bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gel Formation in Natural Rubber Latex: 2. Effect of Magnesium Ion
Authors: Tarachiwin L. , Sakdapipanich J. T. , Tanaka Y. 
Published: February 2011

Abstract
The effect of Mg2+ ions on the gel formation in fresh and commercial high ammonia natural rubber latices (FL-latex and commercial HA-latex) was analyzed from the gel content and 2+ content after treatment with (NH4)2SO4. The gel content of rubber from commercial HA-latex decreased significantly after (NH4)2SO4 treatment comparable to that of FL-latex. Long-storage commercial HA-latex containing 50% gel fraction showed no decrease in 2+ content after (NH4)2SO4 treatment. This gel fraction was not solubilized in toluene by the treatment of a proteolytic enzyme in latex or ethanol/toluene mixed solvent extraction of rubber. The 2+ content of rubber in long-storage commercial HA-latex, 0.005% (w/w rubber), decreased after treatment with (NH4)2SO4, while the same treatment showed little change on FL-latex, 0.035%. The toluene soluble fraction of these latices showed a decrease in the Mn value with an increase in the (NH4)2SO4 concentration. The gel content of FL- and HA-lattices increased with an increasing storage period in the presence and absence of (NH4)2SO4. The initial rate of increase in the gel content was slow in the case of FL-latex. These findings indicate that the gel fraction in HA-latex is partly formed by ionic crosslinks caused by 2+ ions. Whereas, the gel phase in long-storage commercial HA-latex is presumed to be a hard gel predominantly formed by covalent bonding.
Crack Growth in Twisted Rubber Disks. Part 3. Effects of Crack Depth and Location
Authors: Gent A. N. , Yeoh O. H. 
Published: February 2011

Abstract
A simple analysis of the fracture energy for a shallow ring crack in a twisted rubber disk is presented and compared to a linear fracture mechanics solution for a similar crack in an infinitely long cylinder. The analysis predicts that the fracture energy increases linearly with crack depth. Since a previous analysis shows that the fracture energy subsequently decreases with crack depth when the crack is deep, it follows that the fracture energy passes through a peak as it transitions from shallow crack to deep crack behavior. The transition occurs when the crack depth becomes comparable to a fraction of the disk height. The analysis is supported by the results of finite element analysis. In addition, the effects of disk size, crack location (in the middle of the cylinder vs. at the bonded ends) and material properties are also considered.
Ground Tire Rubber (GTR) Reclamation: Virgin Rubber / Reclaimed GTR (RE)Vulcanizates
Authors: Grigoryeva O. , Fainleib A. , Starostenko O. , Danilenko I. , Kozak N. , Dudarenko G. 
Published: February 2011

Abstract
Thermochemically partially devulcanized ground tire rubber (GTRD) was revulcanized in compositions with different virgin rubbers. Two different devulcanizing groups (mixture of softeners) with and without processing oil have been used for GTR treatment. As virgin rubbers methylstyrene/butadiene (SBR), isoprene (IR) and butadiene (BR) rubbers or their combinations were selected. They were cured by using sulfur, tetramethyl thiuram disulfide (TMTD) or peroxide based vulcanizing systems. The Rubber/GTRD (re)vulcanizates with the GTRD content from 20 to 80 wt. % have been prepared and studied. Vulcanization by sulfur system was found as preferable for IR/GTRD formulations. The best properties for BR/GTRD and SBR/GTRD vulcanizates were reached with the vulcanization system based on TMTD. The co-curing in the interphase between the GTRD particles and the surrounding rubber matrix improves the mechanical properties of (re)vulcanizates obtained. The reclaimed GTRD studied has been used successfully in standard formulations for tires instead of the part of virgin rubbers.
Online Characterization of the Effect of Mixing Parameters on Carbon Black Dispersion in Rubber Compounds Using Electrical Conductivity
Authors: Le H. H. , Ilisch S. , Jakob B. , Radusch H.-J. 
Published: February 2011

Abstract
The influences of mixing parameters on the carbon black dispersion can be characterized using the electrical conductivity online measured from internal mixer. As a measure for monitoring the development of carbon black dispersion, a normalized conductivity with regard to the conductivity measured at the BIT (black incorporation time) has been suggested. It is observed that in spite of different mixing parameters, the mixtures possessing the same normalized conductivity factor K/KBIT deliver the same carbon black dispersion and the same mechanical properties. Based on normalized conductivity, a deeper insight into the mixing kinetics can be provided to find an optimal mixing regime.
FTIR Spectroscopic Studies on Curing of Brominated Poly(Isobutylene-co-4-Methylstyrene)
Authors: Xie Donghang , Wang Hsien C. 
Published: February 2011

Abstract
The curing of brominated poly(isobutylene-co-4-methylstyrene) or BIMS with ZnO/HSt, ZnO/Zn(St)2 or Zn(St)2 was investigated using FTIR spectroscopy. Changes of carbonyl absorption were monitored by FTIR during the course of curing, which revealed a four-step curing process: 1) formation of zinc salts, 2) esterification to generate Zn-containing Lewis-acid catalysts, 3) Friedel-Crafts alkylation, and 4) post cure. It was found that for the ZnO/HSt system, the ZnO concentration had to be high enough to meet the ZnO/Br molar ratio of 0.9 for complete conversion of curing functionalities. HSt was an effective accelerator, which reduces the induction time and increases the curing rate. HSt of 2 to 3 phr was recommended to achieve optimum acceleration results. Over use of HSt would lead to dramatic reduction of crosslinking density, due to the fact that significant amounts of curing functionalities were consumed to form stearate esters instead of crosslinks. The curing with ZnO/Zn(St)2 was similar to the ZnO/HSt system but faster due to the fact that zinc salt was directly added. Zn(St)2 alone was effective to initiate a cure, but the reversion of curing was observed at high concentrations, probably due to the presence of large amount of acids, such as HSt and HBr both of which were generated during curing, and the stearate esters. Addition of ZnO eliminates the reversion through neutralization of the acids.
Tear Strength of Black-Filled Natural Rubber Crosslinked via Conventional and Efficient Sulfur Cures
Authors: Hamed G. R. 
Published: February 2011

Abstract
Two common types of sulfur cures for diene elastomers are so-called conventional and efficient systems. It is widely thought that the former results in higher tear strength, when vulcanizates are compared at the same crosslink density. However, using data taken from the literature, this behavior is shown to occur at higher crosslink density, while the opposite is true at lower crosslink density.
A Simple Model for Predicting Heat Aging of EPDM Rubber
Authors: Paeglis Arnis U. 
Published: February 2011

Abstract
Heat aging stability is a hallmark of EPDM rubber and a requirement for use in automotive, roofing and other applications. Retention of physical properties after accelerated heat aging is a typical specification for such long-term uses. This paper examines the utility of such tests in predicting results over a range of temperatures, 116 °C, 125 °C, 135 °C and 150 °C, in some cases for as long as 365 days.
A simple empirical model was developed to predict the retention of physical properties using fractional strain energy, that is, the ratio of the aged to unaged products of tensile strength and elongation at break. Characteristic rates, an Arrhenius rate relationship and activation energies were determined. This model provides a basis to predict physical property changes over a wide range of temperatures and times, as well as for considerations of equivalent heat aging tests and use in different applications.
Adhesion Strength Evaluation via Constrained Blister Test I. SIBS / Polystyrene and Polypropylene
Authors: Mousa A. M. , Mekewi M. A. , El-Mosallamy E. S. H. , Baer E. 
Published: February 2011

Abstract
Adhesion of Styrene-Isobutylene-Styrene (SIBS) triblock copolymers to polystyrene and polypropylene was investigated at controlled ratios and molecular weights of the SIBS's polystyrene. Comparative studies of the cohesive and adhesive strengths were carried out using a carefully designed system based on monitoring a constrained blister growth. The acquired data was simulated mathematically to express adhesion main parameters of the energy of interfacial adhesion (γ) and dissipation coefficient (b). Polystyrene content of 30–40% in the SIBS exhibited maximum interfacial adhesion energy (γ) and, consequently, the highest adhesion strength compared to other SIBS samples of other polystyrene ratios. ATR-FTIR spectroscopic analysis and scanning electron microscopy (SEM) were carried out on both the substrate and the film surfaces before adhesion and after failure to assist understanding the failure process. Interpretation of SEM microphotographs and the ATR-FTIR confirmed the process to be adhesion in nature rather than cohesion.
Synthesis of Cyclic Polysulfides and their Properties as Curing Agents
Authors: Choi Wonmun , Matsumura Tomoyuki 
Published: February 2011

Abstract
The reactions of dichloroalkanes and sodium tetra-sulfide (Na2S4) were carried out in a mixture of water and toluene to produce corresponding cyclic polysulfides and polysulfide polymer. The low molecular weights of cyclic sulfides were obtained by the reaction at 90 °C, while the high molecular weight of polysulfide polymer was obtained by the reaction at 50 °C. GPC chromatograms and Mass spectra revealed that the structures of cyclic polysulfide were 1:1, 2:2, and 3:3 adducts of dichloroalkane and sodium tetra-sulfide. The mechanical properties of vulcanized NR at 148 °C with cyclic sulfides were similar to that with sulfur. However, both tensile strength and elongation at break of vulcanized NR at 170 °C with cyclic sulfides are much higher than that with sulfur. The aging properties of vulcanized NR at 148 °C or 170 °C with cyclic polysulfides indicate better stability.
Factors that Affect the Fatigue Life of Rubber: A Literature Survey
Authors: Mars W. V. , Fatemi A. 
Published: February 2011

Abstract
Many factors are known to influence the mechanical fatigue life of rubber components. Four major categories of factors are reviewed here: the effects of mechanical loading history, environmental effects, effects of rubber formulation, and effects due to dissipative aspects of the constitutive response of rubber. For each category, primary factors are described, and existing literature is presented and reviewed. Rubber's fatigue behavior is extremely sensitive to both the maximum and minimum cyclic load limits. Other aspects of the mechanical load history are also discussed, including the effects of static loaded periods (“annealing”), load sequence, multiaxiality, frequency, and loading waveform. Environmental factors can affect both the short and long term fatigue behavior of rubber. The effects of temperature, oxygen, ozone, and static electrical charges are reviewed. A great range of behavior is available by proper manipulation of formulation and processing variables. Effects of elastomer type, filler type and volume fraction, antidegradants, curatives, and vulcanization are discussed. The role of dissipative constitutive behavior in the improvement of fatigue properties of rubber is also reviewed. Four distinct dissipative mechanisms are identified, and their effects on fatigue behavior are described.
Addressing Durability of Rubber Compounds
Authors: Huntink N. M. , Datta R. N. , Noordermeer J. W. M. 
Published: February 2011

Abstract
The developments on long-term protection of rubber against aerobic aging are reviewed. Although conventional antidegradants such as N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) are still the most widely used antidegradants in rubber, there is a trend and demand for longer-lasting and non-staining products. The relatively low molecular weight (MW) antioxidants have undergone an evolutionary change towards higher molecular weight products with the objective to achieve permanence in the rubber polymer, without loss of antioxidant activity. In the last two decades, several approaches have been evaluated in order to achieve this objective: attachment of hydrocarbon chains to conventional antioxidants in order to increase the MW and compatibility with the rubber matrix; oligomeric or polymeric antioxidants; and polymer bound or covulcanizable antioxidants. The disadvantage of polymer bound antioxidants was tackled by grafting antioxidants on low MW polysiloxanes, which are compatible with many polymers. New developments on antiozonants have focused on non-staining and slow migrating products, which last longer in rubber compounds. Several new types of non-staining antiozonants have been developed, but none of them appeared to be as efficient as the chemically substituted p-phenylenediamines. The most prevalent approach to achieve non-staining ozone protection of rubber compounds is to use an inherently ozone-resistant, saturated backbone polymer in blends with a diene rubber. The disadvantage of this approach, however, is the complicated mixing procedure needed to ensure that the required small polymer domain size is achieved.
Metallocene Catalyzed Ethylene/Alpha Olefin Copolymers Used in Thermoplastic Elastomers
Authors: Walton Kim L. 
Published: February 2011

Abstract
Thermoplastic elastomers (TPEs) continue to be a focus of significant research as well as commercial development in the rubber industry since their origin over forty years ago. A wide variety of TPEs exist today. Ethylene copolymer and terpolymer based elastomers continue to play an increasing role in this arena. New ethylene copolymers and terpolymers, based upon metallocene catalysis, have further diversified the TPE portfolio. Compounders are now using these new elastomers as modifiers for existing TPEs as well as the principle elastomer in new TPEs
Influence of Electron Beam Irradiation as One of the Mixed Crosslinking Systems on the Structure and Properties of Nitrile Rubber
Authors: Vijayabaskar V. , Costa Francis Rene , Bhowmick Anil K. 
Published: February 2011

Abstract
The influence of electron beam on the nitrile rubber vulcanizates at varying levels of sulfur is reported. A higher crosslinking density, reduced elongation at break, increased modulus and tensile strength have been observed for the irradiated rubbers, as compared to the control rubber vulcanizates. The vulcanizate containing higher amount of sulfur, tends to form more crosslinkages on impinging with electron beam. This behavior is explained by the formation of monosulphidic linkages and is ascertained with the help of IR analysis (ATR mode), solid-state NMR analysis and chemical probe treatments of the irradiated vulcanizates. The implausible nature of these mixed crosslinking systems with electron beam as an additional crosslinker is explained with a kinetic model using steady state principle. A mechanistic path is suggested for explaining the structural changes on irradiation of these vulcanizates, which is supported by this model.
Model Reaction of Polysulfide with Olefin
Authors: Hergenrother William L. , Hilton Ashley S. , Lin Chenchy J. 
Published: February 2011

Abstract
A model polysulfide, t-butyl polysulfide (TBPS) and an olefin, cyclododecene (CDD), were used to study the reactivity of polysulfanes in silica filled rubbers. The TBPS has a similar sulfur rank and distribution as bis (3-triethoxysilylpropyl) tetrasulfide (TESPT) without the complication of reactivity of the triethoxysilyl group that would cause a loss of soluble components of the reactants and products by hydrolytic coupling. Thermal reaction between the polysulfide and olefin was investigated by following the TBPS loss in the CDD solution at 171 °C as a function of time. The loss of TBPS and the formation of reaction products during heating were followed, identified and quantified using HPLC. These include attachment of t-butyl sulfide group from the TBPS to CDD, coupling between CDD, and redistribution of the sulfur rank. It was found that after six minutes, less than 2 weight % of the sulfur in the TBPS was utilized to couple CDD molecules. Since these thermal conditions are more severe than what a rubber compound is normally subjected to, this sulfur coupling would not be expected to give a vulcanization problem during mixing. The model reaction was also followed in the presence of added peroxide or typical vulcanization ingredients. The strongest catalytic effect was seen with N-cyclohexyl-2-benzothiazolesulfenamide and zinc oxide.
Investigation of Mechanical and Fracture Mechanical Properties of Elastomers Filled with Precipitated Silica and Nanofillers Based upon Layered Silicates
Authors: Reincke Katrin , Grellmann Wolfgang , Heinrich Gert 
Published: February 2011

Abstract
The aim of this paper is to show possibilities of experimental methods of polymer diagnostics and fracture mechanics for quantitative characterization of crack initiation and propagation properties of elastomeric materials. At first, a general overview of methods of technical fracture mechanics is given. This is followed by a short discussion of some possibilities for determination of tearing energy T for elastomers. In the main part, results of various mechanical and fracture mechanics experiments on filled natural rubber vulcanizates are shown. The vulcanizates were filled with different contents (5–70 phr) of two filler types. The fillers were precipitated silica and an organic-modified nano-disperse layered silicate. Th aim of the experiments was to prove possibilities of several fracture mechanics testing methods for quantifying the influence of the filler content, filler type and additionally the specimen direction on the deformation and fracture behavior. Tear-analyzer results were used to assess the crack propagation behavior under fatigue-like loading conditions. Furthermore, instrumented tensile-impact tests were performed for the characterization of the crack resistance of the materials under impact-like loading conditions. To obtain information about the initiation and propagation of a stable crack, a quasi-static fracture mechanics test was applied, and crack resistance curves were recorded. Here, specimens with various thicknesses were investigated. Additionally, conventional tear tests were done and the results were compared to that of the fracture mechanics test. Generally, it was found that all methods are useful for the description of the fracture properties. Furthermore, the fracture behavior is influenced positively especially by high filler contents. Strong differences of several parameters were found depending on the filler type. Another important result is that again differences were found between the crack initiation and propagation behavior.
Carbon Black Dispersion Measurement in Rubber Vulcanizates via Interferometric Microscopy
Authors: Smith Archie P. , Aybar Toni L. , Magee Ricky W. , Herd Charles R. 
Published: February 2011

Abstract
A new method for characterizing the carbon black dispersion in rubber compounds is introduced. This technique is based on interferometric microscopy (IFM) and utilizes the interference fringes between in-phase light beams reflected from the rubber sample and a smooth reference surface to measure the three-dimensional surface topography. The peaks and valleys present on the fresh-cut surface are representative of the carbon black agglomerates and are used to characterize the dispersion. A series of samples with different base rubbers and varying dispersion levels were created and characterized by both light microscopy and IFM. These results were used to generate a universal dispersion index based on the IFM data that correlates well with the LM dispersion index values. In addition, three-dimensional peak statistics were obtained from the IFM data and used to provide additional information about the carbon black agglomerate distribution. This data can be used for a more complete understanding of the compound behavior as a function of the carbon black dispersion and agglomerate distribution.
A Comparison of the Hart-Smith Model with Arruda-Boyce and Gent Formulations for Rubber Elasticity
Authors: Chagnon G. , Marckmann G. , Verron E. 
Published: February 2011

Abstract
The present paper demonstrates that the Hart-Smith constitutive model and the more recent Arruda and Boyce eight chains and Gent constitutive models are closely related. The ability of these three models to predict both small and large strain responses of rubbers is highlighted and equations that relate their material parameters are established.
A Two-Step Emulsion Polymerization Process Catalyzed by an Organic Diperoxide
Authors: Bauer R. F. 
Published: February 2011

Abstract
An emulsion polymerization process is described which consists of consecutively polymerizing at least two olefinic monomers using an organic diperoxide with two independently functioning peroxy groups, namely 2,5-dimethyl-2-t-butylperoxy-5-hydroxy hexane.
In the first polymerization step, the hydroperoxide group is activated by a redox reaction at low temperatures without decomposing the t-butyl peroxide portion of the initiator molecule. After charging fresh monomer, the t-butyl peroxide can then be thermally activated to initiate a second-stage polymerization reaction.
This polymerization process employs conventional emulsion polymerization technology. It yields polymeric product with unique physical properties. Polymers with butadiene monomer in the first polymerization step, followed by styrene polymerization in the second step, resemble SBS tri-block polymers. They are thermoplastic, highly resilient and of good strength at high ultimate elongations. The consecutive polymerization of butadiene and acrylonitrile yields elastomers with a superior balance of low-temperature flexibility and resistance to swelling in organic solvents, when compared with random NBR copolymers of equivalent chemical composition. Combinations of butadiene and styrene in the first polymerization stage followed by styrene/acrylonitrile polymerization in the second, yield transparent ABS polymers with superior low-temperature impact resistance.
Reference is also made to the polymerization of additional vinyl monomers.
Correlation Between Road Wear of Tires and Computer Road Wear Simulation Using Laboratory Abrasion Data
Authors: Grosch K. A. 
Published: February 2011

Abstract
Any laboratory abrasion method has to take account of the well known fact that the ranking and wear rating of tire tread compounds depend strongly on the testing conditions. The severity of road tests, particularly when carried out with customer vehicles is not well defined. Any result obtained in this way is a spot reading which contains no information about its general validity.
A road wear computer program was designed which is able to simulate a very wide range of road wear testing severities and the effect which they have on achievable mileage and wear rating of tread compounds. The program uses the laboratory abrasion test system designed to be used with the Laboratory Abrasion Tester designated as LAT 100. It is shown that good agreement is obtained with actual road test results, not only for the rating of compounds but also for the achieved mileages.