Showing papers on "Natural rubber published in 2009"
TL;DR: In this article, the performance of concrete mixtures incorporating 5%, 7.5% and 10% of discarded tyre rubber as aggregate and cement replacements was investigated, and the results showed that with up to 5% replacement, in each set, no major changes on concrete characteristics would occur, however, with further increase in replacement ratios considerable changes were observed.
591 citations
TL;DR: A critical review of the field focusing on the important parameters affecting rubber-toughening is presented in this paper, which is classified in five categories including roles of matrix ductility, rubber concentration, blend morphology, particle cavitation, and particle/matrix interface.
Abstract: Epoxy resins have been used as structural materials since the late 1940s. Despite their desirable properties such as high strength, excellent creep resistance, and good adhesion, they suffer from low fracture energy. Rubber modification as a major toughening approach to overcome the inherent brittleness of epoxy polymers was introduced during the early 1970s. Since then, a large number of investigations have been conducted to elucidate different aspects of rubber-toughened epoxies. The present work is a critical review of the field focusing on the important parameters affecting rubber-toughening. The studies reviewed are classified in five categories including roles of matrix ductility, rubber concentration, blend morphology, particle cavitation, and particle/matrix interface. It has been tried to provide an in-depth view of the state-of-the-art knowledge in the field and to direct future studies towards exploring new approaches for toughening of epoxy polymers.
352 citations
TL;DR: These composite materials containing 10% Portland cement, 70% and 60% fly ash and 20% and 30% tire rubber particles have sufficient strength for masonry applications.
200 citations
TL;DR: The results of the experiments indicated that the addition of crumb rubber was helpful in increasing the voids in mineral aggregate (VMA) in Superpave mix design and improving rutting resistance of mixture regardless of rubber size as mentioned in this paper.
199 citations
TL;DR: In this article, a melting-blended poly(L-lactide) with four rubber components (ethylene-propylene copolymer, ethylene-acrylic rubber, acrylonitrile-butadiene rubber (NBR), and isoprene rubber (IR) was used to toughen PLA.
Abstract: Poly(L-lactide) (PLA) was melt-blended with four rubber components—ethylene–propylene copolymer, ethylene–acrylic rubber, acrylonitrile–butadiene rubber (NBR), and isoprene rubber (IR)—in an effort to toughen PLA. All the blend samples exhibited distinct phase separation. Amorphous PLA constituted a topologically continuous matrix in which the rubber particles were dispersed. According to Izod impact testing, toughening was achieved only when PLA was blended with NBR, which showed the smallest particle size in its blend samples. In agreement with the morphological analysis, the value of the interfacial tension between the PLA phase and the NBR phase was the lowest, and this suggested that rubber with a high polarity was more suitable for toughening PLA. Under the tensile stress conditions for NBR and IR blend samples, these rubbers displayed no crosslinking and showed a high ability to induce plastic deformation before the break as well as high elongation properties; this suggested that the intrinsic mobility of the rubber was important for the dissipation of the breaking energy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
169 citations
TL;DR: The incorporation of SBR improved the chloride penetration resistance along with the general ionic permeability of the mortar, while increasing its ionic transport resistance and decreasing its electric capacitance as mentioned in this paper.
168 citations
TL;DR: In this article, the authors evaluated the performance of different types of CRM asphalt and found that the crumb rubber content is the primary affecting factor in general, followed by the particle size, and particle size comes last.
167 citations
TL;DR: In this paper, a hybrid nanocomposites containing carbon black (CB) and organo-modified nanoclay (NC) was prepared and X-ray diffraction and transmission electron microscopy (TEM) revealed the presence of intercalated and aggregated structures.
Abstract: Styrene butadiene rubber (SBR) based hybrid nanocomposites containing carbon black (CB) and organo-modified nanoclay (NC) was prepared. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the presence of intercalated, aggregated, and partially exfoliated structures. Incorporating 10 phr NC to the control SBR containing 20 phr CB resulted 153% increase in tensile strength, 157% increase in elongation at break and 144% stress improvement at 100% strain, which showed synergistic effect between the fillers. The dynamic modulus reinforcement of nanocomposites was examined by the Guth, Modified Guth, and Halpin–Tsai equations. For predicting CB filled nanocomposite modulus, the contribution of modified intercalated structure of clay and the ‘nano-unit’ (dual structure) comprising CB–NC should be considered.
157 citations
TL;DR: The microstructure and chemical composition of the leaflets and the rachis of the palm from phoenix dactylifera L were investigated in this article, where the former were used to prepare nanocomposite films using natural rubber as the matrix.
Abstract: The microstructure and chemical composition of the leaflets and the rachis of the palm from phoenix dactylifera L were investigated. It was found that the ratio of slot in the rachis was higher compared to the leaflets. The cellulose content was higher in the rachis whereas the lignin content in the leaflets was twice the one in the rachis. The aspect ratio of the cellulose whiskers extracted from the rachis (around 43) was significantlyhigher compared to the aspect ratio of those from the leaflets which is around 30. The former were used to prepare nanocomposite films using natural rubber as the matrix. These films were obtained bycasting/evaporation. The thermal and mechanical properties of the ensuing nanocomposite films were investigated using differential scanning calorimetry, dynamic mechanical analysis and tensile tests. The stiffness of the natural rubber was significantly increased above the T g. Favorable interactions between the polymeric matrix and the cellulosic nanoparticles were also evidenced.
156 citations
TL;DR: The theory of contact mechanics and rubber friction is extended to the case of surfaces with anisotropic surface roughness and it is shown that the friction coefficient may depend significantly on the sliding direction, while the area of contact depends weakly on the slipping direction.
Abstract: In this paper we extend the theory of contact mechanics and rubber friction developed by one of us (B.N.J. Persson, J. Chem. Phys. 115, 3840 (2001)) to the case of surfaces with anisotropic surface roughness. As an application we calculate the viscoelastic contribution to the rubber friction. We show that the friction coefficient may depend significantly on the sliding direction, while the area of contact depends weakly on the sliding direction. We have carried out experiments for rubber blocks sliding on unidirectionally polished steel surfaces. The experimental data are in a good qualitative agreement with the theory.
155 citations
Journal Article•
TL;DR: In this paper, the authors analyzed the elastic deformations in terms of simple strain energy functions and compared the theoretical results with experimental measurements of the onset of unstable states, and provided new tests of Rivlin's theory and, at least in principle, critical tests of proposed strain energy function for rubber.
Abstract: Materials that undergo large elastic deformations can exhibit novel instabilities. Several examples are considered here: development of an aneurysm on inflating a cylindrical rubber tube; non-uniform stretching on inflating a spherical balloon; expansion of small cavities in rubber blocks when they are subjected to a critical amount of triaxial tension or when they are supersaturated with a dissolved gas; wrinkling of the surface of a block at a critical amount of compression; and the sudden formation of “knots” on twisting stretched cylindrical rods. These various deformations are analyzed in terms of simple strain energy functions using Rivlin's theory of large elastic deformations. The theoretical results are then compared with experimental measurements of the onset of unstable states. Such comparisons provide new tests of Rivlin's theory and, at least in principle, critical tests of proposed strain energy functions for rubber. Moreover, the onset of highly non-uniform deformations has serious implications for the fatigue life and fracture resistance of rubber components.
Patent•
04 Jun 2009
TL;DR: In this article, a diene-based rubber composition for a chafer was proposed to facilitate a rim assembling work, and prevent rubber missing in a bead part at the rim assembly.
Abstract: PROBLEM TO BE SOLVED: To provide a rubber composition for a chafer which facilitates a rim assembling work, and prevents rubber missing in a bead part at the rim assembly, and to provide a pneumatic tire in which the rubber composition is used for the chafer. SOLUTION: In the rubber composition for the tire chafer, not less than 20 pts.mass and nor more than 100 pts.mass of carbon black 20 and nor less than 5.0 pts.mass and not more than 12 pts.mass of polyethylene glycol are blended from 100 pts.mass of diene based rubber component 100. In the rubber composition, nor less than 3 pts.mass and not more than 15 pts.mass of softener is blended from 100 pts.mass of the diene based rubber composition 100. The diene based rubber composition preferably includes: 30-70 mass% of natural rubber; and 30-70 mass% of polybutadiene rubber. COPYRIGHT: (C)2009,JPO&INPIT
TL;DR: In this paper, the results of laboratory research that examines the incorporation of tire rubber granules as a partial replacement for the sand in cement mortars have been presented, showing a decrease in mechanical properties, whereas an increase in chloride ion penetration resistance has been observed.
Abstract: Disposal of worn tires poses a major problem worldwide. In Greece more than 50,000 tons of worn automobile tires are stockpiled annually. This paper presents the results of laboratory research that examines the incorporation of tire rubber granules as a partial replacement for the sand in cement mortars. Physical and mechanical properties of these rubber mixtures are studied while, for the first time, resistance to chloride ion penetration is measured. Results showed a decrease in mechanical properties, whereas an increase in chloride ion penetration resistance has been observed. This implies that cement-based mortar and concrete products, modified with tire rubber granules as a partial replacement for the sand, can be used in applications where mechanical properties are not of prime importance but where high resistance to chloride ion penetration is demanded.
TL;DR: In this article, an epoxidized natural rubber and organically modified nanoclay composites (EC) were prepared by solution mixing, and the obtained nanocomposites were incorporated in nitrile butadiene rubber (NBR) with sulphur as a curing agent.
TL;DR: In this paper, the key technologies for the development of the thin flexible pressure sensor array based on carbon black/silicone rubber nanocomposite are reported, and the piezoresistive mechanism of the nanocomposition is explained by analyzing the changes in effective conductive paths.
Abstract: In this paper, the key technologies for the development of the thin flexible pressure sensor array based on carbon black/silicone rubber nanocomposite are reported. The piezoresistive mechanism of the nanocomposite is explained by analyzing the changes in effective conductive paths. The technical data of the sensor system are given. With the measurement range of 0-1 MPa, the maximum measurement deviation is less than 30 kPa.
TL;DR: In this article, a series of ionic liquids have been tested in regard to an improved interaction between rubber and carbon nanotubes to ensure better rubber/multi-walled carbon-nanotube compatibility and to enhance the dispersibility.
TL;DR: In this article, the pyrolysis of waste tires in continuous mode has been studied in a pilot plant provided with a conical spouted bed reactor, in the 425−600 °C range, by feeding two types of tire materials with different contents of natural and synthetic rubber.
Abstract: The pyrolysis of waste tires in continuous mode has been studied in a pilot plant provided with a conical spouted bed reactor, in the 425−600 °C range, by feeding two types of tire materials with different contents of natural and synthetic rubber. The properties of the pyrolysis products have been characterized using different techniques for both the volatile and solid fraction. The liquid has been analyzed by means of GC/MS, GC×GC and simulated distillation, and the residual carbon black by elemental analysis and surface characterization. Neither temperature nor tire composition has a significant effect on the yields of gas, liquid and residual carbon black fractions, but they considerably affect product properties. The contents of natural rubber and styrene−butadiene rubber in the tire have a significant effect on the liquid composition (contents of aromatics and interesting raw materials, such as styrene and limonene). The carbon black obtained at 600 °C has a high surface area and is suitable for acti...
TL;DR: In this paper, the effect of carbon black loading on the swelling and compression set behavior of styrene butadiene (SBR) and NBR compounds was investigated and the obtained results of five different compositions for SBR and nBR with 0, 20, 30, 50 and 70 phr of CB were compared.
TL;DR: In this article, the authors measured the hydrogen content of EPDM and NBR composites with carbon black, silica, and no fillers were exposed to hydrogen gas at a maximum pressure of 10MPa; then, blister tests and measurement of hydrogen content were conducted.
Book•
14 Sep 2009TL;DR: In this article, the elastomer matrix is used for reinforcement of fillers in polymers of larger connectivity, such as branched polymers and polymeric fractals.
Abstract: 1. Introduction 2. Basics about polymers 3. Many chain systems: melts and screenings 4. Rubber formation 5. The elastomer matrix 6. Polymers of larger connectivity: branched polymers and polymeric fractals 7. Reinforcing fillers 8. Hydrodynamic reinforcement of elastomers 9. Polymer-filler interactions 10. Filler-filler interactions.
TL;DR: In this paper, an indirect heated fluidized bed process has been used for the pyrolysis of synthetic and natural rubber, and the throughput capacity for the continuously running plant was 500-3000 g/h.
TL;DR: In this article, the authors compared the hardness of natural rubber (NR) vulcanizates containing various fillers, and their mechanical properties were compared and related to the degree of filler dispersion.
TL;DR: A new way to dispose off waste tyres by reusing the waste tyre rubber (WTR) for oil absorptive material production is provided by graft copolymerization-blending method, and oil-absorption processes in pure toluene and crude oil diluted with toLUene were found to adhere to first-order absorption kinetics.
TL;DR: In this article, a self-designed pan-mill type mechanochemical reactor was used for the devulcanization of ground tire rubber (GTR) and the results showed that the tensile properties of the dGTR/NR vulcanizates were much better than those of the raw ground-tire rubber.
Abstract: The devulcanization of ground tire rubber (GTR) was carried out with a self-designed pan-mill type mechanochemical reactor. Gel fraction and crosslink density measurements confirmed the occurrence of stress induced mechanochemical devulcanization of GTR. The partially devulcanized GTR (dGTR) was blended with virgin natural rubber (NR) at different ratios. The curing characteristics and mechanical properties of these composites were investigated and compared with those composites of raw ground tire rubber (rGTR) and NR. The results showed that the tensile properties of the dGTR/NR vulcanizates were much better than those of the rGTR/NR vulcanizates, which are comparable to or even better than the virgin vulcanizate, indicating the significant benefit of mechanochemical devulcanization. At the GTR content of 10%, the tensile strength of the dGTR/NR blends increased to 23.2 MPa from 13.7 MPa of the rGTR/NR blends, enhanced by 69% through partial devulcanization of GTR, and the elongation at break increased by 47%.
TL;DR: In this paper, the effect of the proportion of preblending matrix asphalt and properties of crumb rubber on performance of CRMA have been investigated, and the experimental results indicated that the CRMA has better performance compared with matrix asphalt.
TL;DR: In this article, the preparation, characterization, and physical properties of nanoparticies-filled composites consisting of multiwall carbon nanotubes (MWCNT) and styrene-butadiene rubber and nitrile-butane rubber were described.
Abstract: The present article describes preparation, characterization, and physical properties of nanoparticies-filled composites consisting of multiwall carbon nanotubes (MWCNT) and styrene-butadiene rubber and nitrile-butadiene rubber. The reinforcing MWCNT fillers were synthesized by chemical vapor deposition on iron and cobalt catalysts supported by calcium carbonate substrates. These MWCNT were further treated with nitric acid to produce hydroxyl and carbonyl functional groups on the carbon nanotubes (CNT) surfaces. Of particular importance is that these functionalized CNTs were found to exert profound influence on the elastomeric matrices, particularly the vulcanization activation energy, resistance to solvent swelling, enhanced glass transition temperature, and improved storage and loss moduli.
TL;DR: In this article, the authors investigated the mechanical behavior of natural rubber/organo-modified montmorillonite vulcanisates produced by melt mixing with various filler contents and provided an evaluation of the filler percolation threshold.
12 May 2009
TL;DR: This study designs the actuator without fiber using nonlinear FEM (Finite Element Method) and derived efficient shape and makes a soft hand consisting of three curling actuators, which could be manufactured by simple casting process.
Abstract: In medical and biotechnology fields, soft devices are required because of their high safety from low mechanical impedance. FMA (Flexible Microactuator) is one of the typical soft actuators. It consists of fiber-reinforced rubber structure with multi air chambers and realizes bending motion pneumatically. It has been applied to robot hands, robot legs and so on. High potential of FMA has been confirmed by many experiments reported in several papers. However in fabrication process of the actuator, it is difficult to embed the reinforced fiber in the rubber structure. In this study, we aim at development of a fiber less FMA realizing quite large motion, which can be said curling motion, and a soft hand using the actuators. We design the actuator without fiber using nonlinear FEM (Finite Element Method) and derived efficient shape. The actuator is fabricated through micro rubber casting process including micro machining process for molds, micro vacuum rubber molding process and rubber bonding process with surface improvement by excimer light. Basic driving experiments of the actuator showed that it realized curling motion which agreed well with FEM results. And the actuator could grasp a fish egg without breaking. Additionally, we made a soft hand consisting of three curling actuators. This hand also could be manufactured by simple casting process. The developed hand works opening and closing motions well.
TL;DR: The nonlinear viscoelastic behavior of the composites of natural rubber filled with surface-modified nanosilica was studied with reference to silica loading in this article.
Abstract: The nonlinear viscoelastic behavior of the composites of natural rubber filled with surface-modified nanosilica was studied with reference to silica loading. The effect of temperature on the nonlinear viscoelastic behavior has been investigated. It was observed that Payne effect becomes more pronounced at higher silica loading. The filler characteristics such as particle size, specific surface area, and the surface structural features were found to be the key parameters influencing the Payne effect. A nonlinear decrease in storage modulus with increasing strain was observed for unfilled compounds also. The results reveal that the mechanism includes the breakdown of different networks namely the filler−filler network, the weak polymer−filler network, the chemical network, and the entanglement network. The model of variable network density proposed by Maier and Goritz has been applied to explain the nonlinear behavior. The activation energy of desorption was calculated and found to be within the range of Va...
TL;DR: In this paper, a carbon black-filled rubber compound is loaded with harmonic deformations under different frequencies and amplitudes and the stationary stress response is evaluated in terms of the storage and the loss modulus or, equivalently, the dynamic modulus and loss angle.
Abstract: Filler-reinforced elastomers are extremely complicated materials with pronounced deformation and temperature history-dependent material properties. In the current paper, the dynamic material behaviour is investigated and modelled. To this end, a carbon black-filled rubber compound is loaded with harmonic deformations under different frequencies and amplitudes and the stationary stress response is evaluated in terms of the storage and the loss modulus or, equivalently, in terms of the dynamic modulus and the loss angle. In this essay, detailed experimental investigations of the dynamic material properties of carbon black-filled elastomers are provided and a new three-dimensional constitutive approach of finite nonlinear viscoelasticity to represent the observed material behaviour is developed.