bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Degree of Neutralization on the Properties of Ionic Thermoplastic Elastomer Based on Sulfonated Maleated Styrene-Ethylene/Butylene-Styrene Block Copolymer
Authors: Ghosh Swapan K. , Bhattacharya A. K. , De P. P. , Khastgir D. , De S. K. , Peiffer Dennis G. 
Published: February 2011

Abstract
Novel block copolymer ionomers having both carboxylate and sulfonate groups in the same polymer backbone were obtained by sulfonating maleated poly (styrene-(ethylene-co-butylene)-styrene) block copolymer (m-SEBS), followed by its neutralization with barium acetate. The effects of the degree of neutralization on the properties of the ionomers were studied. Infrared spectroscopic studies confirm the formation of both carboxylate and sulfonate salts and the occurrence of the sulfonation reaction in the para position of the benzene rings of polystyrene segments. Dynamic mechanical thermal analyses show the presence of a high temperature rubbery plateau, particularly at high degree of neutralization, in addition to the glass-rubber transitions due to the polystyrene (PS) and ethylene-butylene (EB) phases. Tg of the PS block remains unchanged and tanδ at the Tg gradually decreases with increasing the degree of neutralization. But Tg of the EB block gradually increases and tanδ at the Tg marginally increases. The decrease in tanδ at δ of the PS block is ascribed to the stiffening of the polystyrene segments on neutralization.Increase in the degree of neutralization causes formation of ionic crosslinks which increases the Tg of the EB block. Dielectric thermal analyses show that incorporation of ionic groups plays an important role in the temperature dependence of the dielectric constant of the ionomers. At lower degrees of neutralization (25 and 50%), the ionomers behave like the base polymer in the sense that dielectric constant increases at elevated temperature(&gt;120°C). At higher degrees of neutralization, however, the increase in dielectric constant in the high temperature region is restricted due to the formation of the rubbery network arising out of the ionic aggregates. Transmission electron micrographs reveal that on neutralization the domain shape changes from predominantly cylindrical type to exclusively spherical one and at 100% neutralization the diameter of the spheres ranges from 15 to 20 nm. Processability studies show that as the degree of neutralization increases, the melt viscosity of the ionomers increases. The tensile strength, hardness, modulus and tear strength increase but the elongation at break and tension set decrease with increase in the degree of neutralization. Thermal stability of the polymers increases with the degree of neutralization. Reprocessability studies show that the ionomer can be recycled without fall in properties. The barium salt of sulfonated maleated SEBS at higher degrees of neutralization (75 and 100%) behaves as an ionic thermoplastic elastomer.
Better Process Description for the Extrusion of Silica and Carbon Black Compounds
Authors: Limper A. , Schramm D. 
Published: February 2011

Abstract
In comparison to plastics processing, rubber processors handle a much more complex material. Due to active fillers used in rubber compounds, such as carbon black and silica, in some cases extraordinary filler/filler interactions occur. In general the multi-component system leads to a very complex rheological behavior. If silica compounds e.g. are processed the chemical modification of the filler surface (by organosilanes) has to be taken into account. By this the rheological behavior of the material changes dramatically. All these circumstances make rubber processing to a very complex theme. This paper presents results which are obtained within an European research project. The work is focussing on a better process description of the extrusion process of rubber compounds. It handles both applications of the extrusion process, i. e. for technical rubber goods or for making tire parts like the extrusion of tread stripes. Hence in this paper a new approach for modeling the flow in the extruder screw will be presented. Using this as a simulation tool a systematic analysis of the extrusion process is possible in reasonable time. Another field of interest in this context is the rheological characterization of rubber compounds with a so called „Extrusion-Rheometer“. The advantages of this device will be shown for the investigation of processability and gathering representative rheological data for recalculations of screw and die flow in the extrusion process.
Rubber Chemicals Derived from Conjugate Addition. I. Syntheses of Novel 2-Thio-5-Amino Substituted Benzoquinones
Authors: Katritzky Alan R. , Odens Herman H. , Voronkov Michael V. , Rostek Charles J. , Maender Otto W. 
Published: February 2011

Abstract
Alkylthio-substituted benzoquinones were prepared from benzoquinone and mercaptans in 50–94% yields via NaIO4 oxidation of the intermediate hydroquinones. Subsequent addition of primary and secondary amines, in the presence of air as an oxidizing agent, gave a range of 2-thio-5-amino-substituted benzoquinones. No oxidation at sulfur was detected under the described conditions.
A Comparative Study of Styrene Polymerization in Deproteinized and Undeproteinized Natural Rubber Latex
Authors: Tho Nguyen V. , Kadir Mohd Omar Abd , Hashim Azanam S. 
Published: February 2011

Abstract
An investigation on in situ polymerization of styrene in deproteinized natural rubber (DPNR) latex and high ammonia natural rubber (HANR) latex was carried out. The ratio of styrene to dry rubber was fixed at 25 : 75 by weight. It was observed that, at reaction temperature of 60 °C and reaction time of 10 hours, the styrene-DPNR system could attain a high conversion of 97% without adding surfactant. The degree of chemical bonding estimated for the resultant polystyrene-DPNR dried material was about 80%. The styrene-HANR system, however, required the addition of surfactant to complete the reaction time; but the conversion was found to be relatively low, in the region of 66%. This low conversion could be attributed to the role played by the protein/lipid layer, which is virtually absent in the styrene-DPNR system.
Dispersion Studies of Agglomerates in Steady and Dynamic Flows of Polymeric Materials
Authors: Levresse P. , Manas-Zloczower I. , Feke D. L. 
Published: February 2011

Abstract
The hydrodynamic dispersion of spherical calcium carbonate agglomerates was studied under both steady and oscillatory shear-flow conditions. For a given intensity of steady shear flow, erosion rates were strongly influenced by the cohesive strength of the agglomerates with less cohesive, low-density agglomerates exhibiting faster erosion than high-density agglomerates. The dispersion kinetics were also affected by the extent of matrix infiltration within the agglomerate, with more infiltration resulting in reduced erosion rates. Experiments conducted in oscillatory shear flow fields provided new insights on local mechanisms of erosion.
Thermoplastic Elastomers and Rubber-Toughened Plastics from Recycled Rubber and Plastics
Authors: Liu H. , Mead J. L. , Stacer R. G. 
Published: February 2011

Abstract
An experimental investigation has been conducted to evaluate the use of recycled rubbers in blends for the development of new thermoplastic elastomers (TPE) and rubber-toughened plastics. The recycled rubbers were obtained from various commercial sources and included representatives from the EPDM, SBR, and NR/SBR blend families, as well as a range of particle sizes. A series of five different virgin polypropylenes (PP) were used as the plastic phase, representing a range of molecular weights and suppliers. Blends were prepared in a Haake Buechler batch mixer over a broad range of constituent fractions. Compatibilization and reactive blending techniques were used to improve the quality of the scrap rubber/plastic blends with respect to both mechanical and rheological properties. Results indicate that these blending techniques are required to obtain acceptable mechanical strength in the resultant materials. Additional parameters that significantly enhanced properties included elevating the blending temperature, reducing rubber particle size, and increasing PP molecular weight. This later conclusion was attributed to a lower degree of crystallinity in the PP phase that contributes to better blending between the phases.
The Fracture Behavior of Rubbery Vulcanizates: I. Single Component Versus Blend Systems
Authors: Qazvini N. Taheri , Mohammadi N. , Jalali A. , Varasteh A. , Bagheri R. 
Published: February 2011

Abstract
The tear energy and heat build up of NR, SBR and BR vulcanizates and their corresponding blends were measured at several temperatures via modified trouser tear and Goodrich flexometer experiments. In all single component samples, by increasing temperature from -10 to 125 °C, the fracture energy decreases, goes through a minimum and increases again. Nevertheless, in SBR and BR, a level off and a level off followed by second drop occur at higher temperatures, respectively. On the other hand, for aforementioned samples the heat build up decreases monotonically by raising the temperature. For two-component blends, the fracture energy and heat build up show different dependencies on temperature in comparison to single component systems. The fracture energy either increases, does not change at first and then decreases, or does not change as the temperature increases. While the heat build up is more or less constant by raising the temperature up to a certain point and then decreases but by a different path from single component vulcanizates. These peculiar behaviors are attributed to the competition between residual stress release and reduction of viscose loss term, while the temperature increases.
Weld-Line Strength of Rubber in Injection Molding: Effect of Injection Factors and Compound Characteristics
Authors: Seadan M. , Pongbhai P. , Thairaj P. , Kamtornkul T. Watana 
Published: February 2011

Abstract
The effect of injection molding system to weld-line strength in rubber O-rings was studied using a V-shape two-stage REP injection machine. Two types of injection molds were designed and built, a standard dumbbell mold with double gates and a circular cross-section O-ring mold. Several formulations of carbon black filled NR and SBR compounds were used and vulcanization temperature was either 180 or 200 °C throughout. The results show that mold cavity pressure, compound viscosity and compound scorch time are important variables for the weld-line strength of the products. The shot volume change had no direct effect on strength, but mold cavity pressure was an important factor; unfilled shot volume gave low cavity pressure thus lowering the weld-line strength of the O-rings. The compounds having 45 or lower Mooney viscosity, ML(1 + 4)120 °C, had the same weld area strength as that of the other regions of the O-ring, but the high viscosity compounds produced low weld-line strength. Only the compounds with Mooney scorch time shorter than 10 minutes gave low weld-line strength.
Cure Kinetics for Silane Coupled Silica Filled SBR Compounds
Authors: Jeong Jae-Hyeuk , Moon Chae-Woo , Leonov Arkady I. , Quirk Roderic P. 
Published: February 2011

Abstract
Vulcanization kinetics for silane-modified, silica-filled SBR has been investigated using the cure meter and swelling measurements to determine the crosslink density. The silane modifier was Si-69, bis(3-triethoxy-silylpropyl)tetrasulfane. To simulate the induction and curing periods as a function of temperature and compounding recipe, a three component kinetic model for curing was developed. The kinetic model consists of (a) curing in the bulk elastomer phase, (b) curing at the silica surface and (c) cross-phase curing between the bulk components and the silica surface. In order to describe the partitioning of reagents between the bulk and surface domains, the parameter reactive surface thickness,θ, was introduced into the kinetic model. An average value of 24.7 nm for θ was calculated from the kinetic data and the silica particle surface area. Physically significant model kinetic parameters were extracted from the experimental data using a cure meter at different temperatures for (a) bulk curing (no filler) using the model of Ding and Leonov; (b) curing at the silica surface with Si-69 (no sulfur); and (c) whole compound recipe. Crosslink density values determined from the shear modulus were in good agreement with results from equilibrium swelling measurements. Using experimental data from the cure meter studies at 160 and 180 °C, it was possible to calculate (predict) the cure meter data at 140 °C for several different recipes.
Rubber Recycling
Authors: Myhre Marvin , MacKillop Duncan A. 
Published: February 2011

Abstract
For both environmental and economic reasons, there is a continuing broad based interest in recycling of scrap rubber and development of recycling technologies. The use of post- industrial scrap is established as a systematic business. However, the disposal and reuse of scrap tires remains a serious environmental concern and a business opportunity. The method for reclaiming rubber utilizing aqueous alkaline solutions has been abandoned in North America because of environmental pollution hazards. The focus of more recent research is to apply processes that do not generate disposal hazards and that might be carried out directly in the product manufacturer's factory. The major process at the present time is to utilize the scrap rubber as a very finely ground crumb. Crumb is produced either by ambient temperature mechanical grinding or by cryogenic shattering. In general, the crumb rubber is combined with virgin elastomer compounds to reduce cost. However, there is some loss in physical properties and performance. This factor has motivated the search for cost effective in-situ regeneration or devulcanization of the scrap rubber to provide superior properties. Some progress has been achieved utilizing mechanical shear, heat and other energy input, and a combination of chemicals such as oils, accelerators, amines, etc. to reduce the concentration of sulfur crosslinks in the vulcanized rubber. The major application of scrap rubber, particularly as crumb, is outside the conventional rubber industry. More than half of the scrap is burned for its fuel value for generation of electricity and as a component in cement production. The utilization in extension of asphalt in road construction is now recognized to provide superior road performance and reduced cost. The simple use of crumb rubber as a component in artificial turf is developing into a significant industry. Rubber crumb is now widely utilized in rubber products such as mats, floor tiles, carpet undercushion, etc., where the crumb is rebonded using polyurethane or latex adhesives. Other applications, such as in landfill, concrete, thermoplastic blends, pyrolysis to generate carbon black and chemicals, are discussed. The tire industry does utilize a significant proportion of fine crumb rubber in tire compounds. This is likely to not increase much due to the concern about tire performance and safety. However, there is a serious interest by tire manufacturers to increase the use of scrap tire rubber, if the recycled rubber could be regenerated to improve compatibility and performance in tire compounds.
Microscopy of Rubber Products
Authors: Smith Ronald W. 
Published: February 2011

Abstract
This paper is a review of published literature containing some aspects of rubber product analysis using microscopy techniques. This includes close-up photography, photomicrography, photomicrography obtained from light optical microscope (LOM), scanning electron microscope (SEM) and transmission electron microscopy (TEM). Products represented are tires, belts, hoses, seals, rubber bands, balloons and some miscellaneous products such as a submarine hydrophone boot, rubber mat, shoe soles, tire curing bladder, and roofing membrane.
Structure Optimization in Colloidal Reinforcing Fillers: Precipitated Silica
Authors: Schaefer Dale W. , Chen Chunyan 
Published: February 2011

Abstract
In an attempt to elucidate the role of filler morphology in elastomer reinforcement, we use x-ray, light and neutron scattering to determine the structure of precipitated silica powders. We find the signatures of at least three levels of structure: primary particles, aggregates and agglomerates. By observing the evolution of the scattering profile during solution synthesis, we are able to identify when these structures appear. We also investigate the effect of ionic strength on morphology and find evidence for the interpenetration of aggregates on drying of powders prepared at low ionic strength. Using a reinforcement model by Witten, Rubinstein and Colby, we conclude that the ideal filler will consist of soft agglomerates made up of hard aggregates. Based on the dependence of morphology on synthetic protocol, we present strategies for design of efficient reinforcing fillers.
The Effect of Interphase Coupling on the Structure and Mechanical Properties of Silica-Siloxane Composites
Authors: Schaefer Dale W. , Vu Bic T. N. , Mark James E. 
Published: February 2011

Abstract
Silica-reinforced siloxane composites are synthesized with heat labile azo groups at the polymer-filler interface. The azo group serves as a “smart interface” in that it is responsive to heat. This system is used to assess the influence of interfacial chemical bonds on mechanical properties. By thermally severing the azo linkage, we can determine the influence of interfacial bonding on properties independent of other morphological factors. The virgin filler powders, azo-modified powders, silica-filled composites and azo-modified-silica-filled composites are characterized using small-angle x-ray scattering, IR spectroscopy, and scanning electron microscopy. Mechanical properties are correlated with the presence or absence of interface coupling, filler loading and thermal exposure. The data show that, at loadings above 5 wt%, elongation is enhanced in the azo-linked composites compared to the composites with bare fillers; modulus is enhanced at low silica loadings (&lt;5wt%) but is reduced at high loadings. On thermal clipping of the coupling agent, we find a slight enhancement of the ultimate elongation, but only at loadings above 5 wt%. We conclude that although interfacial bonding has a positive effect on reinforcement, the influence of physical interactions at the interface overrides that of chemical bonds.
A Note on the Gent Model for Rubber-Like Materials
Authors: Pucci Edvige , Saccomandi Giuseppe 
Published: February 2011

Abstract
We consider the strain energy recently proposed, on a phenomenological basis by Alan Gent to take into account limiting chain extensibility in rubber-like materials. We show that this model gives the simplest rational approximation for the reduced tensile force associated with uniaxial extension that satisfies the usual basic assumptions of continuum mechanics. Then by examination of the classical Treloar data on uniaxial extension of rubber, we explain why the Gent model cannot give good predictions for small and moderate strains. We propose some modifications and find a particular one which is able with a minimum number of phenomenological coefficients to give a very good fit to uniaxial data over the full range of deformations.
Mechanical and Viscoelastic Characterization of Hyperbranched Polyisobutylenes
Authors: Puskas Judit E. , Paulo Christophe , Altstädt Volker 
Published: February 2011

Abstract
Structure-property relationships were investigated in hyperbranched polyisobutylenes, in comparison with commercial linear butyl rubber. The gel-free, soluble hyperbranched polyisobutylenes, synthesized by living carbocationic polymerization, had molecular weights, Mw≈400,000 to 1,000,000 g/mol, molecular weight distributions, MWD ≈1.2 to 2.6, and branching frequencies, BR ≈ 4 to 60. The mechanical and viscoelastic characterization of these polymers revealed interesting properties, including the characteristics of crosslinked rubbers.
On the Filler Flocculation in Silica-Filled Rubbers Part I. Quantifying and Tracking the Filler Flocculation and Polymer-Filler Interactions in the Unvulcanized Rubber Compounds
Authors: Lin Chenchy J. , Hergenrother W. L. , Alexanian E. , Böhm G. G. A. 
Published: February 2011

Abstract
Filler flocculation was followed for silica filled compounds containing various alkoxy silanes and non-silane type polar additives. The methodology employed in this paper permitted a quantitative characterization of filler flocculation and polymer-filler interactions after heating the compound under conditions that simulated vulcanization. With the addition of trialkoxy silanes, the reduction of filler flocculation and the degree of polymer-filler interactions were found to depend on the type and the concentration of silane added, and on the mixing drop temperature (Td) used. Greater polymer-filler interactions and flocculation suppression were obtained with a compound containing a tetrasulfane when compared to that containing either a disulfane or a monofunctional-silane. Polar additives such as an amine compound and a sugar alcohol did not reduce the silica flocculation during simulated vulcanization because they were dewetted from the silica surface upon heating. The filler flocculation process was monitored by following the change of dynamic storage moduli using an on-line rheometer. The flocculation process order and process constant were extracted from the non-linear regression analysis of the kinetic data. These kinetic parameters were used to quantify the suppression of filler flocculation by the additives used. Filler flocculation was found not to be affected by the vulcanization process because it occurred prior to the onset of cure.
New Ultra High CIS Polybutadiene Through a Novel Neodymium Catalyst
Authors: Kwag Gwanghoon , Kim Aju , Lee Seunghwon , Jang Youngchan , Kim Pillsung , Baik HunJong , Yoon Dong-Il , Jeong Hoyoung , Lee Jung Goo , Lee Hosull 
Published: February 2011

Abstract
A significant improvement in the catalytic activity of Nd-based catalyst for 1,3-butadiene polymerization has been achieved using a novel neodymium compound, NdH(neodecanoate)4 (Nd( neodecanoate)3 (neodecanoic acid)). The neodymium compound was characterized with a matrix assisted laser desorption ionization (MALDI) mass spectroscopy, with a synchrotron X-ray absorption spectroscopy (XAS), and with computer simulations. A distinguished molecular ion peak (m/z=838.7, [M]) and a pronounced absorption edge are observed in the mass and in the Nd-LIII XANES(X-ray absorption near edge structure) spectra of NdH(neodecanoate)4, respectively, which evidence its monomeric structure. An active-center of the monomeric Nd-catalyst is fully optimized by density functional method (B3LYP/CEP-31G), in which neodymium(III) is coordinated with carboxylate, allylic active end, penultimate double bond, and chloride. The bond distances are Nd-C1 2.586 A˚, Nd-C4 2.741 A˚, Nd-C5 2.738 A˚, Nd-Cl 2.651 A˚, and Nd-O1 2.167 A˚, respectively. The Nd-catalyst shows a high activity (1.6×106 g/Nd md·h) and produces polybutadiene with 99% cis content. The ultra high cis polybutadiene produced by the Nd-catalyst exhibits excellent physical and mechanical properties such as high abrasion resistance, rebound, tensile properties and remarkably low heat build-up, which will greatly improve tire performance.