therefore to minimize its environmental impact significantly.
Filler Dispersion in Hyperbranched Polyisobutylene
Authors: Roland C. M. , Robertson C. G. , Nikiel L. , Puskas J. E. 
Published: February 2011

Abstract
The microdispersion of carbon black filler in linear and hyperbranched polyisobutylene (PIB) was assessed from dynamic mechanical and volume resistivity measurements. While no significant differences were observed in the carbon black concentration necessary for formation of a filler network, in comparison to the linear polymer, the highly branched PIB was found to have substantially more carbon black agglomeration. This occurs despite its higher viscosity, due to the relative inaccessibility of large portions of the molecule, as a result of the profuse treelike branching. The consequence is more extensive interaggregate interaction, and thus a larger Payne effect and greater mechanical hysteresis.
Elastomers for Shoe Applications
Authors: Ames Kimberly A. 
Published: February 2011

Abstract
This review covers the various polymeric materials now used to produce outsoles and midsoles for footwear. Thermoset rubbers are considered to be the best material in terms of performance, but many new materials are challenging in the marketplace, due to their ease of production and lighter weight. While the focus of this review is on improvements made in the last 15 years, the history of footwear and footwear materials is discussed to provide a background for the development of the various alternatives to thermoset rubber.
Biaxial Tensile Behavior of Rubber Vulcanizates: I. Silica and Gum Stocks
Authors: Kajiwara Kanji , Kameda Yoshihiro , Ikeda Yuko , Urakawa Hiroshi , Kawamura Takanobu , Urayama Kenji , Kohjiya Shinzo 
Published: February 2011

Abstract
We have studied the strip biaxial tensile behavior of natural rubber vulcanizates filled with silica by the conventional milling method and by the in-situ silica filling method. The rapid increase of both stresses along the stretching and the fixed axes after the initial stretching was observed on samples filled with a conventional silica by the milling method. Low strain dependence of stresses in the successive strain regions was followed by the rapid increase of the stresses at the higher deformation region. On the other hand, we did not observe such behavior for the samples filled with silica generated in-situ in the rubber matrix before curing. The transmission electron microscopic measurements showed that a highly developed aggregated structure of silica particles was suggested in the conventional silica filled samples and just a simple aggregation was suggested in the case of the in-situ silica filled samples. The differences between samples reinforced with two different filling methods in low tensile region are mainly attributed to the aggregate structure of the silica particles dispersed in the rubbery matrix. We estimated the functional form of the strain energy density function for the samples filled with silica in intermediate and large deformation regions:
=C10(I1−3)+C01(I2−3)+C20(I1−3)2
The estimated W was found to reproduce the experimental stress-strain curves in intermediate and large deformation region. The relative contributions of three terms in the estimated W for the samples prepared by the in-situ method show the different dependence on the silica content from those of the samples containing silica mixed by the conventional method.
Low Cis Polymerization of Butadiene Using TiCl4 and Bisupported with SiO2/MgCl2(Ethoxide Type)/TiCl4 Catalysts
Authors: Zohuri G. H. , Mohebat R. , Jah R. Jam , Ahmadjo S. 
Published: February 2011

Abstract
To obtain low cis polymer of butadiene (PBR), heterogenous and homogeneous Ziegler-Natta catalyst of TiCl4 were used. SiO2 and Mg(OEt)2 were used as supports for the heterogenous catalyst, while TiCl2 was used as a soluble catalyst. Triisobutylaluminium (TIBA) was used as a cocatalyst. Optimum molar ratio of Al/Ti = 1.5 : 1 and Al:Ti = 13 : 1 were obtained for TiCl4/TIBA and SiO2/MgCl2 (ethoxide type)/TiCl4/TIBA catalyst systems, respectively, regarding productivity of the catalysts. Effect of the temperature of 25–65 °C on polymerization was studied for the bisupport one; while for the TiCl4 temperature control was difficult. This could be due to the obtained high gel content of polymer. The highest yield of PBR was obtained at 55 °C using the bisupported catalyst. Addition of H2 as a chain transfer agent decreased cis%, gel content and the yield of polymer obtained. Increasing polymerization temperature when H2 was used was negligible, which had an affect on the gel content of the polymer. Productivity of the bisupported catalyst was higher than the TiCl4 catalyst itself and the polymerization temperature was under control as well. Polymer with cis content of 4 to 65% was obtained using different catalyst and different polymerization conditions.