bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Mixing Efficiency in a Multi-Cut Transfermix
Authors: Li Tao , Cheng Hongfei , Manas-Zloczower Ica 
Published: February 2011

Abstract
Three-dimensional flow patterns of a power-law model fluid in a Multi-Cut Transfermix were calculated. A particle tracking algorithm was used to study the dynamics of mixing. Distributive mixing efficiency was quantified in terms of length stretch distributions and average values. The influence of rotational speed and axial pressure difference on mixing efficiency, under constant output was analyzed. The mixing performances in the MCT was also compared with that in a single screw extruder with the same dimensions as the entrance region of MCT and operating at the same flow rate.
Chemical Interaction between Chlorosulfonated Polyethylene and Silica—Effect of Surface Modifications of Silica
Authors: Roychoudhury A. , De P. P. , Roychoudhury N. , Vidal A. 
Published: February 2011

Abstract
The surface of precipitated silica was modified by heat treatment (800°C, 4 h) and hexadecanol treatment. Diffuse reflectance infrared Fourier transform spectroscopic (DRIFTS) measurements reveal that the modification of the silica surface reduces the silanol content. Heat treatment causes condensation of the silanol groups forming siloxane linkages, while hexadecanol treatment causes esterification, thereby, shielding the free silanol groups. As a result, the modified silicas exhibit much less interaction with polar molecules (e.g. water, chloroform), compared to the unreacted silica. Bound rubber formation in the chlorosulfonated polyethylene (CSM)/silica system is also adversely affected by the modification of the filler surface. CSM upon heat treatment (180°C, 1 h) loses -SO2Cl groups and the modified polymer lacks in its ability to form bound rubber. Accordingly, it is believed that the rubber-filler interaction occurs between the silanol groups of the silica and sulfonyl chloride groups of CSM.
Kinetics of Morphological Development in Elastomer Modified Silica Xerogels
Authors: Beaucage G. , Guo L. , Hyeon-Lee J. 
Published: February 2011

Abstract
Acid-catalyzed, sol-gel chemistry is used to incorporate polysiloxane elastomers in ceramic gels in order to prevent pore collapse on drying. These rubber-modified, ceramic gels can lead to low-density nano-porous materials for uses such as thermal insulation. The morphological mechanisms by which these materials are toughened by elastomers is the focus of this paper. Structural development in these multiphase systems involves a complex interplay between nano-scale hydrolysis/condensation reactions and colloidal to macroscopic phase separation and network formation. The interplay between these morphological features as a function of reaction time is studied using microscopy as well as small-angle x-ray and light scattering. The initial reaction mixture is phase-separated on a micron scale due to the immiscibility of poly-siloxanes and water. At an early stage of the sol-gel reaction, mass-fractal domains in the nano-scale develop, while micron-scale phase-separated domains are diminished. Near the gel-point, a macroscopic network forms whose morphological features are strongly influenced by the presence of polysiloxane elastomer. A model is proposed for the interplay between these structural levels during growth.
Some Attempts to Force Poly(Dimethylsiloxane) Chains through Zeolite Cavities to Improve Elastomer Reinforcement
Authors: Pu Zhengcai , Mark James E. , Beaucage Gregory 
Published: February 2011

Abstract
The reinforcing effects of zeolites in poly(dimethylsiloxane) (PDMS) elastomers were characterized using two preparative approaches. In the first, end-functionalized polymer chains were blended into the zeolite, and were then endlinked into the required network structure. The second approach represented an attempt to force some chains through the cavities, by blending the monomer itself into the zeolite and then polymerizing it to obtain the PDMS elastomer. The two types of zeolite-filled PDMS were characterized using stress-strain measurements in elongation, equilibrium swelling, and small-angle X-ray scattering. The second synthetic approach did seem to give improvements in mechanical properties, particularly when the average cavity size of the zeolite particles was relatively large. Ascribing the observed improvements in reinforcement at least partly to the threading of some PDMS chains through the zeolites was supported by the results obtained in the swelling and scattering experiments.
Studies of Elastomer Oxidation via Thermal Analysis
Authors: Burlett D. J. 
Published: February 2011

Abstract
Elastomers are used in many industrial applications because of their remarkable toughness and elasticity. However, the source of these properties is also a weakness, in that loss of properties via oxidation is an important factor in their selection. Thermoanalytical techniques, such as differential scanning calorimetry (DSC), provide useful tools for the characterization of the stability of elastomers. DSC can not only be used to determine oxidative induction times under isothermal conditions but can also be used to determine apparent overall activation energies of the oxidation process. An evaluation of these techniques is made and the technique is used to compare the oxidation susceptibility of polybutadienes of different microstructure. The results of these DSC scans are interpreted in terms of the chemistry of the oxidation process using FTIR results.
Identification of Tackifying Resins and Reinforcing Resins in Cured Rubber
Authors: Kim Seung Wook , Lee Gae Ho , Heo Gwi Suk 
Published: February 2011

Abstract
On-line thermogravimetic analysis/Fourier transform-infrared spectroscopy (TGA/FT-IR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) were employed to identify the tackifying resins and reinforcing resins in cured rubber. Py-GC/MS gave better results in the identification of the resins than the on- line TGA/FT-IR method. The mass spectra of resins in cured rubber were characterized by comparing the mass spectra of the pyrolyzates of raw resins and those of cured rubber containing the resins. t-Butylphenol acetylene condensed resin, coumarone-indene, C5-oligomeric Escorez 1102, modified wood rosin, and reinforcing modified cashew resin were studied. The results show that on-line Py-GC/MS is powerful tool in the analysis of the resins in cured rubber. The diagnostic m/z values of the resins for direct analysis in cured rubber were summarized. Reasonable structural information for resins could be acquired by the characteristic fragmentation patterns.
Adhesion of Natural Rubber to Steel Substrates: The Use of Plasma Polymerized Primers
Authors: Boerio F. J. , Tsai Y. M. , Kim D. K. 
Published: February 2011

Abstract
Plasma-polymerized acetylene films are excellent primers for bonding natural rubber (NR) to steel substrates. The purpose of this research was to determine the mechanisms responsible for adhesion at the NR/primer interface. Interactions between natural rubber and plasma-polymerized acetylene films were simulated using model systems containing squalene (C30H50) or squalane (C30H62), carbon black, sulfur, stearic acid, N, N-dicyclohexyl-benzothiazole-sulfenamide (DCBS), cobalt naphthenate, and diaryl-p-phenylene-diamine. Analysis of plasma-polymerized acetylene films before and after reaction with model rubber systems was accomplished using Fourier transform infrared spectroscopy (FTIR). The importance of the unsaturation in the reaction was demonstrated by comparing the behavior of the two model systems. In the squalane-based system, squalane itself was stable throughout the reaction, with only a slight reaction with the antioxidant and sulfur. No significant reactions occurred between the squalane-based model system and plasma-polymerized acetylene films with the exception of slight adsorption of antioxidant and zinc and/or cobalt stearate onto the films. Reactions between plasma polymerized primers and the squalene-based model system were complex. Squalene itself went through double-bond migration. ZnO and cobalt naphthenate reacted with stearic acid to form zinc and cobalt stearates which then reacted with DCBS and sulfur to form zinc and cobalt accelerator perthiomercaptide complexes. These complexes reacted with squalene and with the primer film to form accelerator terminated, perthiomercaptide pendant groups and, eventually, short polysulfide crosslinks. Since there was little reaction of squalane-based model rubber compounds with plasma polymerized primers but extensive reaction of squalene-based models, it was concluded that an intermediate formed in that reaction was responsible for crosslinking between squalene and the primer in the model system and for adhesion at the NR/primer interface in an actual bond.
1H NMR Relaxation Studies of Cured Natural Rubbers with Different Carbon Black Fillers
Authors: Leisen J. , Breidt J. , Kelm J. 
Published: February 2011

Abstract
1H NMR relaxation data provide insight into the effects of carbon black fillers on the structure of polymer networks in products based on natural rubber so that accepted ideas concerning the interaction between elastomeric networks and active filling materials are confirmed. A new 1H NMR relaxation experiment allows the direct investigation of dangling chains within the polymeric network. In samples containing carbon black a motional anisotropy is observed for these chain ends, while dangling chains in samples without carbon black fillers show isotropic rotational motions. The parameter q′, quantifying the motional anisotropy, is suggested to be a measure of the physico-chemical interactions between elastomer and filler.
Homogeneous Zinc(II) Catalysis in Accelerated Vulcanization III. Degradation Modes of Mono- and Disulfidic Cross-Links
Authors: Nieuwenhuizen P. J. , van Veen J. M. , Haasnoot J. G. , Reedijk J. 
Published: February 2011

Abstract
This paper reports a Reaction-Stage-Modeling study dealing with degradation of mono- and disulfidic cross-links, providing new information about the molecular processes underlying the macrophysical phenomenon of reversion. The monosulfidic model cross-link (2,3-dimethyl-2-buten-1-yl)(2,3-dimethyl-1-buten-3-yl)sulfide was found to degrade at a relatively low temperature of 140 °C to yield olefins and α, β-unsaturated thioaldehydes. The latter species are not stable enough to be observed directly, but instead dimerize via an auto-Diels-Alder reaction to give a—fully-characterized—1,3-dithiin. The disulfidic model cross-link bis(2,3-dimethyl-2-buten-1-yl)disulfide was observed to degrade according to a previously unknown mechanism, involving a 1,4-hydride shift, to furnish a 1,3-dipolar intermediate. The reaction is catalyzed by bis(diethyldithiocarbamato)zinc(II), ZDEC, and the activation enthalpy ΔH‡ of the reaction has been determined to be ∼ 71(7) kJ mol− . Several dienophiles and dipolarophiles were applied to trap the α, β-unsaturated thioaldehyde and 1,3-dipolar intermediate, but neither was successful. Overall, this study has furnished direct evidence for degradation of mono- and disulfidic cross-links via hydrogen shifts and indicates, for the first time, in what way zinc complexes may cause cross-link degradation and induce reversion in rubber vulcanizates.
Homogeneous Zinc(II) Catalysis in Accelerated Vulcanization IV. The Mechanism of Cross-Link (De)Sulfuration
Authors: Nieuwenhuizen P. J. , van Veen J. M. , Haasnoot J. G. , Reedijk J. 
Published: February 2011

Abstract
This paper reports a detailed re-examination of the mechanism of zinc-mediated cross-link desulfuration by means of Reaction-Stage Modeling. Heating the model cross-link bis(2,3-dimethyl-2-buten- 1-yl)disulfide in the presence of catalytic amounts of bis(diethyl-dithiocarbamato)zinc(II), ZDEC, results in slow but definite formation of monosulfides displaying retention and isomerization of the double-bond position. The formation of monosulfides with retained double bonds implies that cross-link desulfuration occurs according to SNi reactions; whereas, the formation of isomerized monosulfides points to the operation of SNi′- and/or thione-like desulfuration reactions. Importantly, these observations constitute the first evidence for zinc accelerators acting as homogeneous catalysts in desulfuration. The activation energy for cross-link desulfuration of SNi reaction was established to be 86(16) kJ mol−1. In addition, ZDEC is reported to sulfurate model cross-links. The required sulfur atoms may originate either from desulfuration of other sulfides, or from elemental sulfur added to the mixture. Just as for cross-link desulfuration, zinc-mediated sulfuration was found to occur both with and without double-bond isomerization.
Elastomer Swelling in Mixed Solvents
Authors: Westbrook P. A. , French R. N. 
Published: February 2011

Abstract
A critical performance factor for elastomers in chemical service is absorption of solvents. Since swelling data are often limited to single component exposure, methods to estimate elastomer compatibility with mixed solvents have received considerable theoretical attention. The evolution of these methods is reviewed. Then, an alternative empirical procedure is proposed which is based upon a generalization of Flory's network-solvent phase equilibrium concept. The resulting linear and nonlinear partition coefficient models are used to predict swelling behavior of various elastomers in nearly ideal hydrocarbon solutions as well as other non-ideal solutions. Advantages of the current methods are that they utilize readily available swelling data of the elastomers in pure solvents and also thermodynamic data of the solution of interest. Adjustable parameters are required only when strong associative swelling agents are present. Finally, information regarding the chemical structure of the elastomer is not required.
Carbon Black Distribution in Rubber Blends: A Dynamic-Mechanical Analysis
Authors: Klüppel M. , Schuster R. H. , Schaper J. 
Published: February 2011

Abstract
The influence of phase morphology and carbon black distribution on energy storage and dissipation during dynamic excitations of rubber blends is discussed. It is shown that differences in the local stiffness of the phases in the glass transition regime of unfilled blends lead to characteristic deviations of the local strain from the external strain amplitude. These deviations are governed by a critical phenomenon due to the formation of a phase network above a critical blend ratio. As a result, a strongly nonlinear dependence of the glass transition maxima of the loss modulus on the volume fraction of the phases is observed. By counting the elastically effective bonds of the phase network, the local strain amplitude is estimated by purely geometrical arguments. Based on a consideration of the phase network, the distribution of carbon black in the different phases of filled blends is estimated from the height of the local maxima of the loss modulus in the glass transition regime. Thereby, a linear increase of the maximum value of the loss modulus with rising carbon black concentration is exploited that relates the enhanced energy dissipation of filled rubbers to the internal friction of the filler particles. Results on EPDM/BR/N550 blends indicate that carbon black is preferably located in the BR phase. A somewhat higher concentration of carbon black in the SBR phase is found in the case of NR/SBR(40% Styrene)/N330 blends.
Surface Instabilities in Compressed or Bent Rubber Blocks
Authors: Gent A. N. , Cho I. S. 
Published: February 2011

Abstract
Biot carried out theoretical analyses of the critical strains at which surface instabilities would be encountered in large blocks of a neo-Hookean material subjected to different degrees of compression in two directions. Three special cases are reviewed here: simple compression in one direction, compression in one direction with the perpendicular direction constrained (pure shear), and equibiaxial compression. In all cases a surface instability is predicted to occur at a moderate compressive strain, ranging from about 33% to about 55%. Because unidirectional compression occurs on the inner surface of a rubber block subjected to simple bending, a similar surface instability would be expected at a critical degree of bending, when the surface compression is about 46%. Observations on bent rubber blocks are compared with this theoretical prediction. Sharp creases occurred on the inner surface at a critical degree of bending but the critical compressive strain there was only about 35% and the bending curvature was less than predicted, only about one-half as severe. The cause of this discrepancy is not known.
Elastic Instabilities of Inflated Rubber Shells
Authors: Gent A. N. 
Published: February 2011

Abstract
Using a simple constitutive law for elastic behavior that includes the feature of a maximum allowable strain, equations are derived for inflation pressure as a function of the amount of inflation for three rubber shells: a thin-walled spherical balloon, a small spherical cavity in a large rubber block, and a thin-walled cylindrical tube. The results are compared with those obtained using the neo-Hookean constitutive law. Uniform expansion is generally predicted to become unstable at a modest degree of inflation but the new relations give a second stable inflation state, in accord with experience.
New Polyolefin Elastomers Containing “Reactive” p-Methylstyrene Units: Preparation by Metallocene Catalysts
Authors: Chung T. C. , Lu H. L. , Hong S. 
Published: February 2011

Abstract
This paper summarizes the experimental results of three new polyolefin elastomers, i.e., poly(1-octene-co- p-methylstyrene (O-p-MS), poly(ethylene-ter-propylene-ter-p-methylstyrene) (EP-p-MS) and poly(ethylene-ter-1-octene-ter-p-methylstyrene) (EO-p-MS), containing “reactive” p-MS units. Both Ziegler-Natta and metallocene catalysts were used in studying co- and ter-polymerization reactions. In the copolymerization of 1-octene and p-MS, Ziegler-Natta catalyst TiCl3/AlEt3 exhibits higher catalyst reactivity to produce high molecular weight O-p-MS copolymers, containing up to 20 mol % p-MS. However, the copolymers show very broad composition and molecular weight distributions. On the other hand, two EP-p-MS and EO-p-MS terpolymers with narrow molecular weight and composition distributions were prepared by [C5Me4(SiMe2NtBu)]TiCl2 metallocene catalyst with constrained ligand geometry. The sharp glass transition temperature (Tg) with flat baseline in each differential scanning calorimetry (DSC) curve indicates homogeneous terpolymer microstructures. The Tg of EP-p-MS is very sensitive to the terpolymer composition (ethylene/propylene ratio and p-MS content). In the compositions with ideal ethylene/propylene ratio ∼ 55/45, the Tα is almost proportional to the content of p-MS. Only with the concentration of p-MS &lt; 2 mol %, does the EP-p-MS show alow Tg&lt;−45°C. On the other hand, the EO-p-MS system exhibits a low Tg&lt;−50°C in a wide range of copolymer compositions, even ones with relatively high p-MS contents (&lt; 7 mol %).
Cure and Mechanical Behavior of Rubber Compounds Containing Ground Vulcanizates: Part III. Tensile and Tear Strength
Authors: Gibala D. , Thomas D. , Hamed G. R. 
Published: February 2011

Abstract
A black-filled styrene-butadiene rubber (SBR) vulcanizate was ambiently ground, then used as an additive to the original, uncured compound. Sheets of the resulting composite (matrix/ground rubber particulate) were cured, and tensile and trouser tear strength determined. The composite had reduced tensile strength, but enhanced tear strength relative to the original vulcanizate. The contrasting behavior is attributed to the effects of sulfur migration into the particulate rubber and differences in the responses of a tensile and a tear testpiece to discontinuities. In brief, ground rubber acts as a stress-raising flaw in tensile testing, while promoting crack tip blunting and stick-slip behavior in trouser tearing.
Carbon Black Surface Characterization by TOF-SIMS and XPS
Authors: Bertrand P. , Weng L. T. 
Published: February 2011

Abstract
The functional groups present at the carbon black (CB) surface contribute, along with the surface microstructure, to the CB surface activity which is known to be an important parameter for the rubber reinforcing properties. A direct detection of the foreign elements (H, N, O, S, Cl, …) present at the CB surface can be achieved with surface analytical techniques such as Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and X-ray Photoelectron Spectoscopy (XPS). The combination of these two techniques is found to be very fruitful. Indeed, although the TOF-SIMS sensitivity is much higher than for XPS, allowing trace detection, this technique suffers from a lack of quantification which can be fulfilled by XPS. The chemical information on the functional groups obtained by both methods is complementary. In XPS, this information is deduced from the electron core level chemical shifts which are mainly influenced by the first neighboring atoms; whereas, in TOF-SIMS, the full molecular environment can be detected. Not only information on the surface groups, but also some structural information can be obtained. Indeed, the TOF-SIMS spectra of carbon black exhibit molecular ions which are characteristic of the surface aromaticity (graphene structure) and also specific clusters at high masses which seem to be related to the basic building block of carbon black particles.
The Role of Filler Networking in Dynamic Properties of Filled Rubber
Authors: Wang Meng-Jiao 
Published: February 2011

Abstract
Fillers, when added to polymer systems, are known to cause a considerable change in dynamic properties. For a given polymer and cure system, this paper discusses the impact of the filler network, both its strength and architecture, on the dynamic modulus and hysteresis during dynamic strain. It was found that the filler network can substantially increase the effective volume of the filler due to rubber trapped in the agglomerates, leading to high elastic modulus. The amount of trapped rubber was estimated according to Van der Poel theory. During cyclic strain, while the stable filler network can reduce the hysteresis of the filled rubber, the breakdown and reformation of the filler network would cause an additional energy dissipation resulting in higher hysteresis.
Compatibilization of Ionomeric Polyblends by Intermolecular Ionic Interactions
Authors: Antony Prince , De S. K. 
Published: February 2011

Abstract
Ionomeric polyblends based on the zinc salt of carboxylated nitrile rubber, abbreviated as Zn-XNBR, and the zinc salt of poly(ethylene-co-methacrylic acid), abbreviated as Zn-EMA, were prepared by melt blending technique. Zn-XNBR/Zn-EMA ionomeric polyblends, in the compositions ranging from 90/10 to 50/50, parts by weight, behave as ionic thermoplastic elastomers, and show synergism in physical properties. The synergism in physical properties is attributed to the formation of a technologically compatible polyblend, wherein intermolecular ionic interactions between the neat ionomers take part in the compatibilization mechanism. Dynamic mechanical thermal analyses show a high temperature transition, owing to the presence of ionic clusters in the neat ionomers and the ionomeric polyblends. The ionomeric polyblend exhibits higher physical properties and melt viscosity than the corresponding non-ionomeric polyblend.