bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Feasibility of Using Supercritical Fluid Extraction for the Determination of Total Extractables in Styrene-Butadiene Rubber
Authors: Sekinger J. K. , Ghebremeskel Ghebrehiwet N. , Concienne L. H. 
Published: February 2011

Abstract
Supercritical fluid extraction (SFE) is gaining popularity as an extraction technique. This report details the use of SFE for the extraction of extender oil, organic acid and antioxidant from styrene—butadiene rubber ( SBR ) Extraction parameters such as density, temperature, flowrate, and extraction time were investigated. The effect of sample size and modifier was also studied. Recovery and reproducibility data was generated for various SBR types, including oil-extended and carbon black filled polymers. Complete extraction was achieved in 30 minutes with 100 mg of sample using carbon dioxide. Sample masses of up to 1 gram were successfully extracted in the same time with the addition of a modifier.
Biscitraconimides as Anti-Reversion Agents for Diene Rubbers: Spectroscopic Studies on Citraconimide-Squalene Adducts
Authors: Datta R. N. , Schotman A. H. M. , Weber A. J. M. , van Wijk F. G. H. , van Haeren P. J. C. , Hofstraat J. W. , Talma A. G. , Bovenkamp-Bouwman A. G. V. D. 
Published: February 2011

Abstract
The mechanism of anti-reversion activity of biscitraconimides (BCI) during rubber vulcanization has been investigated. Biscitraconimides form crosslinks by reaction with chain modifications which are formed during the reversion process. These additional crosslinks compensate for the sulfidic crosslinks that are lost during the reversion. To allow structural assignments of the adducts formed between rubber and citraconimides, squalene has been used as a simple model system in combination with the currently used additives and sulphur. The products were identified as Diels—Alder adducts of conjugated polyenes, formed during reversion, with citraconimide. The nuclear magnetic resonance (NMR) spectroscopic assignments of the products are discussed. Furthermore the quantification of squalene-BCI adducts via NMR and mass spectrometry (MS) using 13C labelled 1,3-bis (citraconimidomethyl) benzene (BCI-MX) is described. It was found that under the applied conditions (2 h, 170 °C), approximately 80% of the citraconimide groups are converted into squalene-BCI adducts. Diels—Alder adducts are the main reaction products of the reaction. Products from an ene reaction are formed as minor component (less than 20%).
Hysteresis Friction of Sliding Rubbers on Rough and Fractal Surfaces
Authors: Heinrich Gert 
Published: February 2011

Abstract
The friction force generated between sliding rubber and rough surfaces has two components commonly described as the adhesion and hysteretic components, respectively. Under wet conditions, the adhesion component of the total friction is drastically reduced, whereas the hysteresis loss remains largely unaffected. Such situations arise in daily life during blocked wheel braking where tire treads slide over wet road asperities. The situation becomes more complex in Anti Blocking System (ABS) braking on wet roads where both adhesion and hysteresis components of the friction force act. We present a new model of the hysteretic friction coefficient of a sliding rubber sample over a rough or even fractal surface. The model uses the basic assumption that the damping properties of the dynamically strained rubber depend on specific properties of the surface profile through its power spectral density. This assumption is based on recent findings that the fractal texture model is the only one developed to date to successfully address the complete multiscale behavior of paved road surface texture. The spectral density depends on the ‘topothesy’ k of the surface and scales with the spatial frequency f according to a power law. The corresponding power is related to the surface fractal dimension D. The quantities k and D are scale-independent parameters that characterize the multiscale self-affine topography of road surfaces in the characteristic length scale range of interest. The influence of surface roughness on the frictional properties of the rubber depends on the sliding velocity and is described through a retarded coupling between relaxational modes of the polymer network and roughness modes of the surface. The results of the theory are discussed in comparison with recent experimental results of Grosch. Finally, we demonstrate how the fractal descriptor parameters of different test road pavements are used to compare tire traction measurements performed on wet test roads.
Phase Structure Changes in a Sheared Blend of High Molecular Weight Polybutadiene and Polyisoprene Elastomers
Authors: Remediakis Nikolais G. , Weiss R. A. , Shaw Montgomery T. 
Published: February 2011

Abstract
The flow-induced phase behavior of polyisoprene—polybutadiene elastomer blends is of concern to the rubber industry because of the wide practical applications of these blends. We have been investigating examples of these blends using a Rheo-SALS instrument in conjunction with light microscopy. The subject of this work was a high molecular weight, near-critical blend (35/65 ratio) comprising polybutadiene (Mn=413, 000) and polyisoprene (Mn=177, 000) (Blend II). The results were contrasted with those for a previously studied blend (Blend I) comprising polybutadiene (Mn=164, 000) and polyisoprene (Mn=125, 000), also near the critical composition at a 40/60 ratio. Both featured the same microstructure. Each was examined under quiescence and flow conditions. For Blend I at a 24 °C quench depth, the scattering pattern was the expected spinodal ring; which, upon shearing, changed to an H-shaped pattern and then to a bright streak in the vorticity direction. Direct observation showed that these patterns corresponded to a fibrillar structure aligned in the flow direction. Similar light scattering patterns were obtained after a temperature jump (24 °C) under steady-state shearing. With Blend II at a 40 °C quench depth, the scattering pattern was again a spinodal ring, but this changed on shearing to an anisotropic pattern having the shape of an “8” or a “butterfly.” The shape of this pattern depended on shear rate, and its origin was hypothesized to be phase domains following helical paths with axes aligned in the vorticity direction. The corresponding micrographs are consistent with this supposition, as is an instability phenomena observed in the parallel-plate rheometer at higher shear rates. These purely hydrodynamic phenomena should be kept in mind when interpreting observations of “flow-induced mixing” at lower quench depths.
Direct Adhesion between Electroless Nickel-P Plated Metals and NBR Compounds during Curing
Authors: Mori Kunio , Hirahara Hidetoshi , Oishi Yoshiyuki 
Published: February 2011

Abstract
In this study, an examination was made of the various causative factors for the direct adhesion between nickel-P alloy (nickel alloy) and acrylonitrile-butadiene rubber (NBR) compounds during curing. In a high sulfur curing system (SV), direct adhesion was found to depend on time of exposure to air and not to occur after more than 48 h of exposure. In the peroxide curing system (PV), there was no adhesion at all regardless of the exposure time. The addition of triazine thiols to NBR compounds resulted in adhesion between NBR compounds and nickel alloy for exposures exceeding 48 h. Typical curing systems such as SV, low sulfur curing (LSV), sulfurless curing (SLV), and PV gave good NBR-nickel adherends when the NBR compounds contained the monosodium salt of triazine trithiol (TTN). In these system, peel strength in the adherends increased with triazine thiols, to a maximum, and then decreased. This parameter was influenced by the chemical structures of triazine thiols, such as those containing thiol(-SH) and the sodium salt of thiol (-SNa) groups, and by the exposure of nickel alloy to air. Peel strength decreased with the formation of nickel oxides on the surface. When the nickel oxides were removed from the nickel alloy surface, peel strength was recovered. High peel-strength adhesion between NBR compounds with TTN and nickel alloy is due to the formation of interfacial bonds and reinforcement layers at the adhesive interface during curing.
Adherends consisting of NBR compounds with TTN and nickel alloy generally showed high heat resistance, oil resistance, and water resistance. The values for these parameters differed accordingly to the curing system and were optimal in the following order: SV &lt; SV with TTN &lt; PV with TTN.
The Effect of Network Formation on the Rheological Properties of SBR Modified Asphalt Binders
Authors: Lee Yong-Joon , France Lawrence M. , Hawley Martin C. 
Published: February 2011

Abstract
Styrene-butadiene rubber (SBR) was used to modify asphalt binders. The rheological and thermo-mechanical properties of the binders were investigated using rotational viscometry, dynamic shear rheometry, and thermal mechanical analysis. The optimum SBR content and mixing procedure were determined based on the rheological properties of the asphalt/SBR blends. The addition of 3–5% (w/w) SBR resulted in enhanced high temperature performance of the binders. The SBR progresses from a dispersed polymer to local networks to a global network with increasing SBR content. This phenomenon is exhibited in rheological properties such as complex modulus and melt viscosity. It is also verified visually by using a Laser Scanning Confocal Microscope. Because of this network formation, the binders showed a large increase in the complex modulus which indicates resistance to rutting.
The Microscopy of Catastrophic Tire Failures
Authors: Smith Ronald W. 
Published: February 2011

Abstract
Tires sometimes suffer catastrophic failure during travel on highways, resulting in a scatter of tire fragments along the pavement and berms. A large number of these fragments, including partial and whole tires, were collected and examined microscopically. The goal was to determine what sort of evidence might be “read” from these fragments via the optical stereo microscope using examinations of 7× to 60×. It was found that these fragments contain a wealth of well preserved information. Rubber tear lines and other fracture topographies are readable, allowing the failure analyst to determine directions of fracture/tear propagation which make it possible to postulate modes of separation. The features of torn surfaces that are normally encountered in laboratory testing are modified in tire failures due to the presence of adjoining compounds, complex shapes, and nonrubber components. Guidelines have been established to account for these complicating variables. A concept of “directional anisotropy” aids the analyst in understanding product failure surfaces. Additional items surveyed in this post mortem study were the condition at wire belt ends and indications of wire corrosion.
Metathetical Degradation and Depolymerization of Unsaturated Polymers
Authors: Marmo J. C. , Wagener K. B. 
Published: February 2011

Abstract
The employment of transition metal catalysts has been a viable route in the degradation and depolymerization of unsaturated polymers. Initially, unsaturated polymers were degraded with a catalytic system containing a transition metal and a Lewis acid cocatalyst (WCl6/SnBu4). Degradation chemistry was effective in reducing the molecular weight of the polymer, however, the classical catalyst system induces side reactions which generates ill-defined products. These side reactions were obviated by using a preformed alkylidene without a Lewis acid cocatalyst, and perfectly difunctional telechelics were synthesized.
Investigations into the Silica/Silane Reaction System
Authors: Goerl Udo , Hunsche Andrea , Mueller Arndt , Koban H. G. 
Published: February 2011

Abstract
Silica in combination with organosilanes (e.g. [bis(3-triethoxysilylpropyl)tetrasulfane] = TESPT) has recently become more important in tire applications. Their use in tire treads leads to an improvement in rolling resistance and wet traction. The requirements for the attainment of these properties are, that the triethoxysilyl groups of TESPT react with the silanol groups on the silica surface during compounding, and the polymer active groups react with the polymer during cure. The reaction of precipitated silica with this silane was investigated. The influence of various parameters on the reaction type and the reaction kinetics was considered. The results of the investigation obtained using 29Si-CP/MAS solid state NMR spectroscopy agree well with a horizontal reaction model in which a single siloxane bond is first formed with the silica surface (primary reaction). It is followed by condensation reactions between silanol groups of silane molecules which are already bound to the silica surface (secondary reaction). The kinetic studies data show a clear difference between the fast primary reaction and the slow secondary reaction. Both reactions become more rapid in acidic and alkaline pH ranges. The primary reaction accelerates up to a particular H2O content after which the rate remains constant. The secondary reaction keeps on accelerating with rising H2O content. Modification with different silane concentrations showed a higher rate constant at low concentrations.
Characterization of Sol and Gel in Hevea Natural Rubber
Authors: Tangpakdee Jitladda , Tanaka Yasukuki 
Published: February 2011

Abstract
The gel content of rubber from high-ammonia latex (HA-latex) decreased significantly after deproteinization with proteolytic enzyme. The addition of 1–2% ethanol in toluene solution reduced the gel content of rubbers from HA-latex, deproteinized HA-latex (HA-DP) and pale crepe. Transesterification of the rubber in toluene solution with sodium methoxide dissolved the gel fraction. The gel fractions solubilized after transesterification showed molecular weight distribution rich in low molecular-weight fraction. The Huggins k′ constant of the fractionated rubbers from solubilized-gels was in the range of 0.42–0.45, lower than that of the fractionated HA-DP of 0.5–0.8. This indicates that all the branch-points were decomposed by transesterification to form linear molecules. The Mn values of rubber chains assembling the gel was 5.5−8.3×105 by 13C-NMR measurements of the ratio between cis- and trans-isoprene units, which were comparable to the molecular weight between crosslinks, Mc, of 7−11×105 by swelling measurements. These findings suggest that the branching and crosslinks are composed of two types of branch-points, i. e. one by association or aggregation of proteins or oligopeptides at the initiating end and the other by ester linkages including phosphoric ester at the terminal end.
New Polybutadiene-Based Thermoplastic Elastomers: Synthesis, Morphology and Mechanical Properties
Authors: Dubois Ph , Yu Y. S. , Teyssié Ph , Jérôme R. 
Published: February 2011

Abstract
Well defined poly[styrene-b-butadiene-b-styrene] block copolymers (SBS) end-capped with poly(t-butyl methacrylate) (PtBMA) and poly (meth acrylic acid) (PMA) outer blocks, respectively, have been synthesized by the sequential anionic polymerization of butadiene, styrene and tBMA, followed by the selective hydrolysis of the PtBMA blocks into the corresponding PMA blocks. The structure-property relationships of these new thermoplastic elastomers have been investigated, with a special emphasis on the effect of the ester or acid outer blocks on the bulk properties.
As a rule, tensile strength is improved by increasing the length of the ester or acid outer blocks from 0 to 140 methacrylic units. Dipole—dipole intermolecular interaction of the PtBMA blocks and hydrogen bonding of the PMA blocks may account for enhanced mechanical properties. However, too high a degree of strong intermolecular interactions can constitute a deterrent to good phase separation. This is supported by morphological observations and loss in tensile properties when the relative content of the ester or acid outer blocks exceeds some critical value. In the case of a high acid content, DSC analysis shows two thermal transitions at −70 °C and 230°C for PBD and PMA blocks, respectively.
Anisometry Measurements in Carbon Black Aggregate Populations
Authors: Gruber Tyler C. , Herd Charles R. 
Published: February 2011

Abstract
Transmission electron microscopy with automated image analysis (TEM/AIA) was used to characterize the three-dimensional morphology and anisometry of carbon black aggregates. Individual carbon black aggregates were imaged at multiple goniometer angles, and their three-dimensional aggregate structure was modeled, yielding greatly enhanced morphological information. Aggregate size distributional properties were determined at multiple goniometer orientations for N300 and N600 series grades of varying aggregate structure levels. Aggregate projections were found to exhibit statistical decreases of 10 to 25% in area and perimeter with rotation. Decreases in other morphological parameters, including non-dimensional shape parameters, were also observed. In general, higher structure grades (aggregates) were found to display larger relative changes in morphological parameters with rotation than lower structure grades. Ramifications for conventional TEM/AIA and void-volume/polymer occlusion capacity measurements are addressed. Further analysis includes an assessment of aggregate anisometry on the TEM sample grid and new insights into the three dimensional nature of carbon black aggregate structure.
Surface Energy of Commercial and Pyrolytic Carbon Blacks by Inverse Gas Chromatography
Authors: Darmstadt Hans , Roy Christian , Kaliaguine Serge , Cormier Helga 
Published: February 2011

Abstract
The surface properties of carbon blacks obtained by vacuum pyrolysis of different used rubbers (CBp) and of commercial carbon blacks were measured by inverse gas chromatography (IGC). The dispersive component of the surface energy (γsd) and the specific interaction (Isp) of the recovered CBp were lower than γsd and Isp of the virgin carbon black initially present in the rubber. However, γsd and Isp of recovered medium surface area carbon black and of virgin low-surface-area carbon black were comparable. During the pyrolysis, carbonaceous deposits are formed on the CBp surface. A correlation between γsd and Isp and the amount of the carbonaceous deposits, measured by ESCA, was found, suggesting that the formation of these deposits is responsible for the decrease of γsd and Isp.
The Morphology of Rubber/Plastic Blends
Authors: Chung O. , Coran A. Y. 
Published: February 2011

Abstract
This study considers the rheological and interfacial effects on the phase morphology of the rubber/plastic blends during molten-state mixing, cold pressing, and compression molding. We utilized a specially designed tool to take a sample from the mixer and quickly cool it with little chance for coalescence. The work of this report is mainly concerned with soft rubbery compositions, which contain large concentrations of elastomeric phases. The morphologies of rubber/plastic blends having low concentrations of plastic or rubber can be explained by the understanding gained from work previously reported by others. The viscosity-matched and polarity-matched rubber/plastic blend systems give the finer states of dispersion, especially during the early stages of mixing. At intermediate concentrations of rubber, (e.g., 60 vol. %) co-continuous and laminar structures are frequently formed. The determinants of the concentration where the phase inversion occurs and the determinants of phase-domain dimensions near this phase-inversion concentration (e.g., a thickness of a highly shaped structure) are complex and can only be rationalized qualitatively. However, we were able to quantitatively relate phase-morphological dimensions to interfacial tension, rheology, and the observed type of morphology. When the hot batch is cold pressed, then a striated or laminar phase morphology is formed. Even very small particles deform greatly if the interfacial tension is low. Higher viscosities in the dispersed phase give rise to lesser deformations during cold pressing. During compression molding, the laminar structure transforms itself into a random co-continuous structure of vastly increased textural dimensions. This coarsening is greatest when polarities are most divergent and when the viscosities of the polymers are lowest.
Composites of Waste, Ground Rubber Particles and Poly(Vinyl Chloride)
Authors: Tipanna M. , Kale D. D. 
Published: February 2011

Abstract
Composites of poly(vinyl chloride) (PVC) were prepared with waste, finely ground printing rollers of nitrile rubber over a wide range of composition (up to 90% by weight of rubber component), through melt blending. The effect of different amounts of waste rubber on the tensile strength, % elongation, hardness, and flex crack resistance was studied. There was a considerable increase in the impact properties of PVC. Flex crack resistance was also significantly improved as the specimen did not crack even after 150,000 cycles for all composition containing more than 40% waste rubber. The waste rubber also imparted a plasticizing effect to PVC. The improvement in these properties could be due to interaction between PVC and the acrylonitrile part of nitrile rubber.
Degradation of Hydrogenated Styrene—Butadiene Rubber at High Temperature
Authors: Sarkar Mousumi De , Mukunda P. G. , De Prajna P. , Bhowmick Anil K. 
Published: February 2011

Abstract
Degradation of hydrogenated styrene—butadiene rubber (HSBR) having different levels of unsaturation has been studied over a wide range of temperatures under anaerobic and aerobic conditions using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), IR and NMR spectroscopy. TGA data indicate higher thermal stability of hydrogenated rubber as compared to SBR in nitrogen, although an anomalous behavior is observed in air due to crosslinking and oxidation of styrene—butadiene rubber (SBR). Isothermal data confirm the above observations. IR and NMR results reveal thermal isomerization, cyclization, oxidation, depolymerization, and chain scission processes. The nature and amount of products formed depend on the time and temperature of degradation and also on the level of hydrogenation of SBR.
The Density of Chemical Crosslinks and Chain Entanglements in Unfilled EPDM Vulcanizates as Studied with Low Resolution, Solid State 1H NMR
Authors: Litvinov V. M. , Barendswaard W. , van Duin M. 
Published: February 2011

Abstract
The network density in unfilled EPDM vulcanizates was studied by the following methods: low resolution, proton T2 NMR relaxation, Mooney—Rivlin analysis of stress—strain curves, and equilibrium swelling experiments. For the vulcanizates as such, the NMR method measures the total network density, which is composed of chemical crosslinks (CC) and of temporary (EN/TE) and trapped chain entanglements (EN/TR). The estimated molar mass of EPDM chains between apparent chain entanglements (EN) is 1900 ± 200 g/mol. For partially swollen samples, the NMR method determines the network density composed of CC and EN/TR. The CC density is obtained from the total density of network junctions and the measured entanglement density assuming that CC and chain entanglements are decoupled and additive. The contribution of CC, EN/TE and EN/TR to the total network density is estimated.