bluuebunny/crossref_metadata_2025_split huggingface dataset:
Blends of Butyl and Bromobutyl Rubbers and Polystyrene—Polyisobutylene—Polystyrene (PS—PIB—PS) Block Copolymers with Improved Processability and Physical Properties
Authors: Puskas Judit E. , Kaszas Gabor 
Published: February 2011

Abstract
An investigation of the effects of polystyrene—polyisobutylene linear triblock and three-arm star block thermoplastic elastomers on the processability and properties of butyl and bromobutyl rubbers was undertaken. All properties improved, with the exception of bromobutyl adhesion, which remained acceptable. The green strength of raw polymer blends improved by 30–80% and 5–20% improvement was seen on the carbon black compounds. Die swell was reduced by as much as 60% for compounds containing a triarm-star block. Tear strength doubled and air permeability decreased (by about) 20–40%. Fatigue life improved dramatically (20-fold on 300% crack growth and 80-fold on 600% crack growth). The cured blends can be viewed as interpenetrating networks of the chemically crosslinked rubber and the physically crosslinked thermoplastic elastomers.
Adhesive and Cohesive Strength in Polyisoprene/Polychloroprene Blends
Authors: Kardan Mahmoud 
Published: February 2011

Abstract
This study concerns the use of polymer blends to produce advanced high performance adhesive systems based on material economics as well as to gain knowledge about the thermodynamics of multi-component adhesive systems. In the adhesive industry, blends of natural rubber (polyisoprene) and polychloroprene are used not only to lower cost, but also to provide certain properties, which are not obtainable with either elastomer alone. This paper investigates the contribution of each elastomer in the blend to the cohesive and adhesive strength and durability of the system. Composites of synthetic cis-1,4-polyisoprene with different types of polychloroprene with modified structures have been prepared by mill compounding. Infrared spectra obtained for these composites when coated on metallic surface have been extremely useful in the elucidation of the molecular orientation and conformational changes associated with these polymers. Each sample has been laminated between metallic substrates and for each lamination; the lap shear has been measured. The measured lap shears have been correlated with the structural changes associated with polymer—polymer interactions, detected by reflection infrared spectroscopy. These results could have a significant bearing on the mechanism of the strength development in rubber blends for use in adhesive and sealant systems.
Synthesis and Use of Colloidal Silica for Reinforcement in Silicone Elastomers
Authors: Kwan Kermit S. , Harrington Daniel A. , Moore Patricia A. , Hahn James R. , Degroot Jon V. , Burns Gary T. 
Published: February 2011

Abstract
Aqueous suspensions of colloidal silicas are readily silylated with either chlorosilanes or disiloxanes in the presence of acid and isopropyl alcohol without aggregation of the silica particle. By using a mixture of chlorosilanes or disiloxanes, spherical nanoparticles with controlled functionality can be made and transferred to an organic phase to provide stable, water free suspensions. The hydrophobic silica particles readily disperse into silicone polymers. At sufficient loading levels, they provide mechanical reinforcement comparable to traditional fillers but with improved clarity and lower viscosities. Modulus and durometer control in the cured elastomer is possible by varying the ratio of the vinyl concentration on the filler particle to the vinyl concentration in the polymer phase.
Surface Chlorination of Ground Rubber Tire and its Characterization
Authors: Naskar Amit Kumar , De S. K. , Bhowmick Anil K. 
Published: February 2011

Abstract
Ground rubber tire (GRT) powders were chlorinated by trichloroisocyanuric acid (TCLCA). GRT powders of different chlorination levels were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDAX), attenuated total reflection infrared (ATR-IR) spectroscopy, thermal, dielectric, and stress—strain properties on molded GRT specimens. Surface energy of the powders was estimated. Dynamic mechanical thermal analysis of molded GRT specimen reveals a biphasic structure. Plasticized poly(vinyl chloride) (PVC) compound, when blended with chlorinated GRT, shows improved physical properties in comparison to non-chlorinated GRT.
A New Class of Ethylene—Propylene—Diene Terpolymers Produced from Constrained Geometry Metallocene Catalysts
Authors: Walton Kim L. , Hughes Morgan M. , Parikh Deepak R. 
Published: February 2011

Abstract
Until recently, ethylene/propylene/diene (EPDM) terpolymers have been manufactured exclusively using vanadium based Ziegler—Natta catalyst systems. The vanadium based catalysts are known to have both product and process limitations. These limitations are due to a complex combination of factors including monomer reactivity, catalyst activity, reactor temperatures and pressures. Single-site metallocene constrained geometry catalyst (CGC) technology enables the manufacture of EPDM terpolymers at higher reactor temperature and catalyst efficiency than standard Ziegler—Natta catalyst systems. The unique combination of monomer, catalyst and process technology enables the manufacture of highly crystalline EPDMs having ethylene contents over 90 wt %. This study investigated these new highly crystalline EPDM terpolymers and their differentiation from commercially available EPDMs. The results indicated that these new EPDMs had very high green strength and barrier properties, yet could be cured by conventional vulcanization techniques. The cure response of these EPDMs to either peroxide or sulfur increased with increasing ethylene content. Sulfur cured vulcanizates had much higher tensile strength than peroxide cured vulcanizates. These new EPDMs demonstrated utility as additives to enhance the abrasion, hot tear, and tensile properties of natural rubber compounds. Sponge compounds, having the unique combination of polyethylene physical properties and the utility of sulfur vulcanization were developed from these new polymers.
Mooney Viscosity Stability and Polymer Filler Interactions in Silica Filled Rubbers
Authors: Lin Chenchy , Hergenrother William L. , Hilton Ashley S. 
Published: February 2011

Abstract
The change in Mooney viscosity (ML1+4) with aging was followed for silica filled compounds containing various silanes and polar additives. Several mechanisms for the aging stability are postulated and evaluated through experimentation. The type of silane or polar additive used can cause the ML1+4 to increase or even decrease during aging. When bis(triethoxy silanes) are used in silica filled rubbers, the ML1+4 growth during aging is caused by hydrolysis. Silica-silica bridging was found to be responsible for the ML1+4 growth in rubber compounds containing a more thermally stable polysulfide or a sulfur-free bis(triethoxy silane). When the bis(triethoxy silane) is bis(3-triethoxysilylpropyl) tetrasulfide (TESPT), a fraction of TESPT is attached to the unsaturated rubber to give polymer-silica attachments. These attachments further enhance the hydrolytic ML1+4 increase during aging. Chemical coating of the silica with a monofunctional silane or a physical coating with a trialkyl amine compound effectively stops the ML1+4 increase upon aging. The prevention of ML1+4 growth is so efficient that a reduction in the ML1+4 can be realized by absorption of ambient moisture. The extent of ML1+4 reduction caused by moisture depends on the degree of hydrophobation of the coated silicas. Hydrolytic stability was also studied with an amine or a sugar fatty acid ester that formed either strong or weak polar associations to the silica.
Rheological Model of Uncured Silica-Filled Tire Compounds: Application to a Simple Shear Start-Up Flow
Authors: Schaal Stéphane , Coran Aubert Y. 
Published: February 2011

Abstract
A constitutive equation that describes the rheological behavior of highly filled uncured tire compounds was developed and applied to the special case of a low shear rate start-up flow. Start-up flow rheology is related to processability. This model is consistent with the interpretation, that the peak stress in a start-up flow experiment (Mooney peak) performed at low strain rates may be described as a yield stress. As the system is stretched, more and more structural members rupture according to their respective ultimate strains described by a Weibull distribution function. Moreover, the model describes the effects of storage time on start-up flow rheology through a kinetic analysis and relates the changes in rheology to the formation of bound rubber during storage.
Simulation and Verification for Sulfur Accelerated Vulcanization of Gum Natural Rubber Compound
Authors: Fan Ru-liang , Zhang Yong , Huang Chen , Gong Peng , Zhang Yin-xi 
Published: February 2011

Abstract
A simplified and realistic kinetic scheme was proposed for the cure reversion mechanism of accelerated sulfur vulcanization for gum natural rubber (NR) compounds. The vulcametric curves at different temperatures were simulated from curing to overcuring periods by using a kinetic approach. The different rate constants and activation energies were calculated from the simulation process. The simulated results showed a good agreement with isothermal vulcametric data over a wide range of temperatures and showed that the relationships between the rate constants and the cure temperatures were in accordance with the Arrhenius Equation. The activation energies (Ea1, Ea2, and Ea3) of the formation, desulfurization and decomposition of polysulfidic crosslink obtained from Arrhenius plots were 79.5,102.6 and 138.8 kJ/mol, respectively. The experimentally measured crosslink densities determined by using swelling equilibrium and chemical probe techniques agreed with the simulated vulcametric curves to some extent.
Effect of Bis (Diisopropyl) Thiophosphoryl Disulfide on the Co-Vulcanization of Carboxylic-Acrylonitrile-Butadiene Rubber and Ethylene-Propylene-Diene Rubber Blends
Authors: Naskar Nityananda , Debnath Subhas Chandra , Basu Dipak Kumar 
Published: February 2011

Abstract
The objective of the work is to prepare compatible, coherent and technologically feasible blends comprising non-polar EPDM rubber and polar carboxylic-acrylonitrile-butadiene rubber (XNBR). Using an efficient sulfur vulcanization system containing bis(diisopropyl) thiophosphoryl disulfide (DIPDIS), a coupling agent cum accelerator, EPDM-XNBR blend has been co-vulcanized. The blend vulcanizates thus produced exhibit substantially enhanced physical properties which are superior to those of either component. The compatibility of the rubber blends as judged by SEM micrographs can further be improved through a two-stage vulcanization process which promotes interphase crosslinking between the polymer phases. The interphase crosslinking was recognized from swelling experiments. The study of the blends containing carbon black reveals a profound increase in physical properties of the vulcanizates as compared to those of gum vulcanizates. The SEM micrographs of the blend vulcanizates both in one-stage and two-stage distinctly indicate the blend morphology, which accounts for the significant improvement in physical properties of EPDM-XNBR blends through in situ reactive compatibilization. A reaction scheme for the interphase crosslinking has been proposed for the co-curing of EPDM-XNBR blend.
Effect of Crosslink Density on Cut Growth in Gum Natural Rubber Vulcanizates
Authors: Hamed G. R. , Rattanasom N. 
Published: February 2011

Abstract
Conventional sulfur-cured, gum natural rubber vulcanizates of various crosslink densities were prepared. Dumbbell test pieces with and without edge precuts were tested in uniaxial tension. Relative strengths of the different vulcanizates depended on cut size. Lightly crosslinked specimens exhibited an abrupt drop in strength at a critical cut size, ccr, which became smaller as crosslink density increased because of reduced strain crystallizability. At all cut depths, crack growth was simply perpendicular to the loading direction and crack surfaces were smooth. A moderately crosslinked composition exhibited crack deviation prior to rupture. This was associated with an unusual increase in strength with increasing cut size. Densely crosslinked networks exhibited lateral fracture, like the lightly crosslinked gums, but produced a jagged crack contour path reflective of a rough fracture surface. Moreover, for the highly crosslinked samples, a critical cut size was not found. Rather, log-log plots of strength versus cut depth were linear and had slopes slightly greater than minus one-half.
Influence of Material Non Homogeneity on the Shearing Response of a Neo Hookean Slab
Authors: Bilgili Ecevit , Bernstein Barry , Arastoopour Hamid 
Published: February 2011

Abstract
Vulcanized rubber components possess material non-homogeneities due to either non-uniform vulcanization during their fabrication or attack of thermal and oxidative environments during their service life. The primary objective of this paper is to theoretically investigate the effect of a material non-homogeneity on the shearing response of an isotropic, incompressible neo-Hookean slab. The non-homogeneity considered in the slab is the spatially varying shear modulus that is approximately described by a spatial-distribution function. A parabolic and a boundary layer-like spatial-distribution function are assumed; then exact solutions for the stress—strain fields in the slab are obtained by solving the linear momentum balance equations based on a postulated inhomogeneous shearing deformation. Our theoretical results show that the shear strain is more inhomogeneous and localized for the slabs with a greater degree of spatial non-homogeneity. In the non-homogeneous slabs, we have also determined the existence of a uniform shear stress and an inhomogeneous first normal-stress difference whose variation is similar to that of the shear strain. The implications of these results are considered in terms of the fabrication, performance and mechanical characterization of the rubber-elastic materials.
Influence of Different Silanes on the Reinforcement of Silica-Filled Rubber Compounds
Authors: Luginsland Hans-Detlef , Fröhlich Joachim , Wehmeier André 
Published: February 2011

Abstract
The silane modification of precipitated silica for rubber applications is state-of-the-art. Usually, bifunctional silanes are used to provide a silica-to-rubber coupling. In this paper, the general effect of the silane modification on the Payne-effect of silica-filled compounds (S-SBR/BR) is investigated by applying the Rubber Process Analyzer (RPA). For this purpose, the amount as well as the type of silane have been varied. The alkyl chain length of monofunctional silanes determines their hydrophobation efficiency and therefore influences the degree of the silica network, whereas bifunctional silanes also contribute to the crosslinking and build up an in-rubber structure. The degree of the filler network is not only determined by the kind of silica modification, but also by the reinforcement behavior of the silica, mainly characterized by the CTAB surface area. The findings of this study give a better insight into the reinforcement of silica-filled rubber compounds and their dynamic properties.
Modification of Dual Phase Filler by Electron Beam Irradiation: Physical Characterization
Authors: Shanmugharaj A. M. , Bhowmick Anil K. 
Published: February 2011

Abstract
Electron beam modification of carbon black (N220) and carbon-silica dual phase filler affects the microstructure of carbon black. This is confirmed from X-ray diffraction studies. The scanning electron microscopy /energy dispersive X-ray analysis reveals surface oxidation, which is further corroborated from nitrogen and iodine adsorptions. Transmission electron microscopy studies show the aggregation of fillers upon electron beam irradiation. Linear fractal dimension calculated by image analysis increases upon irradiation, due to the formation of filler aggregates.
Interaction Between Rubber and Carbon Black Studied by ToF-SIMS
Authors: Bertrand P. , Weng L.-T. , Lauer W. , Zimmer R. 
Published: February 2011

Abstract
In order to study the rubber—carbon black filler interaction, different styrene-butadiene rubbers were adsorbed from solution on carbon black. Afterwards, the samples were washed to keep only the thin layer of bound rubber. The surface of these samples was characterized by ToF-SIMS. It was found that the carbon black surface was completely covered by the polymer, except for pure 1,4-polybutadiene where a non-uniform adsorption was seen. Moreover, the ToF-SIMS data showed that the parameters related to the polymer aromaticity and unsaturation decreased after adsorption. These results indicated a change in polymer chain conformation at the surface upon adsorption on carbon black. This was explained by a preferential interaction between phenyl (and in a weaker manner, 1,2-vinyl) groups with the carbon black surface. Indeed, when these groups tend to orientate toward the filler surface, their surface concentration seen by ToF-SIMS is expected to decrease.
Effect of Gel on the Green Strength of Natural Rubber
Authors: Kawahara Seiichi , Isono Yoshinobu , Sakdapipanich Jitladda T. , Tanaka Yasuyuki , Aik-Hwee Eng 
Published: February 2011

Abstract
The outstanding properties of natural rubber, e.g., green strength and rapid crystallization, were attributed to the chemical branching that formed at both chain ends of the rubber molecule during the preservation of the latex in the presence of ammonia. The gel content of natural rubbers from various clonal origins increased during the preservation, but decreased after deproteinization of the aged latex. The crystallization of acetone-extracted rubber was slightly suppressed as the gel content increased. The increase in green strength during the preservation was studied in connection with the gel content and degree of branching of the rubber.
Dynamic Stiffness Matrix of a Long Rubber Bush Mounting
Authors: Kari L. 
Published: February 2011

Abstract
The complete blocked dynamic stiffness matrix of a long rubber bush mounting of particular interest for noise abatement is examined by an analytical model, where influences of audible frequencies, material properties, bush mounting length, and radius, are investigated. The model is based on the dispersion relation for an infinite, thick-walled cylinder with arbitrary boundary conditions at the radial inner and outer surfaces; yielding the sought stiffness matrix, including axial, torsional, radial, and tilting stiffness. A nearly incompressible material model is adopted, being elastic in dilatation while displaying viscoelasticity in deviation. The applied deviatoric Mittag-Leffler relaxation function is based on a fractional standard linear solid, the main advantage being the minimum number of parameters required to successfully model the rubber properties over a broad structure-borne sound frequency domain. The dynamic stiffness components display a strong frequency dependence at audible frequencies, resulting in acoustical resonance phenomena, such as stiffness peaks and troughs. The low-frequency stiffness asymptotes of the presented model are shown to agree with those of static theories.
Specific Influences in the Polymerization of Dienes. Chemical Factors Influencing the Homogeneity of Synthetic Rubbers during Production
Authors: Penn William S. 
Published: February 2011

Abstract
At the present time, when so much synthetic rubber is being produced, the question of the polymerization of dienes is most important. Many thousands of tons of GR-S and related rubbers are being made by this means, and yet the process is only very imperfectly understood. Polymerization is still an uncontrolled reaction, although much work has been done in an attempt to overcome the deficiencies. The troubles are caused by the fact that the dienes do not polymerize in a regular way, because of the formation of branch chains and cross-linkages, which are a direct result of these branch chains. These irregularities must be controlled before satisfactory products can be obtained, and the present paper is written to correlate isolated evidence and present fresh material so that the processes involved during polymerization may be more perfectly understood and possibly controlled. It is natural in the first instance to examine natural rubber to see if any indication of the lines to follow can be obtained. Unfortunately, however, even natural rubber is not perfect, and from various sources of evidence it has been shown that branching does occur in the isoprene chains. This branching is, however, different from that in synthetics, and is quite regular. As will be seen shortly, it is difficult on chemical or physico-chemical grounds to see why this should be so, as the only directive group in the isoprene unit is the methyl side-group. It seems logical to conclude that natural rubber is not formed by a polymerization process, but that carbon and hydrogen atoms combine in such a way that they form directly a natural rubber-molecule.
The Polymerization of Methacrylonitrile. Polymethacrylonitrile
Authors: Kern Werner , Fernow Helmut 
Published: February 2011

Abstract
As the starting point for the preparation of methaerylonitrile, acetonecyanohydrin (α-hydroxybutyronitrile) was chosen because of its ready availability. β-Hydroxybutyronitrile should likewise be well suited for the purpose, but, because of the difficulties involved in its preparation, it was not utilized in the work. The removal of water can be accomplished in various ways. (1) Phosphorus pentoxide does not give such smooth results as it does with ethyleneeyanohydrin, but the reaction can be carried out successfully by centrifuging and the addition of quinoline. Under the same conditions acetaldehydeeyanohydrine (lactonitrile) yields no acrylonitrile. (2) The thermal decomposition of acylated hydroxy-acid derivatives can be applied to acetonecyanohydrin, but this method of preparation is difficult to carry out on a laboratory scale. (3) Removal of water can be carried out very smoothly with thionyl chloride. In addition to methacrylonitrile, α-chloroisobutyronitrile is formed, and from the latter more methacrylonitrile can be obtained by scission of hydrogen chloride. In this procedure, it is highly important to use pure raw materials, especially thionyl chloride, for with pure compounds the yields are higher. It is likewise advantageous to use a slight excess of thionyl chloride.