bluuebunny/crossref_metadata_2025_split huggingface dataset:
Composition of Color Substances of Hevea Brasiliensis Natural Rubber
Authors: Sakdapipanich Jitladda , Insom Kittipong , Phupewkeaw Nataphon 
Published: February 2011

Abstract
It is accepted that NR gives naturally occurring color, which restrict many applications such as light-color products. Therefore, characterization of color substances presenting in NR is very useful to develop the certain methodology to eliminate them completely or partly from NR in the future. In this work, an attempt was made to purify and characterize the color substances extracted from various fractions of Hevea rubber latex by certain methods, using high-resolution structural characterization techniques. It was found that the content of color substances extracted from fresh latex (FL), rubber cream, bottom fraction (BF), Frey Wyssling (FW) particles and STR 20 were different. Based on the high-resolution spectroscopic analyzes, it was found that the color substances extracted from NR were composed of carotenoids, tocotrienol esters, fatty alcohol esters, tocotrienols, unsaturated fatty acids, fatty alcohols, diglyceride and monoglyceride. The results will be useful for rubber-technologist to identify the origin to make obnoxious color in natural rubber, especially in some applications which are restricted by such the color.
Fiber Structure and Mechanical Properties of Electrospun Butyl Rubber with Different Types of Carbon Black
Authors: Threepopnatkul P. , Murphy D. , Mead J. , Zukas W. 
Published: February 2011

Abstract
Breathable butyl rubber non-woven mats have been successfully produced by the electrospinning technique, providing a fibrous membrane with controlled porosity and surface area. These properties are directly related to the barrier properties of the product, including water vapor transmission, air flow resistance, aerosol resistance, and the transportation of chemical vapors. Butyl rubber is also known as a highly chemical resistant elastomer material, which can be used for applications requiring high elongation. The use of carbon black filled elastomers provides the ability to tailor the properties, such as processability, mechanical properties, and barrier properties through proper selection of carbon black type and loading. In this work, the structure and mechanical properties of electrospun butyl rubber non-woven mats were investigated using a series of carbon black types with variation in particle size and structure. Fiber diameter decreased with decreasing particle size and increasing carbon black structure. Mechanical properties can be explained by variation in density and fiber morphology of membranes. Decreasing carbon black particle size and increasing structure decreased the density, and increased tensile strength, ultimate elongation and modulus.
Thermoplastic Vulcanizates by Reaction-Induced Phase Separation of a Miscible Poly(ε-Caprolactone)/Epoxy System
Authors: l'Abee R. M. A. , Goossens J. G. P. , van Duin M. 
Published: February 2011

Abstract
A new method for the preparation of thermoplastic vulcanizates (TPVs) was successfully applied. Starting with a miscible system of a semi-crystalline thermoplastic polymer and an elastomer precursor, phase separation was induced by the increase in molecular weight during selective crosslinking of the elastomer precursor. As a model system, the semi-crystalline thermoplastic poly(Ε-caprolactone) (PCL) was used in combination with a rubbery epoxy resin based on poly(propylene oxide) (PPOn-epoxy). This approach enables the dispersion of up to 80 wt% of crosslinked rubber in a thermoplastic matrix, providing morphologies that are typical for TPVs. A range in rubber particle size of 0.5 to 3 μm was obtained by this new method, without the need of blend compatibilization or dynamic processing. The materials exhibit mechanical and rheological properties typical for TPVs and the rubber particles feature a high crosslink density. At high curing temperatures and high PPOn-epoxy contents, connectivity of the rubber particles is observed, which is attributed to the phase separation mechanism. Connectivity of the rubber particles has a negative influence on both the mechanical properties and the rheological behavior.
Preparation of Cyclized Deproteinized Natural Rubber in Latex State via a Combination of Benzotrichloride and Sulfuric Acid System, and Its Properties
Authors: Riyajan Sa-ad , Tanaka Yasuyuki , Sakdapipanich Jitladda T. 
Published: February 2011

Abstract
Partially cyclized deproteinized natural rubber (DPNR) in latex form was successfully prepared by using a combination of sulfuric acid (H2SO4) and benzotrichloride (PhCCl3) in the presence of Terric 320 as a non-ionic surfactant. The main parameters of the cyclization process such as various reaction times, dry rubber contents, concentrations of catalyst and temperatures were investigated. The resulting rubber was subjected to characterization by proton Nuclear Magnetic Resonance (1H-NMR), Fourier-Transform Infrared spectrometer (FTIR), Thermal Gravimetric Analysis (TGA), and Differential Scan Calorimeter (DSC). In addition, the topology of partially cyclized rubber was also analyzed by Transmittance Electron Microscopy (TEM). The mechanism will be also discussed. It was interesting to note that the obtained partially cyclized rubber using this catalyst system contained no gel, which was easily soluble in rubber solvents. This is different from the partially cyclized rubber obtained from the other methods. Through, using structural characterization, it was found that the PhCCl3 linked onto the rubber chain. It was also found that the thermal stability of this cyclized rubber was better than that of normal rubber. The efficiency of cyclization in this system could be increased by an increase of PhCCl3 concentration.
Study of the Influence of Microwaves in the Mechanism of Sulfenamide Accelerated Vulcanization of Natural Rubber Using Squalene as a Model Compound
Authors: Vega B. , Agulló N. , Borrós S. 
Published: February 2011

Abstract
The natural rubber vulcanization mechanism has been studied using microwaves as a heating source. The influence of such heating system on the mechanism reaction has been elucidated. In order to simplify the study of this process, squalene has been used as a Model Compound Vulcanization (MCV) for natural rubber and N-cyclohexyl-2-benzothiazolesulfenamide (CBS) as an accelerator. The accelerator fading, the crosslinking degree, the reversion process and the effect of the double bond have been studied and the results have been compared with previous results of our group using MCV with conventional heating. As well as the expected reaction rate increase, a noticeable change in the crosslink degree has been observed. Furthermore, some differences have been detected in the amount of the intermediate compounds formed during the reaction and in the sulfur transfer to the squalene chain. Strong differences have been also observed regarding the role of the activator in the vulcanization when microwaves are used.
Generalized Concept of the Reinforcement of Elastomers. Part 3: Self-Reinforcement by the Formation of Continuous Hard Phase in Segmented Polyurethane Elastomer
Authors: Fukahori Yoshihide 
Published: February 2011

Abstract
The author proposed the third concept in the reinforcement of elastomers for segmented polyurethane with the direct observation by microscopic techniques. The structure in segmented polyurethane elastomers fundamentally consists of three domains of different sizes, two kinds of micro-domain, cluster of 100 nm in diameter and spherulite of µm order. Of the micro-domains, one is the hard-segment (HS)-rich micro-domain consisting of hard segment (4 nm thickness) and soft segment (7 nm) and the other is the hard-segment (HS)-poor micro-domain of hard segment (4 nm) and soft segment (15∼20 nm). The HS cluster is constructed by the assembly of the HS-rich micro-domains. The spherulite seems to be composed of the dense packing of the HS cluster, growing up radially or circularly from the center to the outside surface. From physical and mechanical points of view, we can regard the above structures in the segmented polyurethane as bi-continuous structure of the HS clusters whose volume fraction is 0.2, and the matrix phase consisting of the HS-poor domains (0.8 in the volume fraction). The characteristic stress-strain relation of the segmented polyurethane is generated by the combination of both the continuous structures. That is, the initial very high stress (modulus) at small extension and the following gradual increase in stress at medium extension mainly result from the extension and the sliding of the HS cluster, respectively. The very large stress-upturn at large extension and the final great tensile strength are generated by the contribution of both the continuous structures. Thus, the third reinforcement is achieved by the formation of bicontinuous structure of the hard and strong cluster and also the strong matrix phase, in which the absolute structural defects seem not to be included.
Polyhedral Oligomeric Silsesquioxane (POSS) Nanoparticles as New Crosslinking Agent for Functionalized Rubber
Authors: Sahoo Suchismita , Bhowmick Anil K. 
Published: February 2011

Abstract
Polyhedral oligomeric silsesquioxane (POSS) was synthesized with hydroxyl functional groups and the nanoparticles were characterized by infrared spectroscopy and transmission electron microscopy. They were found to have an average diameter of 50 nm.The effect of these synthesized POSS nanoparticles as curing agent on fluorocarbon rubber (FKM) and carboxylated nitrile rubber (XNBR) was studied with special reference to mechanical, dynamic mechanical properties and swelling behavior. The hydroxyl groups of the POSS nanoparticles were observed to effectively crosslink FKM and XNBR, which was indicated by a tremendous improvement in mechanical properties. A remarkable positive shift in glass transition temperature (Tg) was observed, which further supported the crosslinking effect of POSS nanoparticles. Formation of crosslink was confirmed from the increase in the volume fraction of rubber in swollen gel. In the case of FKM, when MgO as activator and CaO as promoter were used along with POSS nanoparticles, maximum improvement in mechanical properties was observed.
The Effect of a Dwell Period on Fatigue Crack Growth Rates in Filled SBR and NR
Authors: Harbour Ryan J. , Fatemi Ali , Mars Will V. 
Published: February 2011

Abstract
Loading conditions for rubber components are often more complex than the constant amplitude signals used in material characterization. During a series of uniaxial fatigue crack growth experiments on filled SBR under variable amplitude loading conditions, test signals that included a dwell period produced higher crack growth rates than corresponding constant amplitude test signals without a dwell period. These test signals alternated periods of cyclic loading with dwell periods ranging from 1 to 100 seconds at a near zero stress level. Dwell period tests produced average experimental crack growth rates up to 30 times greater than constant amplitude crack growth rates in filled SBR. The length of dwell time and the number of applied cycles between dwell periods were the most significant influences on the crack growth results. An empirical model was developed that captured the dwell effect based on these parameters. Dwell periods also produced increased crack growth rates in natural rubber, but the effect was less significant. It is proposed that the effect is caused by the time-dependent recovery in the rubber microstructure at the crack tip producing a localized and temporary elevated stress-state during loading events immediately following a dwell period. Current fatigue prediction methods do not account for the dwell effect.
Trapped Entanglements in Polymer Networks
Authors: Lang Michael , Kreitmeier Stefan , Göritz Dietmar 
Published: February 2011

Abstract
This work focuses on density, complexity, and experimentally observable effects of trapped entanglements in polymer networks. Using the bond-fluctuation method we crosslinked and end-linked systems with a random initial distribution of polymer and crosslinker. The structure of the generated networks has been analyzed by knot theory and graph theory concerning defects, ring structures, and trapped entanglements, resulting in a detailed description of network topology and connectivity. The knowledge on network structure is used to analyze computer simulations of swelling and solfraction experiments. The simulated swelling experiments show that the size of the fully swollen network depends strongly on the presence of trapped entanglements although the zero second Money-Rivlin term upon deformation indicates the absence of a tube like environment for individual network chains. Permanently trapped rings and the formation of network defects affect the weight of the measured gel component as function of the degree of crosslinking. The experimentally observed shift in size of the gel can be estimated based on the data of this study and is typically smaller than the shift due to ineffective reactions that lead to the formation of dangling rings and network defects.
New Developments in Dynamically Cured PP—EPDM Blends
Authors: López-Manchado Miguel A. , Arroyo Miguel , Kenny José M. 
Published: February 2011

Abstract
Different procedures for preparing thermoplastic vulcanizates (TPVs), based on isotactic polypropylene (iPP) and ethylene—propylene—diene terpolymer rubber (EPDM), are used and analyzed in this work. In order to determine the effect of the vulcanization method on material properties, a rheological study, dynamic-mechanical analysis, mechanical properties and morphological study have been carried out. In all cases, the sulfur is used as crosslinking agent of the elastomeric phase. It has been shown that the dynamically cured blends (referred in the work as V2 and V3) present better properties in relation to those statically cured (V1) and uncrosslinked (V). Thus, the elastic ability, mechanical properties and rheological characteristics of these systems sensibly increase when the samples are dynamically vulcanized. Morphological analysis performed by scanning electron microscopy (SEM) is clearly in agreement with the analyzed properties, showing a better dispersion between both polymeric chains, when the blends are dynamically cured. These results seem to indicate that the dynamic vulcanization process gives rise to the formation of a thermally stable three-dimensional network, and as a consequence of it, a sensible increase of the properties is obtained.
Rubber Nanocomposites: Morphology and Mechanical Properties of BR and SBR Vulcanizates Reinforced by Organophilic Layered Silicates
Authors: Ganter Markus , Gronski Wolfram , Reichert Peter , Mülhaupt Rolf 
Published: February 2011

Abstract
Rubber compounds based on butadiene rubber (BR) or styrene—butadiene rubber (SBR) containing organophilic layered silicates were prepared. Organophilic silicates were swollen in a rubber/toluene solution. Matrix—filler reactive bonding was performed by adding bis(triethoxysilylpropyl)-tetrasulfan (TESPT) during swelling. Excellent dispersion of organoclay nanofillers in rubber matrices was demonstrated by transmission electron microscopy (TEM) and atomic force microscopy (AFM) exhibiting intercalated and partially exfoliated silicate layers. Matrix—filler interfacial coupling by TESPT led to reduced strain at break and reduced hysteresis for both organoclay and silica-based vulcanizates as expected for successful matrix filler coupling. Organoclay vulcanizates exhibited enhanced hysteresis when compared to silica compounds. This is related to orientation and sliding of anisotropic silicate layers, as determined by online wide-angle X-ray scattering (WAXS) measurements during cyclic tensile testing.
High-Resolution Solid State NMR Investigation of the Filler-Rubber Interaction: Part III. Investigation on the Structure and Formation Mechanism of Carbon Gel in the Carbon Black-Filled Styrene—Butadiene Rubber
Authors: Dutta N. K. , Roy Choudhury N. , Haidar B. , Vidal A. , Donnet J. B. , Delmotte L. , Chezeau J. M. 
Published: February 2011

Abstract
This investigation describes the elastomer—filler interaction and its formation mechanism using solid state high-resolution, high-speed 1H magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. Pulsed NMR measurements were carried out on pure styrene-butadiene rubber (SBR), and solvent extracted carbon gels from freshly prepared and storage matured master batches. The effects of filler loading, storage maturation, severity of extraction and experimental temperature on the elastomer-filler interaction were examined and discussed. High resolution in NMR was achieved by higher temperature/low spinning rate, room temperature/high spinning and combined rotation and multiple-pulse spectroscopy (CRAMPS) techniques. High-speed magic-angle spinning (MAS) was found to be the most suitable method to achieve high resolution. Proton spin—spin relaxation time, T2, was measured successfully for each of the principal resonance species present in the samples. These measurements reveal an insight into the site-specific nature of the polymer—filler interaction. The relative immobilization of the dynamics of different protons, due to the presence of carbon black filler, and their temperature dependence evidence that the main chain vinyl proton is the most significantly immobilized one compared to the aromatic and methylene species. The effects of storage maturation and severity of extraction on the dynamics of the conformational jump have also been discussed. This work clearly demonstrates the importance of unsaturation on the bound rubber formation. It also provides first direct physical evidence confirming the hypothesis that bound rubber variation during the storage maturation is due to slow progressive replacement of short rubber chains by larger ones.
High-Resolution Latex State 13C-NMR Spectroscopy: Part II. Effect of Particle Size and Temperature
Authors: Kawahara Seiichi , Isono Yoshinobu , Washino Keiko , Morita Toshiko , Tanaka Yasuyuki 
Published: February 2011

Abstract
Latex state C-NMR measurements were made for colloidal dispersions of polymer, using the observation conditions similar to those used in solution state measurement. The colloidal dispersion which showed broad and bimodal distributions in particle size was fractionated by centrifugation into four fractions with different volume mean particle diameter ranging from 0.121 to 1.31 µm with narrow and unimodal distributions. The signal to noise ratio, half width and intensity of each resolved carbon resonance for the fractionated dispersions were dependent upon the particle diameter. The intensity of the carbon resonances increased to 100% as the particle diameter decreased and temperature was raised. This is explained with respect to the increase in diffusion coefficient of Brownian motion of the particle. The intensity and the half width of the signals were superimposed against the diffusion coefficient of Brownian motion.
Ultrasonic Devulcanization of Precipitated Silica-Filled Silicone Rubber
Authors: Shim Sang E. , Isayev A. I. 
Published: February 2011

Abstract
This investigation involves the recycling of precipitated silica-filled silicone rubber using a continuous ultrasonic reactor. The processing conditions utilized in devulcanization of the filled systems were similar to those in our previous work on unfilled systems. Significant differences were observed in devulcanization of unfilled and filled systems. A decrease in gel fraction and crosslink density was sufficient for devulcanized silica-filled silicone rubber to be reprocessed and revulcanized. The cure behavior of silicone rubber and the mechanical properties of virgin, and revulcanized rubber were measured. Results showed that unfilled silicone rubbers gave no change in vulcanizate mechanical properties after revulcanization. However, in the filled rubbers there was a decrease in the mechanical properties of revulcanizates. In order to achieve an improvement in the properties, devulcanized filled rubbers were blended with virgin filled rubber in various proportions. The obtained results indicated a considerable enhancement of the performance characteristics of these blend vulcanizates.
Ultrasonic Devulcanization Reactors for Recycling of GRT: Comparative Study
Authors: Yun Jushik , Oh Jeonq Seok , Isayev A. I. 
Published: February 2011

Abstract
The present paper describes the comparative study of a continuous ultrasonic devulcanization of ground tire rubber (GRT) using two reactors. The devulcanization zone in the first reactor (coaxial reactor) is located at the exit from an extruder without imposition of additional shearing. In the second reactor (barrel reactor), the devulcanization zone is located in barrel where additional shearing takes place due to screw rotation. Gel fraction, crosslink density, cure behavior and physical properties of GRT obtained in these two reactors were measured. Also, the distribution of gel fraction and crosslink density at various locations in the devulcanization zone of the barrel reactor were determined. Gel fraction and crosslink density show that GRT in both reactors is partially devulcanized. A unique correlation between gel fraction and crosslink density obtained in both reactors indicated that additional shearing had a positive influence on improving the efficiency of devulcanization. Under the optimal devulcanization condition, the physical properties of revulcanized GRT and the output are higher in the barrel reactor. Power consumption density in the barrel reactor is found to be significantly higher.
Characterization and Constitutive Modeling of a Plasticized Poly(vinyl Chloride) for a Broad Range of Strain Rates
Authors: Wang Yan , Arruda Ellen M. , Przybylo Phillip A. 
Published: February 2011

Abstract
The mechanical behavior, morphological characterization and constitutive modeling of plasticized poly(vinyl chloride) (or PVC) are studied in this paper. The plasticized PVC is tested to large strains over a broad range of strain rates. Uniaxial and plane strain compression data at various constant strain rates ranging from −0.001 to −10 s−1 are collected on a conventional servohydraulic test system. Additional uniaxial impact compression data at approximately constant strain rates ranging from −1160 to −5560 s−1 are obtained using an aluminum split Hopkinson pressure bar apparatus. The large strain load/unload response of the plasticized PVC is nonlinear, it contains hysteresis and plastic deformation, and the initial response is highly rate dependent when the strain rate spans the transition zone between quasi-static and impact strain rates at room temperature. The morphology of plasticized PVC is analyzed via differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), and described as a physically entangled network. A three-dimensional rate dependent constitutive model for plasticized PVC is developed and shown to successfully predict its stress—strain behavior over a broad range of strain rates.