Science.gov

Sample records for non-affine rubber elasticity

  1. Particle displacements in the elastic deformation of amorphous materials: Local fluctuations vs. non-affine field

    NASA Astrophysics Data System (ADS)

    Goldenberg, C.; Tanguy, A.; Barrat, J.-L.

    2007-10-01

    We study the local disorder in the deformation of amorphous materials by decomposing the particle displacements into a continuous, inhomogeneous field and the corresponding fluctuations. We compare these fields to the commonly used non-affine displacements in an elastically deformed 2D Lennard-Jones glass. Unlike the non-affine field, the fluctuations are very localized, and exhibit a much smaller (and system size independent) correlation length, on the order of a particle diameter, supporting the applicability of the notion of local "defects" to such materials. We propose a scalar "noise" field to characterize the fluctuations, as an additional field for extended continuum models, e.g., to describe the localized irreversible events observed during plastic deformation.

  2. Elastic instabilities in rubber

    NASA Astrophysics Data System (ADS)

    Gent, Alan

    2009-03-01

    Materials that undergo large elastic deformations can exhibit novel instabilities. Several examples are described: development of an aneurysm on inflating a rubber tube; non-uniform stretching on inflating a spherical balloon; formation of internal cracks in rubber blocks at a critical level of triaxial tension or when supersaturated with a dissolved gas; surface wrinkling of a block at a critical amount of compression; debonding or fracture of constrained films on swelling, and formation of ``knots'' on twisting stretched cylindrical rods. These various deformations are analyzed in terms of a simple strain energy function, using Rivlin's theory of large elastic deformations, and the results are 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. [4pt] References: [0pt] R. S. Rivlin, Philos. Trans. Roy. Soc. Lond. Ser. A241 (1948) 379--397. [0pt] A. Mallock, Proc. Roy. Soc. Lond. 49 (1890--1891) 458--463. [0pt] M. A. Biot, ``Mechanics of Incremental Deformations'', Wiley, New York, 1965. [0pt] A. N. Gent and P. B. Lindley, Proc. Roy. Soc. Lond. A 249 (1958) 195--205. [0pt] A. N. Gent, W. J. Hung and M. F. Tse, Rubb. Chem. Technol. 74 (2001) 89--99. [0pt] A. N. Gent, Internatl. J. Non-Linear Mech. 40 (2005) 165--175.

  3. Rubber elasticity: From topology to filled elastomers

    SciTech Connect

    Heinrich, G.; Vilgis, T.A.

    1993-12-31

    Various new aspects in the elasticity of rubbers and statistics of unfilled and filled elastomers, together with various consequences for practical application are discussed. It is shown that the role of network topology is crucial in the statistics of rubbers. This is seen mostly on the influence of heterogeneities of crosslink density which determine the elastic modulus, ultimate properties as well as the dynamical behavior. The filler effects, entanglements in filled rubbers, and the filler/bound rubber/mobile rubber problem are discussed from a novel point of view. A localization model is adopted, where it can be shown that on a rough (filler) surface more polymer can be adsorbed compared to a flat surface with similar energetic properties. The role of carbon black networking and fractal properties of the filler are discussed in relation to the dynamic-mechanical properties of the elastomer.

  4. The role of pressure in rubber elasticity.

    PubMed

    Bower, A F; Weiner, J H

    2004-06-22

    We describe a series of molecular dynamics computations that reveal an intimate connection at the atomic scale between difference stress (which resists stretches) and pressure (which resists volume changes) in an idealized elastomer, in contrast to the classical theory of rubber elasticity. Our simulations idealize the elastomer as a "pearl necklace," in which the covalent bonds are stiff linear springs, while nonbonded atoms interact through a Lennard-Jones potential with energy epsilon(LJ) and radius sigma(LJ). We calculate the difference stress t(11)-(t(22)+t(33))/2 and mean stress (t(11)+t(22)+t(33))/3 induced by a constant volume extension in the x(1) direction, as a function of temperature T and reduced density rho(*)=Nsigma(IJ) (3)/nu. Here, N is the number of atoms in the simulation cell and nu is the cell volume. Results show that for rho(*)<1, the difference stress is purely entropic and is in good agreement with the classical affine network model of rubber elasticity, which neglects nonbonded interactions. However, data presented by van Krevelen [Properties of Polymers, 3rd ed. (Elsevier, Amsterdam, 1990), p. 79] indicate that rubber at standard conditions corresponds to rho(*)=1.2. For rho(*)>1, the system is entropic for kT/epsilon(LJ)>2, but at lower temperatures the difference stress contains an additional energy component, which increases as rho(*) increases and temperature decreases. Finally, the model exhibits a glass transition for rho(*)=1.2 and kT/epsilon(LJ) approximately 2. The atomic-scale processes responsible for generating stress are explored in detail. Simulations demonstrate that the repulsive portion of the Lennard-Jones potential provides a contribution sigma(nbr)>0 to the difference stress, the attractive portion provides sigma(nba) approximately 0, while the covalent bonds provide sigma(b)<0. In contrast, their respective contributions to the mean stress satisfy Pi(nbr)<0, Pi(nba)>0, and Pi(b)<0. Analytical calculations, together

  5. The role of pressure in rubber elasticity

    NASA Astrophysics Data System (ADS)

    Bower, A. F.; Weiner, J. H.

    2004-06-01

    We describe a series of molecular dynamics computations that reveal an intimate connection at the atomic scale between difference stress (which resists stretches) and pressure (which resists volume changes) in an idealized elastomer, in contrast to the classical theory of rubber elasticity. Our simulations idealize the elastomer as a "pearl necklace," in which the covalent bonds are stiff linear springs, while nonbonded atoms interact through a Lennard-Jones potential with energy εLJ and radius σLJ. We calculate the difference stress t11-(t22+t33)/2 and mean stress (t11+t22+t33)/3 induced by a constant volume extension in the x1 direction, as a function of temperature T and reduced density ρ*=NσIJ3/ν. Here, N is the number of atoms in the simulation cell and ν is the cell volume. Results show that for ρ*<1, the difference stress is purely entropic and is in good agreement with the classical affine network model of rubber elasticity, which neglects nonbonded interactions. However, data presented by van Krevelen [Properties of Polymers, 3rd ed. (Elsevier, Amsterdam, 1990), p. 79] indicate that rubber at standard conditions corresponds to ρ*=1.2. For ρ*>1, the system is entropic for kT/εLJ>2, but at lower temperatures the difference stress contains an additional energy component, which increases as ρ* increases and temperature decreases. Finally, the model exhibits a glass transition for ρ*=1.2 and kT/εLJ≈2. The atomic-scale processes responsible for generating stress are explored in detail. Simulations demonstrate that the repulsive portion of the Lennard-Jones potential provides a contribution σnbr>0 to the difference stress, the attractive portion provides σnba≈0, while the covalent bonds provide σb<0. In contrast, their respective contributions to the mean stress satisfy Πnbr<0, Πnba>0, and Πb<0. Analytical calculations, together with simulations, demonstrate that mean and difference stresses are related by σnbr=-AΠnbr,

  6. A new paradigm for the molecular basis of rubber elasticity

    SciTech Connect

    Hanson, David E.; Barber, John L.

    2015-02-19

    The molecular basis for rubber elasticity is arguably the oldest and one of the most important questions in the field of polymer physics. The theoretical investigation of rubber elasticity began in earnest almost a century ago with the development of analytic thermodynamic models, based on simple, highly-symmetric configurations of so-called Gaussian chains, i.e. polymer chains that obey Markov statistics. Numerous theories have been proposed over the past 90 years based on the ansatz that the elastic force for individual network chains arises from the entropy change associated with the distribution of end-to-end distances of a free polymer chain. There are serious philosophical objections to this assumption and others, such as the assumption that all network nodes undergo affine motion and that all of the network chains have the same length. Recently, a new paradigm for elasticity in rubber networks has been proposed that is based on mechanisms that originate at the molecular level. Using conventional statistical mechanics analyses, quantum chemistry, and molecular dynamics simulations, the fundamental entropic and enthalpic chain extension forces for polyisoprene (natural rubber) have been determined, along with estimates for the basic force constants. Concurrently, the complex morphology of natural rubber networks (the joint probability density distributions that relate the chain end-to-end distance to its contour length) has also been captured in a numerical model. When molecular chain forces are merged with the network structure in this model, it is possible to study the mechanical response to tensile and compressive strains of a representative volume element of a polymer network. As strain is imposed on a network, pathways of connected taut chains, that completely span the network along strain axis, emerge. Although these chains represent only a few percent of the total, they account for nearly all of the elastic stress at high strain. Here we provide a brief

  7. Disorder, pre-stress and non-affinity in polymer 8-chain models

    NASA Astrophysics Data System (ADS)

    Cioroianu, Adrian R.; Spiesz, Ewa M.; Storm, Cornelis

    2016-04-01

    To assess the role of single-chain elasticity, non-affine strain fields and pre-stressed reference states we present and discuss the results of numerical and analytical analyses of a modified 8-chain Arruda-Boyce model for cross-linked polymer networks. This class of models has proved highly successful in modeling the finite-strain response of flexible rubbers. We extend it to include the effects of spatial disorder and the associated non-affinity, and use it to assess the validity of replacing the constituent chain's nonlinear elastic response with equivalent linear, Hookean springs. Surprisingly, we find that even in the regime of linear response, the full polymer model gives very different results from its linearized counterpart, even though none of the chains are stretched beyond their linear regime. We demonstrate that this effect is due to the fact that the polymer models are under considerable pre-stress in their ground state. We show that pre-stress strongly suppresses non-affinity in these unit cell models, resulting in a marked stiffening of the bulk response. Polymer networks with some degree of flexibility are thus intrinsically prestressed, and one effect of such prestresses is to reduce non-affine deformations. Combined, these findings may help explain why fully affine mechanical models, in many cases, predict the bulk mechanical response of disordered polymer networks so well.

  8. A new paradigm for the molecular basis of rubber elasticity

    DOE PAGESBeta

    Hanson, David E.; Barber, John L.

    2015-02-19

    The molecular basis for rubber elasticity is arguably the oldest and one of the most important questions in the field of polymer physics. The theoretical investigation of rubber elasticity began in earnest almost a century ago with the development of analytic thermodynamic models, based on simple, highly-symmetric configurations of so-called Gaussian chains, i.e. polymer chains that obey Markov statistics. Numerous theories have been proposed over the past 90 years based on the ansatz that the elastic force for individual network chains arises from the entropy change associated with the distribution of end-to-end distances of a free polymer chain. There aremore » serious philosophical objections to this assumption and others, such as the assumption that all network nodes undergo affine motion and that all of the network chains have the same length. Recently, a new paradigm for elasticity in rubber networks has been proposed that is based on mechanisms that originate at the molecular level. Using conventional statistical mechanics analyses, quantum chemistry, and molecular dynamics simulations, the fundamental entropic and enthalpic chain extension forces for polyisoprene (natural rubber) have been determined, along with estimates for the basic force constants. Concurrently, the complex morphology of natural rubber networks (the joint probability density distributions that relate the chain end-to-end distance to its contour length) has also been captured in a numerical model. When molecular chain forces are merged with the network structure in this model, it is possible to study the mechanical response to tensile and compressive strains of a representative volume element of a polymer network. As strain is imposed on a network, pathways of connected taut chains, that completely span the network along strain axis, emerge. Although these chains represent only a few percent of the total, they account for nearly all of the elastic stress at high strain. Here we provide

  9. A new paradigm for the molecular basis of rubber elasticity

    NASA Astrophysics Data System (ADS)

    Hanson, David E.; Barber, John L.

    2015-07-01

    The molecular basis for rubber elasticity is arguably the oldest and one of the most important questions in the field of polymer physics. The theoretical investigation of rubber elasticity began in earnest almost a century ago with the development of analytic thermodynamic models, based on simple, highly-symmetric configurations of so-called Gaussian chains, i.e. polymer chains that obey Markov statistics. Numerous theories have been proposed over the past 90 years based on the ansatz that the elastic force for individual network chains arises from the entropy change associated with the distribution of end-to-end distances of a free polymer chain. There are serious conceptual objections to this assumption and others, such as the assumption that all network nodes undergo a simple volume-preserving linear motion and that all of the network chains have the same length. Recently, a new paradigm for elasticity in rubber networks has been proposed that is based on mechanisms that originate at the molecular level. Using conventional statistical mechanics analyses, Quantum Chemistry, and Molecular Dynamics simulations, the fundamental entropic and enthalpic chain extension forces for polyisoprene (natural rubber) have been determined, along with estimates for the basic force constants. Concurrently, the complex morphology of natural rubber networks (the joint probability density distributions that relate the chain end-to-end distance to its contour length) has also been captured in a numerical model (EPnet). When molecular chain forces are merged with the network structure in this model, it is possible to study the mechanical response to tensile and compressive strains of a representative volume element of a polymer network. As strain is imposed on a network, pathways of connected taut chains, that completely span the network along strain axis, emerge. Although these chains represent only a few percent of the total, they account for nearly all of the elastic stress at high

  10. Finite element methods for nonlinear elastostatic problems in rubber elasticity

    NASA Technical Reports Server (NTRS)

    Oden, J. T.; Becker, E. B.; Miller, T. H.; Endo, T.; Pires, E. B.

    1983-01-01

    A number of finite element methods for the analysis of nonlinear problems in rubber elasticity are outlined. Several different finite element schemes are discussed. These include the augmented Lagrangian method, continuation or incremental loading methods, and associated Riks-type methods which have the capability of incorporating limit point behavior and bifurcations. Algorithms for the analysis of limit point behavior and bifurcations are described and the results of several numerical experiments are presented. In addition, a brief survey of some recent work on modelling contact and friction in elasticity problems is given. These results pertain to the use of new nonlocal and nonlinear friction laws.

  11. Mechanistic Constitutive Models for Rubber Elasticity and Viscoelasticity

    SciTech Connect

    Puso, M

    2003-01-21

    Physically based models which describe the finite strain behavior of vulcanized rubber are developed. Constitutive laws for elasticity and viscoelasticity are derived by integrating over orientation space the forces due to each individual polymer chain. A novel scheme is presented which effectively approximates these integrals in terms of strain and strain invariants. In addition, the details involving the implementation of such models into a quasi-static large strain finite element formulation are provided. In order to account for the finite extensibility of a molecular chain, Langevin statistics is used to model the chain response. The classical statistical model of rubber assumes that polymer chains interact only at the chemical crosslinks. It is shown that such model when fitted for uniaxial tension data cannot fit compression or equibiaxial data. A model which incorporates the entanglement interactions of surrounding chains, in addition to the finite extensibility of the chains, is shown to give better predictions than the classical model. The technique used for approximating the orientation space integral was applied to both the classical and entanglement models. A viscoelasticity model based on the force equilibration process as described by Doi and Edwards is developed. An assumed form for the transient force in the chain is postulated. The resulting stress tensor is composed of an elastic and a viscoelastic portion with the elastic stress given by the proposed entanglement model. In order to improve the simulation of experimental data, it was found necessary to include the effect of unattached or dangling polymer chains in the viscoelasticity model. The viscoelastic effect of such chains is the manifestation of a disengagement process. This disengagement model for unattached polymer chains motivated an empirical model which was very successful in simulating the experimental results considered.

  12. Squeeze elastic deformation and contact area of a rubber adhesive

    NASA Astrophysics Data System (ADS)

    Tordjeman, P.; Papon, E.; Villenave, J.-J.

    2000-12-01

    New experimental results show that the tack energy of a nonstringing rubber adhesive is proportional to the square function of the contact area. However, this area seems only to be controlled by the contact force and the thickness of the adhesive. A study of how the contact area depends on physical parameters is of great interest for the modeling of the tack properties of pressure-sensitive adhesives (PSAs). With this objective, we give a mechanical analysis of the tack test in the framework of elasticity. This analysis leads to an analytical expression of force versus thickness of material that is in agreement with the experimental data. Based on this mechanical analysis, a model is proposed to take into account the dependence of the contact area with the contact force and the adhesive thickness. This model is based on the idea that, in confined geometry, the adhesive behaves like an elastic solid and the contact area is a function of the elastic squeeze deformation close to the probe surface. The confrontation with experimental results is good and shows the relevance of this approach. Finally, the model underlines the importance of the roughness, the thickness and the Young's modulus of the adhesive according to the experimental results.

  13. Rubber

    NASA Astrophysics Data System (ADS)

    Graves, D. F.

    The word "rubber" immediately brings to mind materials that are highly flexible and will snap back to their original shape after being stretched. In this chapter a variety of materials are discussed that possess this odd characteristics. There will also be a discussion on the mechanism of this "elastic retractive force." Originally, rubber meant the gum collected from a tree growing in Brazil. The term "rubber" was coined for this material by the English chemist Joseph Priestley, who noted that it was effective for removing pencil marks from paper. Today, in addition to Priestley's natural product, many synthetic materials are made that possess these characteristics and many other properties. The common features of these materials are that they are made up of long-chain molecules that are amorphous (not crystalline), and the chains are above their glass transition temperature at room temperature.

  14. The molecular kink paradigm for rubber elasticity: Numerical simulations of explicit polyisoprene networks at low to moderate tensile strains

    NASA Astrophysics Data System (ADS)

    Hanson, David E.

    2011-08-01

    Based on recent molecular dynamics and ab initio simulations of small isoprene molecules, we propose a new ansatz for rubber elasticity. We envision a network chain as a series of independent molecular kinks, each comprised of a small number of backbone units, and the strain as being imposed along the contour of the chain. We treat chain extension in three distinct force regimes: (Ia) near zero strain, where we assume that the chain is extended within a well defined tube, with all of the kinks participating simultaneously as entropic elastic springs, (II) when the chain becomes sensibly straight, giving rise to a purely enthalpic stretching force (until bond rupture occurs) and, (Ib) a linear entropic regime, between regimes Ia and II, in which a force limit is imposed by tube deformation. In this intermediate regime, the molecular kinks are assumed to be gradually straightened until the chain becomes a series of straight segments between entanglements. We assume that there exists a tube deformation tension limit that is inversely proportional to the chain path tortuosity. Here we report the results of numerical simulations of explicit three-dimensional, periodic, polyisoprene networks, using these extension-only force models. At low strain, crosslink nodes are moved affinely, up to an arbitrary node force limit. Above this limit, non-affine motion of the nodes is allowed to relax unbalanced chain forces. Our simulation results are in good agreement with tensile stress vs. strain experiments.

  15. The effect of elastic modulus and friction coefficient on rubber tube sealing performance

    NASA Astrophysics Data System (ADS)

    Li, Zhimiao; Xu, Siyuan; Ren, Fushen; Liu, Jubao

    2015-03-01

    The packer is the key element in separating geosphere layers of water injection, water plugging and fracturing operations in the oilfield. The sealing ability of the packer is depending on the contact pressure between rubber tube and the casing. The circumferential strain of casing wall was tested by the strain gauge to get the contact pressure distribution along axial direction of the tube. The friction force between the casing and the rubber tube was taken by the pressure sensor in compression process. Under the 20,60 and 100 degrees Celsius conditions, the friction forces and the contact pressure distribution were taken in work condition of single rubber tube, double rubber tubes and combination rubber tubes after oil immersion .The result shows that elastic modulus of rubber tube has little effect on the friction force and contact pressure. With elastic modulus decreasing, the friction forces has gradually decreasing trend; The friction coefficient has much impact on friction force: the friction forces under the condition of dry friction and wet friction are respectively equivalent to 48.27% and 5.38% axial compression forces. At wet friction condition, the contact pressure distribution is more uniform and the sealing effect is better.

  16. Rubber.

    ERIC Educational Resources Information Center

    Krishen, Anoop

    1989-01-01

    This review covers methods for identification, characterization, and determination of rubber and materials in rubber. Topics include: general information, nuclear magnetic resonance spectroscopy, infrared spectroscopy, thermal methods, gel permeation chromatography, size exclusion chromatography, analysis related to safety and health, and…

  17. Rubber elasticity for percolation network consisting of Gaussian chains

    NASA Astrophysics Data System (ADS)

    Nishi, Kengo; Noguchi, Hiroshi; Sakai, Takamasa; Shibayama, Mitsuhiro

    2015-11-01

    A theory describing the elastic modulus for percolation networks of Gaussian chains on general lattices such as square and cubic lattices is proposed and its validity is examined with simulation and mechanical experiments on well-defined polymer networks. The theory was developed by generalizing the effective medium approximation (EMA) for Hookian spring network to Gaussian chain networks. From EMA theory, we found that the ratio of the elastic modulus at p, G to that at p = 1, G0, must be equal to G/G0 = (p - 2/f)/(1 - 2/f) if the position of sites can be determined so as to meet the force balance, where p is the degree of cross-linking reaction. However, the EMA prediction cannot be applicable near its percolation threshold because EMA is a mean field theory. Thus, we combine real-space renormalization and EMA and propose a theory called real-space renormalized EMA, i.e., REMA. The elastic modulus predicted by REMA is in excellent agreement with the results of simulations and experiments of near-ideal diamond lattice gels.

  18. Rubber Elasticity for percolation network consisting of Gaussian Chains

    NASA Astrophysics Data System (ADS)

    Nishi, Kengo; Shibayama, Mitsuhiro; Sakai, Takamasa

    A theory describing the elastic modulus for percolation networks of Gaussian chains on general lattices such as square and cubic lattices is proposed and its validity is examined with simulation and mechanical experiments on well-defined polymer networks. The theory was developed by generalizing the effective medium approximation for Hookian spring network (EMA) to Gaussian chain networks. From EMA theory, we found that the ratio of the elastic modulus at p, G to that at p = 1 ,G0, must be equal to G /G0 = (p - 2 / f) / (1 - 2 / f) if the position of sites can be determined so as to meet the force balance, where p is the degree of cross-linking reaction. However, the EMA prediction cannot be applicable near its percolation threshold because EMA is a mean field theory. Thus, we combine real-space renormalization and EMA, and propose a theory called real-space renormalized EMA, i.e., REMA. The elastic modulus predicted by REMA is in excellent agreement with the results of simulations and experiments of near-ideal diamond lattice gels.

  19. Rubber elasticity for percolation network consisting of Gaussian chains

    SciTech Connect

    Nishi, Kengo E-mail: sakai@tetrapod.t.u-tokyo.ac.jp Noguchi, Hiroshi; Shibayama, Mitsuhiro E-mail: sakai@tetrapod.t.u-tokyo.ac.jp; Sakai, Takamasa E-mail: sakai@tetrapod.t.u-tokyo.ac.jp

    2015-11-14

    A theory describing the elastic modulus for percolation networks of Gaussian chains on general lattices such as square and cubic lattices is proposed and its validity is examined with simulation and mechanical experiments on well-defined polymer networks. The theory was developed by generalizing the effective medium approximation (EMA) for Hookian spring network to Gaussian chain networks. From EMA theory, we found that the ratio of the elastic modulus at p, G to that at p = 1, G{sub 0}, must be equal to G/G{sub 0} = (p − 2/f)/(1 − 2/f) if the position of sites can be determined so as to meet the force balance, where p is the degree of cross-linking reaction. However, the EMA prediction cannot be applicable near its percolation threshold because EMA is a mean field theory. Thus, we combine real-space renormalization and EMA and propose a theory called real-space renormalized EMA, i.e., REMA. The elastic modulus predicted by REMA is in excellent agreement with the results of simulations and experiments of near-ideal diamond lattice gels.

  20. Rubber elasticity for percolation network consisting of Gaussian chains.

    PubMed

    Nishi, Kengo; Noguchi, Hiroshi; Sakai, Takamasa; Shibayama, Mitsuhiro

    2015-11-14

    A theory describing the elastic modulus for percolation networks of Gaussian chains on general lattices such as square and cubic lattices is proposed and its validity is examined with simulation and mechanical experiments on well-defined polymer networks. The theory was developed by generalizing the effective medium approximation (EMA) for Hookian spring network to Gaussian chain networks. From EMA theory, we found that the ratio of the elastic modulus at p, G to that at p = 1, G0, must be equal to G/G0 = (p - 2/f)/(1 - 2/f) if the position of sites can be determined so as to meet the force balance, where p is the degree of cross-linking reaction. However, the EMA prediction cannot be applicable near its percolation threshold because EMA is a mean field theory. Thus, we combine real-space renormalization and EMA and propose a theory called real-space renormalized EMA, i.e., REMA. The elastic modulus predicted by REMA is in excellent agreement with the results of simulations and experiments of near-ideal diamond lattice gels. PMID:26567682

  1. Control of the low-frequency vibrations of elastic metamaterial shafts with discretized arc-rubber layers

    NASA Astrophysics Data System (ADS)

    Lixia, Li; Anjiang, Cai

    2016-06-01

    We propose a new kind of elastic metamaterial (EM) shaft with discretized arc-shaped rubber layers, which shows excellent low-frequency vibration properties. The band gaps of the shaft structure were analyzed by employing the finite element method. The proposed EM shaft exhibits much lower band gaps than the corresponding structures with the whole rubber ring. Furthermore, the band gaps can be modulated by tuning the arc angle and the number of the arc-shaped rubbers. Additionally, we observed that the first complete band gap tends to disappear when the arc angle of each arc-shaped rubber section is decreased but the arc number remains fixed because the arc angle more strongly affects the rotational stiffness than the transverse stiffness of the rubber layers. This new type of EM shafts could find potential application as a means to control the low-frequency vibrations of rotor shafts in mechanical engineering.

  2. Analysis of adhesive elastic contact between a silica glass lens and silicone rubber using the JKR theory

    NASA Astrophysics Data System (ADS)

    Baek, Dooyoung; Hemthavy, Pasomphone; Takahashi, Kunio

    2014-08-01

    Contact between a silica glass lens and silicone rubber is experimentally investigated by simultaneously measuring displacement, force and contact radius. The relationship between these three parameters is derived using elastic theory. The discrepancy between the theoretical relationship and the experimental results is observed to increase as the deformation of the silicone rubber increases. Under smaller deformation conditions, the elastic theory shows good agreement with the experimental results, although infinite stress on the edge of the contact area is predicted in the theory, and time dependence and adhesion hysteresis are observed in all experiments. It is suggested that time dependence and adhesion hysteresis in contact are not induced by the deformation of the bulk of the silicone rubber, but are induced by surface effects. The result suggests that the applicability limit of the elastic theory must be carefully considered in the JKR analysis of point contact for polymers.

  3. Using Rubber-Elastic Material-Ideal Gas Analogies To Teach Introductory Thermodynamics. Part I: Equations of State.

    ERIC Educational Resources Information Center

    Smith, Brent

    2002-01-01

    Describes equations of state as a supplement to an introductory thermodynamics undergraduate course. Uses rubber-elastic materials (REM) which have strong analogies to the concept of an ideal gas and explains the molar basis of REM. Provides examples of the analogies between ideal gas and REM and mathematical analogies. (Contains 22 references.)…

  4. Using Rubber-Elastic Material-Ideal Gas Analogies To Teach Introductory Thermodynamics. Part II: The Laws of Thermodynamics.

    ERIC Educational Resources Information Center

    Smith, Brent

    2002-01-01

    Describes the laws of thermodynamics as a supplement to an introductory thermodynamics undergraduate course. Uses rubber-elastic materials (REM) which have strong analogies to the concept of ideal gas. Provides examples of the analogies between ideal gas and REM and mathematical analogies. (YDS)

  5. Rejuvenation of metallic glasses by non-affine thermal strain.

    PubMed

    Ketov, S V; Sun, Y H; Nachum, S; Lu, Z; Checchi, A; Beraldin, A R; Bai, H Y; Wang, W H; Louzguine-Luzgin, D V; Carpenter, M A; Greer, A L

    2015-08-13

    When a spatially uniform temperature change is imposed on a solid with more than one phase, or on a polycrystal of a single, non-cubic phase (showing anisotropic expansion-contraction), the resulting thermal strain is inhomogeneous (non-affine). Thermal cycling induces internal stresses, leading to structural and property changes that are usually deleterious. Glasses are the solids that form on cooling a liquid if crystallization is avoided--they might be considered the ultimate, uniform solids, without the microstructural features and defects associated with polycrystals. Here we explore the effects of cryogenic thermal cycling on glasses, specifically metallic glasses. We show that, contrary to the null effect expected from uniformity, thermal cycling induces rejuvenation, reaching less relaxed states of higher energy. We interpret these findings in the context that the dynamics in liquids become heterogeneous on cooling towards the glass transition, and that there may be consequent heterogeneities in the resulting glasses. For example, the vibrational dynamics of glassy silica at long wavelengths are those of an elastic continuum, but at wavelengths less than approximately three nanometres the vibrational dynamics are similar to those of a polycrystal with anisotropic grains. Thermal cycling of metallic glasses is easily applied, and gives improvements in compressive plasticity. The fact that such effects can be achieved is attributed to intrinsic non-uniformity of the glass structure, giving a non-uniform coefficient of thermal expansion. While metallic glasses may be particularly suitable for thermal cycling, the non-affine nature of strains in glasses in general deserves further study, whether they are induced by applied stresses or by temperature change. PMID:26268190

  6. Pre-Yield Non-Affine Fluctuations and A Hidden Critical Point in Strained Crystals

    PubMed Central

    Das, Tamoghna; Ganguly, Saswati; Sengupta, Surajit; Rao, Madan

    2015-01-01

    A crystalline solid exhibits thermally induced localised non-affine droplets in the absence of external stress. Here we show that upon an imposed shear, the size of these droplets grow until they percolate at a critical strain, well below the value at which the solid begins to yield. This critical point does not manifest in most thermodynamic or mechanical properties, but is hidden and reveals itself in the onset of inhomogeneities in elastic moduli, marked changes in the appearance and local properties of non-affine droplets and a sudden enhancement in defect pair concentration. Slow relaxation of stress and an-elasticity appear as observable dynamical consequences of this hidden criticality. Our results may be directly verified in colloidal crystals with video microscopy techniques but are expected to have more general validity. PMID:26039380

  7. Rubber and gel origami: visco- and poro-elastic behavior of folded structures

    NASA Astrophysics Data System (ADS)

    Evans, Arthur; Bende, Nakul; Na, Junhee; Hayward, Ryan; Santangelo, Christian

    2014-11-01

    The Japanese art of origami is rapidly becoming a platform for material design, as researchers develop systematic methods to exploit the purely geometric rules that allow paper to folded without stretching. Since any thin sheet couples mechanics strongly to geometry, origami provides a natural template for generating length-scale independent structures from a variety of different materials. In this talk I discuss some of the implications of using polymeric sheets and shells over many length scales to create folded materials with tunable shapes and properties. These implications include visco-elastic snap-through transitions and poro-elastically driven micro origami. In each case, mechanical response, dynamics, and reversible folding is tuned through a combination of geometry and constitutive properties, demonstrating the efficacy of using origami principles for designing functional materials.

  8. Nonlinear force propagation, anisotropic stiffening and non-affine relaxation in a model cytoskeleton

    NASA Astrophysics Data System (ADS)

    Mizuno, Daisuke; Head, David; Ikebe, Emi; Nakamasu, Akiko; Kinoshita, Suguru; Peijuan, Zhang; Ando, Shoji

    2013-03-01

    Forces are generated heterogeneously in living cells and transmitted through cytoskeletal networks that respond highly non-linearly. Here, we carry out high-bandwidth passive microrheology on vimentin networks reconstituted in vitro, and observe the nonlinear mechanical response due to forces propagating from a local source applied by an optical tweezer. Since the applied force is constant, the gel becomes equilibrated and the fluctuation-dissipation theorem can be employed to deduce the viscoelasticity of the local environment from the thermal fluctuations of colloidal probes. Our experiments unequivocally demonstrate the anisotropic stiffening of the cytoskeletal network behind the applied force, with greater stiffening in the parallel direction. Quantitative agreement with an affine continuum model is obtained, but only for the response at certain frequency ~ 10-1000 Hz which separates the high-frequency power law and low-frequency elastic behavior of the network. We argue that the failure of the model at lower frequencies is due to the presence of non-affinity, and observe that zero-frequency changes in particle separation can be fitted when an independently-measured, empirical nonaffinity factor is applied.

  9. Tough Rubber.

    ERIC Educational Resources Information Center

    Schmid, Sue

    1994-01-01

    Describes the benefits of using rubber floor coverings in a gym's free-weight and cardiovascular equipment areas. Tips on purchasing a rubber floor are highlighted as is an annotated list of suppliers and their rubber flooring products. (GR)

  10. Rubber linings answer to many problems

    SciTech Connect

    Mehra, L.

    1998-12-31

    The uses of rubber linings in different fields industries are discussed.The physical properties of rubber both natural and synthetic rubber are listed and their importance is evaluated. The aging of rubber is discussed in detail, including effects of temperature on aging of rubber. By virtue of its inherent elasticity and chemical resistance, rubber linings have found many uses in the protection of mining equipment, water treatment tanks and vessels, flue gas desulfurization equipment in power plants and varied process and storage vessels in chemical industries. Rubber has found extensive use in civil engineering field as expansion joints and bladders in dams. Electrical resistance of rubber is useful for its application as an insulating material. Rubber is chemically resistant to acids, alkalies and many salt solutions. Rubber linings are therefore used for protection of steel against these acids, alkalies or salt solutions. The extreme elasticity of rubber has been found useful in its application as a lining material in areas subject to high abrasion. Frequently rubber linings are the linings of choice when a combination of abrasion and chemical attack are to be protected against. Constantly, new formulations of rubber lining compounds are being developed just as new chemical processes are being made. The flexibility of compounding and the relative ease of putting layers of different rubber formulations together in multilayered formulations of rubber lining compounds is leading to new uses of this lining material.

  11. Elastic protectors for ultrasound injection

    SciTech Connect

    Barkhatov, V.A.; Nesterova, L.A.

    1995-07-01

    A new material has been developed for elastic protectors on ultrasonic probes: sonar rubber. This combines low ultrasonic absorption, high strength, and wear resistance, and so the rubber can be used in sensor designs.

  12. Importance of non-affine viscoelastic response in disordered fibre networks.

    PubMed

    Rizzi, L G; Auer, S; Head, D A

    2016-05-11

    Disordered fibre networks are ubiquitous in nature and have a wide range of industrial applications as novel biomaterials. Predicting their viscoelastic response is straightforward for affine deformations that are uniform over all length scales, but when affinity fails, as has been observed experimentally, modelling becomes challenging. Here we present a numerical methodology, related to an existing framework for amorphous packings, to predict the steady-state viscoelastic spectra and degree of affinity for disordered fibre networks driven at arbitrary frequencies. Applying this method to a peptide gel model reveals a monotonic increase of the shear modulus as the soft, non-affine normal modes are successively suppressed as the driving frequency increases. In addition to being dominated by fibril bending, these low frequency network modes are also shown to be delocalised. The presented methodology provides insights into the importance of non-affinity in the viscoelastic response of peptide gels, and is easily extendible to all types of fibre networks. PMID:27079274

  13. Rubber Reclamation

    ERIC Educational Resources Information Center

    Williams, Kathryn R.

    2007-01-01

    The safety and health hazards related to recycling of used rubber, due to the scarcity and high price of virgin rubber are reported. Various threats like stagnant water pools trapped in tires leading to diseases and ignited tires, which become very difficult to extinguish and generating smoke that is extremely detrimental to the environment, have…

  14. Non-affine fluctuations and the statistics of defect precursors in the planar honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Mitra, Amartya; Ganguly, Saswati; Sengupta, Surajit; Sollich, Peter

    2015-06-01

    Certain localised displacement fluctuations in the planar honeycomb lattice may be identified as precursors to topological defects. We show that these fluctuations are among the most pronounced non-affine distortions of an elemental coarse graining volume of the honeycomb structure at non zero temperatures. We obtain the statistics of these precursor modes in the canonical ensemble, evaluating exactly their single point and two-point spatio-temporal distributions, for a lattice with harmonic nearest neighbour and next near neighbour bonds. As the solid is destabilised by tuning interactions, the precursor fluctuations diverge and correlations become long-lived and long-ranged.

  15. How far can a rubber molecule stretch before breaking? Ab initio study of tensile elasticity and failure in single-molecule polyisoprene and polybutadiene

    NASA Astrophysics Data System (ADS)

    Hanson, David E.; Martin, Richard L.

    2009-02-01

    We present ab initio calculations of the internal C-C bond dissociation curve for single molecules of (cis-1,4) polyisoprene and polybutadiene. We define "bond rupture" as that point on the reaction coordinate where the unrestricted Kohn-Sham, or diradical, solution falls below the restricted, or closed-shell, solution. Using this definition, we find that rupture occurs at a tensile force of 6.8 nN for polyisoprene and 7.2 nN for polybutadiene. Their respective rupture strains are 45% and 42%. Our calculations show that the energy density versus extension is not sensitive to the number of isoprene units contained in the molecule, i.e., it is essentially independent of the chain length. These relatively large rupture strains have important implications for understanding the failure mechanism in rubber, and imply that purely enthalpic chain stretching must commence well before tensile failure occurs.

  16. Non-affinity factors modulating vascular targeting of nano- and microcarriers.

    PubMed

    Myerson, Jacob W; Anselmo, Aaron C; Liu, Yaling; Mitragotri, Samir; Eckmann, David M; Muzykantov, Vladimir R

    2016-04-01

    Particles capable of homing and adhering to specific vascular biomarkers have potential as fundamental tools in drug delivery for mediation of a wide variety of pathologies, including inflammation, thrombosis, and pulmonary disorders. The presentation of affinity ligands on the surface of a particle provides a means of targeting the particle to sites of therapeutic interest, but a host of other factors come into play in determining the targeting capacity of the particle. This review presents a summary of several key considerations in nano- and microparticle design that modulate targeted delivery without directly altering epitope-specific affinity. Namely, we describe the effect of factors in definition of the base carrier (including shape, size, and flexibility) on the capacity of carriers to access, adhere to, and integrate in target biological milieus. Furthermore, we present a summary of fundamental dynamics of carrier behavior in circulation, taking into account interactions with cells in circulation and the role of hemodynamics in mediating the direction of carriers to target sites. Finally, we note non-affinity aspects to uptake and intracellular trafficking of carriers in target cells. In total, recent findings presented here may offer an opportunity to capitalize on mitigating factors in the behavior of ligand-targeted carriers in order to optimize targeting. PMID:26596696

  17. Early-time particle dynamics and non-affine deformations during microstructure selection in solids

    NASA Astrophysics Data System (ADS)

    Sengupta, Surajit; Rao, Madan; Bhattacharya, Jayee

    2011-07-01

    Solid-solid transitions are invariably associated with groups of particles whose deformations cannot be expressed as an affine strain about a reference configuration. The dynamics of these non-affine zones (NAZ) determine the subsequent microstructure, i.e. the mesoscale patterning resulting from the structural transition. Here, we focus on early-time dynamics of individual particles within an NAZ associated with a nucleation event. We show that the early-time behavior of these particles have distinctive characteristics depending on the transition temperature. The dynamics is heterogeneous, consisting of a few active particles exhibiting complex intermittent jamming and flow in response to internal stresses generated during the transformation. At low temperatures, the dynamics of these active particles is ballistic and the structural transformation proceeds via string-like correlated movement of active particles, along ridges in the potential energy topography set up by inactive particles. On increasing temperature, the dynamics of active particles show an abrupt transition from ballistic to diffusive behavior with a diffusion coefficient which appears to be independent of temperature. This dynamical transition in the nature of the trajectories of particles is coincident with a discontinuous transition in the microstructure of the solid. Finally, we characterize this transition in terms of a dynamical order parameter in the space of trajectories and discuss its connection with the glass transition and rheology of soft and granular matter.

  18. How far can a rubber molecule stretch before breaking? Ab initio study of tensile elasticity and failure in single-molecule polyisoprene

    SciTech Connect

    Hanson, David E

    2008-01-01

    We present ab initio calculations of the internal C-C bond dissociation curve for single molecules of (cis 1,4) polyisoprene, polybutadiene, and polyethylene, all of comparable length. We define 'bond rupture' as that point on the reaction coordinate where the unrestricted Kohn-Sham, or diradical, solution falls below the restricted, or closed-shell, solution. Using this well-defined though crude approximation, we find that rupture occurs at a tensile force of 6.8 nN for poly isoprene and 7.2 nN for polybutadiene. Their respective rupture strains are 45% and 42%. Our calculations show that the energy density vs. extension is not sensitive to the length of the molecule, i.e., it is essentially independent of the number of isoprene units contained. These relatively large rupture strains have important implications for understanding the failure mechanism in rubber, and imply that purely enthalpic chain stretching must commence well before tensile failure occurs.

  19. Stress-strain determination in rubber-cord and rubber-metal structures by the frozen inset method

    NASA Astrophysics Data System (ADS)

    Ushakov, B. N.; Tartakover, E. I.

    1996-06-01

    The new experimental method for determination of stresses inside of real rubber, rubber-cord and rubber-metal structures using frozen insets and photoelasticity is considered. This method is based on analogy between the elasticity and viscoelasticity problems for polymers during polymerization. The photoelastic materials of cold polymerization for insets making are developed and testing technology is reported. The results of stress analysis in automobile tires under interior pressure and radial loads are presented.

  20. Reinforcement Effect of Corn Flour in Rubber Composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn flour is an economical renewable material and investigated in this study as filler for rubber composites. The composites were prepared by mixing an aqueous dispersion of corn flour with rubber latex, followed by freeze-drying and compression molding. The small strain elastic modulus and the str...

  1. The Functional Identification of Rubber Biosynthetic Genes in Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (cis-1,4-polyisoprene) is an essential plant derived raw material required for the manufacture of numerous industrial and medical related products. This elastic polymer is synthesized and sequestered within cytosolic vesicles known as rubber particles. When provided with farnesyl-pyro...

  2. Burning rubber

    SciTech Connect

    Not Available

    1987-09-01

    Mario Andretti, look out You are about to be surpassed in the burning rubber category by a joint venture between Oxford Energy Company and General Electric. The two companies are building the first whole tire-to-energy facility in the US in Modesto, California. This $41 million facility does not require tires to be shredded prior to incineration; it has the capacity to burn 700 tires per minute. The electricity generated will be provided to a utility company. Oxford says there are two billion waste tires on the ground and this number is increasing by 220 million a year. Of that amount, only 18 million a year are recycled.

  3. Thermoviscoplastic behaviors of anisotropic shape memory elastomeric composites for cold programmed non-affine shape change

    NASA Astrophysics Data System (ADS)

    Mao, Yiqi; Robertson, Jaimee M.; Mu, Xiaoming; Mather, Patrick T.; Jerry Qi, H.

    2015-12-01

    Shape memory polymers (SMPs) can fix a temporary shape and recover their permanent shape upon activation by an external stimulus. Most SMPs require programming at above their transition temperatures, normally well above the room temperature. In addition, most SMPs are programmed into shapes that are affine to the high temperature deformation. Recently, a cold-programmed anisotropic shape memory elastomeric composite was developed and showed interesting low temperature stretching induced shape memory behavior. There, simple, uniaxial stretching at low temperature transformed the composites into curled temporary shapes upon unloading. The exact geometry of the curled state depended on the microstructure of the composite, and the curled shape showed no affinity to the deformed shape. Heating the sample recovered the sample back to its original shape. This new composite consisted of an elastomeric matrix reinforced by aligned amorphous polymer fibers. By utilizing the plastic-like behavior of the amorphous polymer phase at low temperatures, a temporary shape could be fixed upon unloading since the induced plastic-like strain resists the recovery of the elastomer matrix. After heating to a high temperature, the permanent shape was recovered when the amorphous polymer softened and the elastomer matrix contracted. To set a theoretical foundation for capturing the cold-programmed shape memory effects and the dramatic non-affine shape change of this composite, a 3D anisotropic thermoviscoelastic constitutive model is developed in this paper. In this model, the matrix is modeled as a hyperelastic solid, and the amorphous phase of the fibrous mat is considered as a nonlinear thermoviscoplastic solid, whose viscous flow resistance is sensitive to both temperature and stress. The plastic-deformation like behavior demonstrated in the fiber is treated as nonlinear viscoplasticity with extremely high viscosity or long relaxation time at zero-stress state at low temperature. The

  4. Elastic and Inelastic Collisions

    ERIC Educational Resources Information Center

    Gluck, Paul

    2010-01-01

    There have been two articles in this journal that described a pair of collision carts used to demonstrate vividly the difference between elastic and inelastic collisions. One cart had a series of washers that were mounted rigidly on a rigid wooden framework, the other had washers mounted on rubber bands stretched across a framework. The rigidly…

  5. On the response of rubbers at high strain rates.

    SciTech Connect

    Niemczura, Johnathan Greenberg

    2010-02-01

    In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in the rubber strips. Analysis of the response through the theory of finite waves and quantitative matching between the experimental observations and analytical predictions was used to determine an appropriate instantaneous elastic response for the rubbers. This analysis also yields the tensile shock adiabat for rubber. Dispersive waves as well as shock waves are also observed in free-retraction experiments; these are used to quantify hysteretic effects in rubber.

  6. Stimuli-responsive cement-reinforced rubber.

    PubMed

    Musso, Simone; Robisson, Agathe; Maheshwar, Sudeep; Ulm, Franz-Josef

    2014-05-14

    In this work, we report the successful development of a cement-rubber reactive composite with reversible mechanical properties. Initially, the composite behaves like rubber containing inert filler, but when exposed to water, it increases in volume and reaches a stiffness that is intermediate between that of hydrogenated nitrile butadiene rubber (HNBR) and hydrated cement, while maintaining a relatively large ductility characteristic of rubber. After drying, the modulus increases even further up to 400 MPa. Wet/drying cycles prove that the elastic modulus can reversibly change between 150 and 400 MPa. Utilizing attenuated total reflection Fourier transform infrared spectroscopy), we demonstrate that the high pH produced by the hydration of cement triggers the hydrolysis of the rubber nitrile groups into carboxylate anions. Thus, the salt bridges, generated between the carboxylate anions of the elastomer and the cations of the filler, are responsible for the reversible variations in volume and elastic modulus of the composite as a consequence of environmental moisture exposure. These results reveal that cement nanoparticles can successfully be used to accomplish a twofold task: (a) achieve an original postpolymerization modification that allows one to work with carboxylate HNBR (HXNBR) not obtained by direct copolymerization of carboxylate monomers with butadiene, and (b) synthesize a stimuli-responsive polymeric composite. This new type of material, having an ideal behavior for sealing application, could be used as an alternative to cement for oil field zonal isolation applications. PMID:24734968

  7. Vulcanization and the mechanical response of rubber

    NASA Astrophysics Data System (ADS)

    Kundurthi, S.; Mythravaruni, P.; Ravindran, P.

    2015-06-01

    Hyperelastic models are widely used to describe the mechanical response of rubber. However, purely mechanical models cannot account for changes in the material due to chemical reactions such as those that take place during vulcanization. Here, we present a model developed within a thermodynamic framework accounting for chemical reactions. A mixture theory approach that allows for the existence of multiple species and their interconversion is followed. The existence of a Helmholtz potential and a rate of entropy production function for the mixture as a whole are posited. Following the multiple natural configuration approach, the rate of entropy production is maximized to obtain constitutive equations. The viscoelastic model is then specialized to the elastic case. The model is calibrated using data available in the literature for rubber. A simulation of the stress-strain curve of rubber as vulcanization progresses is presented.

  8. Another Demo of the Unusual Thermal Properties of Rubber

    NASA Astrophysics Data System (ADS)

    Liff, Mark I.

    2010-10-01

    The unusual thermal behavior of rubbers, though discovered a long time ago, can still be mind-boggling for students and teachers who encounter this class of polymeric systems. Unlike other solids, stretched elastic polymers shrink upon heating. This is a manifestation of the Gough-Joule (G-J) effect.1-4 Joule in the 1850s studied the thermal behavior of rubbers that was initially explored by Gough in 1805. Properties of rubbers such as contraction upon heating, or the related phenomenon of heating upon fast expansion, did not make much sense at that time. Joule's work validated Gough's results, but the molecular basis of the unusual thermal behavior of rubbers remained unexplained for another 70 years. The physical ideas, taking into account gigantic conformational entropy of elastic polymers that explain their contraction on heating, were developed by Staudinger, Kuhn, and others only in the 1920s and 1930s.5

  9. Robust adaptive control for a class of uncertain non-affine nonlinear systems using affine-type neural networks

    NASA Astrophysics Data System (ADS)

    Zhao, Shitie; Gao, Xianwen

    2016-08-01

    A robust adaptive control is proposed for a class of single-input single-output non-affine nonlinear systems. In order to approximate the unknown nonlinear function, a novel affine-type neural network is used, and then to compensate the approximation error and external disturbance a robust control term is employed. By Lyapunov stability analysis for the closed-loop system, it is proved that tracking errors asymptotically converge to zero. Moreover, an observer is designed to estimate the system states because all the states may not be available for measurements. Furthermore, the adaptation laws of neural networks and the robust controller are given out based on the Lyapunov stability theory. Finally, two simulation examples are presented to demonstrate the effectiveness of the proposed control method.

  10. Nonaqueous ozonation of vulcanized rubber

    SciTech Connect

    Serkiz, S.M.

    1999-12-07

    A process and resulting product are provided in which a solid particulate, such as vulcanized crumb rubber, has the surface functional groups oxidized by ozonation using a nonpolar solvent. The ozonation process renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels of the treated crumb rubber can be used in new rubber mixtures.

  11. Nonaqueous ozonation of vulcanized rubber

    DOEpatents

    Serkiz, Steven M.

    1999-01-01

    A process and resulting product is provided in which a solid particulate, such as vulcanized crumb rubber, has the surface functional groups oxidized by ozonation using a nonpolar solvent. The ozonation process renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels of the treated crumb rubber can be used in new rubber mixtures.

  12. Mechanism of Resilin Elasticity

    PubMed Central

    Qin, Guokui; Hu, Xiao; Cebe, Peggy; Kaplan, David L.

    2012-01-01

    Resilin is critical in the flight and jumping systems of insects as a polymeric rubber-like protein with outstanding elasticity. However, insight into the underlying molecular mechanisms responsible for resilin elasticity remains undefined. Here we report the structure and function of resilin from Drosophila CG15920. A reversible beta-turn transition was identified in the peptide encoded by exon III and for full length resilin during energy input and release, features that correlate to the rapid deformation of resilin during functions in vivo. Micellar structures and nano-porous patterns formed after beta-turn structures were present via changes in either the thermal or mechanical inputs. A model is proposed to explain the super elasticity and energy conversion mechanisms of resilin, providing important insight into structure-function relationships for this protein. Further, this model offers a view of elastomeric proteins in general where beta-turn related structures serve as fundamental units of the structure and elasticity. PMID:22893127

  13. Elastic activator for treatment of open bite.

    PubMed

    Stellzig, A; Steegmayer-Gilde, G; Basdra, E K

    1999-06-01

    This article presents a modified activator for treatment of open bite cases. The intermaxillary acrylic of the lateral occlusal zones is replaced by elastic rubber tubes. By stimulating orthopaedic gymnastics (chewing gum effect), the elastic activator intrudes upper and lower posterior teeth. A noticeable counterclockwise rotation of the mandible was accomplished by a decrease of the gonial angle. Besides the simple fabrication of the device and uncomplicated replacement of the elastic rubber tubes, treatment can be started even in mixed dentition when affixing plates may be difficult. PMID:10420241

  14. Finite element analysis on the fracture of rubber toughened polymer blends

    SciTech Connect

    Wu, Y.; Mai, Y.W.; Wu, J.

    1997-12-31

    The effect of rubber particle volume fraction on the constitutive relation and fracture toughness of polymer blends was studied using elastic-plastic Finite Element Analysis (FEA). The effect of rubber particle cavitation on the stress-strain state at a crack tip was also investigated. Stress analysis reveals that because of the high rubber bulk modulus, the hydrostatic stress inside the rubber particle is close to that in the adjacent matrix material element. As a result, the rubber particle imposes a severe plastic constraint to the surrounding matrix and limits its plastic strain. Rubber particle cavitation can effectively release the constraint and enable large scale plastic strain to occur. Different failure criteria were used to determine the optimum rubber particle volume fraction for the polymer blends studied in this paper.

  15. Flow properties of natural rubber composites filled with defatted soy flour

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The linear and nonlinear viscoelastic properties of natural rubber composites reinforced with defatted soy flour were studied. Defatted soy flour is an abundant, renewable commodity, and its rigid nature makes it suitable as a reinforcement phase in rubber composites. At small strain, the elastic ...

  16. Mechanical properties of concrete containing a high volume of tire-rubber particles.

    PubMed

    Khaloo, Ali R; Dehestani, M; Rahmatabadi, P

    2008-12-01

    Due to the increasingly serious environmental problems presented by waste tires, the feasibility of using elastic and flexible tire-rubber particles as aggregate in concrete is investigated in this study. Tire-rubber particles composed of tire chips, crumb rubber, and a combination of tire chips and crumb rubber, were used to replace mineral aggregates in concrete. These particles were used to replace 12.5%, 25%, 37.5%, and 50% of the total mineral aggregate's volume in concrete. Cylindrical shape concrete specimens 15 cm in diameter and 30 cm in height were fabricated and cured. The fresh rubberized concrete exhibited lower unit weight and acceptable workability compared to plain concrete. The results of a uniaxial compressive strain control test conducted on hardened concrete specimens indicate large reductions in the strength and tangential modulus of elasticity. A significant decrease in the brittle behavior of concrete with increasing rubber content is also demonstrated using nonlinearity indices. The maximum toughness index, indicating the post failure strength of concrete, occurs in concretes with 25% rubber content. Unlike plain concrete, the failure state in rubberized concrete occurs gently and uniformly, and does not cause any separation in the specimen. Crack width and its propagation velocity in rubberized concrete are lower than those of plain concrete. Ultrasonic analysis reveals large reductions in the ultrasonic modulus and high sound absorption for tire-rubber concrete. PMID:18372166

  17. Rubber Band Science

    ERIC Educational Resources Information Center

    Cowens, John

    2005-01-01

    Not only are rubber bands great for binding objects together, but they can be used in a simple science experiment that involves predicting, problem solving, measuring, graphing, and experimenting. In this article, the author describes how rubber bands can be used to teach the force of mass.

  18. Failure studies on rubber and rubber composites

    NASA Astrophysics Data System (ADS)

    Tao, Zhenghong

    A research study has been conducted to investigate selected failure processes in rubber and rubbery composites. Specific failure modes and materials considered included mechanical tearing of rubber-coated fabrics and mechanical/thermal fatigue of carbon black-filled elastomers. Experimental efforts developed novel evaluation techniques that were used to access failure resistance of the materials, as well as to elucidate molecular structure/physical properties relationships. Results are presented in multi-monograph format consisting of a series of four interdependent papers published in peer-reviewed journals. The first monograph measures the tear resistance of a series of polyester fabrics, of controlled fill-yarn size, coated with a compounded butyl rubber resin. A constrained trouser tear test is used to quantify the role of yarn mobility on crack-tip development and the resultant tear strength. As the area around a propagating crack is constrained, tear strength decreases by several orders of magnitude, indicating that the ability of the composite structure to dissipate energy away from the crack tip contributes more to tear resistance than the intrinsic strength of the concomitant materials. Monograph number two continues the work of the first by developing a novel cutting technique to monitor the role of the fiber/rubber interphase during tear propagation. This approach was applied to five different elastomers coated onto one of the polyester yarns. These data show a threefold increase in strength is possible by proper optimization of the fiber/rubber bond. In the third monograph, five different rubber bushing compounds were evaluated for mechanical/thermal fatigue resistance. Samples were dynamically excited in combined compression and shear loadings using a specially designed test fixture. Results indicated that heat build-up was a major contributing factor to the eventual failure of the materials via a complex fracture mechanism, with epoxidized natural

  19. Multilayer graphene rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas

    2016-05-01

    Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m2/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development.

  20. US rubber markets recover

    SciTech Connect

    Wood, A.

    1993-02-03

    Synthetic rubber markets in North America bounced back in no uncertain terms last year, with demand climbing an impressive 9.5%, to 2.97 million m.t.; and, according to the International Institute of Synthetic Rubber Producers (IIS-RP; Houston) latest five-year forecast, producers can look forward to a 3.3% increase in demand during 1993. This growth rate outpaced out 1992 forecast and demonstrates the resilience of the synthetic rubber industry, says William E. Tessemer, managing director of IISRP. We expect demand in 1993 to surpass 1992 and level off at a 2%/year growth rate for synthetic rubber - 2.5% including thermoplastic elastomers [TPEs]-over the 1993-97 period. The improvement reflects signs of a recovery in North America, especially the pickup in the auto and tire industry. The two major tire rubbers - styrene butadiene and polybutadiene rubber - notched up double-digit gains, and other materials that have autos uses, such as nitrile rubber and many of the specialty elastomers, also advanced strongly.

  1. Elastic scintillation materials based on polyorganosiloxane

    SciTech Connect

    Grinev, B.V.; Andryushchenko, L.A.; Shershukov, V.M.; Ulanenko, K.B.; Minakova, R.A.; Sevastjanova, I.V.

    1994-12-31

    The developed elastic scintillators based on polymethyl-phenylsiloxane rubber are characterized by an elevated light output and a low toxicity. The increase of their light output is achieved by raising the content of phenyl chains, varying the chemical structure of luminescent additions and using isopropylnaphthalene. This high-boiling solvent introduced into the scintillation siloxane compositions is confined within siloxane matrix after the hardening of the rubber.

  2. Rubber Impact on 3D Textile Composites

    NASA Astrophysics Data System (ADS)

    Heimbs, Sebastian; Van Den Broucke, Björn; Duplessis Kergomard, Yann; Dau, Frederic; Malherbe, Benoit

    2012-06-01

    A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools.

  3. Ericameria Nauseosa (rubber rabbitbrush): a complementary rubber feedstock to augment the guayule rubber production stream

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ericameria nauseosa (rubber rabbitbrush) is a highly prolific desert shrub that produces high quality natural rubber. Over the past several years we have investigated rabbitbrush’s potential as a commercial rubber feedstock. Like guayule, rabbitbrush produces natural rubber within its bark tissues a...

  4. New application of crystalline cellulose in rubber composites

    NASA Astrophysics Data System (ADS)

    Bai, Wen

    Rubber without reinforcement has limited applications. The strength of reinforced rubber composites can be ten times stronger than that of unreinforced rubbers. Therefore, rubber composites are widely used in various applications ranging from automobile tires to seals, valves, and gaskets because of their excellent mechanical elastic properties. Silica and carbon black are the two most commonly used reinforcing materials in rubber tires. They are derived from non-renewable materials and are expensive. Silica also contributes to a large amount of ash when used tires are disposed of by incineration. There is a need for a new reinforcing filler that is inexpensive, renewable and easily disposable. Cellulose is the most abundant natural polymer. Native cellulose includes crystalline regions and amorphous regions. Crystalline cellulose can be obtained by removing the amorphous regions with the acid hydrolysis of cellulose because the amorphous cellulose can be hydrolyzed faster than crystalline cellulose. We recently discovered that the partial replacement of silica with microcrystalline cellulose (MCC) provided numerous benefits: (1) low energy consumption for compounding, (2) good processability, (3) strong tensile properties, (4) good heat resistance, and (5) potential for good fuel efficiency in the application of rubber tires. Strong bonding between fillers and a rubber matrix is essential for imparting rubber composites with the desired properties for many specific applications. The bonding between hydrophilic MCC and the hydrophobic rubber matrix is weak and can be improved by addition of a coupling agent or surface modifications of MCC. In this study, MCC was surface-modified with acryloyl chloride or alkenyl ketene dimer (AnKD) to form acrylated MCC (A-MCC) and AnKD-modified MCC (AnKD-MCC). The surface modifications of MCC did not change the integrity and mechanical properties of MCC, but provided functional groups that were able to form covalent linkages with

  5. The Isolation of Rubber from Milkweed Leaves. An Introductory Organic Chemistry Lab

    NASA Astrophysics Data System (ADS)

    Volaric, Lisa; Hagen, John P.

    2002-01-01

    We present an introductory organic chemistry lab in which students isolate rubber from the leaves of milkweed plants (Asclepias syriaca). Students isolated rubber with a recovery of 2.4 ± 1.8% and 1.8 ± 0.7% for the microscale and macroscale procedures, respectively. Infrared spectra of their products were compared with the spectrum of synthetic rubber, cis-polyisoprene. Students tested for elasticity of their product by twisting it on a spatula and pulling; all students found some degree of elasticity.

  6. Another Demo of the Unusual Thermal Properties of Rubber

    ERIC Educational Resources Information Center

    Liff, Mark I.

    2010-01-01

    The unusual thermal behavior of rubbers, though discovered a long time ago, can still be mind-boggling for students and teachers who encounter this class of polymeric systems. Unlike other solids, stretched elastic polymers shrink upon heating. This is a manifestation of the Gough-Joule (G-J) effect. Joule in the 1850s studied the thermal behavior…

  7. Improved rubber nanofillers

    SciTech Connect

    Boyle, T. J.

    2012-03-01

    During this task, Silane functionalized TiO2 and HK3Ti4O4(SiO4)3 were sent to Goodyear (GY) for testing. These materials were characterized based on their interaction with the model elastomer, squalene. The Van der Waals interactions and Hamaker Constants for ZnO particles in squalene and rubber materials were characterized and it was determined that a 10-20 nm spacing was necessary between primary filler particles to maintain a stable nanocomposite. Contact angle measurements on the ZnO and ZnO-silane materials indicated that the solvent should wet the particles, and solvophobic attractions should not be present. These studies showed that the surface modification with sulfosilane coupling agents was successful, and high levels of dispersion of the particles remained possible. Further, a novel surface charging phenomenon where negative surface charging is developed in the squalene environment was observed and corroborated by measurements of particle size and of the surface modified materials in squalene. This impacts the dispersion of the particles according to the traditional colloidal interpretation of electrostatic repulsive forces between particles. Additionally, thin nanocomposite fibers were developed using electrospinning. The size and shape of the oxides did not change during the electrospinning process, although the shape of the fiber and the distribution of the particles, particularly for ZnO, was not ideal. There was an obvious increase in elastic modulus and hardness from the addition of the oxides, but differentiating the oxides, and particularly the surfactants, was difficult. The A-1289 lead to the greatest dispersion of the filler particles, while the A-1589 and the NXT produced clustered particle aggregates. This agrees with previous study of these materials in low molecular weight squalene solvent studies reported earlier. The behavior of the nanoparticle ZnO and the microparticle silica is different as well, with the ZnO being contained within

  8. Microwave treatment of vulcanized rubber

    DOEpatents

    Wicks, George G.; Schulz, Rebecca L.; Clark, David E.; Folz, Diane C.

    2002-07-16

    A process and resulting product is provided in which a vulcanized solid particulate, such as vulcanized crumb rubber, has select chemical bonds broken by microwave radiation. The direct application of microwaves in combination with uniform heating of the crumb rubber renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger particle sizes and/or loading levels of the treated crumb rubber can be used in new rubber mixtures to produce recycled composite products with good properties.

  9. Epoxy-rubber interactions

    SciTech Connect

    McGarry, F.J.; Rosner, R.B.

    1993-12-31

    Films containing amine-terminated butadiene-acrylonitrile (ATBN) rubber and diglycidal ether of bisphenol A (DGEBA) epoxy, cross-linked with amine curing agent, exhibit tensile extensibility over the composition range of 50-600 parts by weight rubber to 100 parts by weight epoxy. This tensile extensibility suggests the presence of ductile behavior in the second-phase particles of ATBN rubber-toughened DGEBA epoxy systems, even if the particles contain substantial amounts of epoxy. Such cured films also are capable of absorbing large additional amounts of liquid epoxy that contains the cure agent. When the epoxy is cured in situ, the film tensile behavior is consistent with the overall proportions of rubber and epoxy present. The solubility behavior also suggests that the glassy epoxy matrix immediately surrounding a precipated particle contains rubber in solid solution and thereby can plastically yield under shear-stress action. As observations confirm, such flow would be heat recoverable. 15 refs., 9 figs., 2 tabs.

  10. Dermatitis in rubber manufacturing industries

    SciTech Connect

    White, I.R.

    1988-01-01

    This review describes the history of rubber technology and the manufacturing techniques used in rubber manufacturing industries. The important aspects of the acquisition of allergic and irritant contact dermatitis within the industry are presented for the reader.

  11. Effect of processing methods on the mechanical properties of natural rubber filled with stearic acid modified soy protein particles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber was reinforced with stearic acid modified soy protein particles prepared with a microfluidizing and ball milling process. Longer ball milling time tends to increase tensile strength of the rubber composites. Elastic modulus of the composites increased with the increasing filler concen...

  12. Elastin-Based Rubber-Like Hydrogels.

    PubMed

    Desai, Malav S; Wang, Eddie; Joyner, Kyle; Chung, Tae Won; Jin, Hyo-Eon; Lee, Seung-Wuk

    2016-07-11

    We developed rubber-like elastomeric materials using a natural elastin derived sequence and genetic engineering to create precisely defined elastin-like polypeptides. The coiled elastin-like polypeptide chains, which behave like entropic springs, were cross-linked using an end-to-end tethering scheme to synthesize simple hydrogels with excellent extensibility and reversibility. Our hydrogels extend to strains as high as 1500% and remain highly resilient with elastic recovery as high as 94% even at 600% strain, significantly exceeding any other protein-based hydrogel. These materials are valuable as elastomeric hydrogels for designing extremely robust scaffolds useful for tissue engineering. PMID:27257908

  13. Application of asphalt rubber technology to recreational trails

    NASA Astrophysics Data System (ADS)

    Ni, Haifeng

    Crumb rubber aggregate was employed instead of stone/sand aggregate in asphalt pavement that was modified by fine rubber particles. Crumb rubber aggregate forms an elastic network in the asphalt, which improves the pavement's susceptibility to low-temperature cracking, and absorb more stress at the crack tips than the conventional asphalt pavement. Laboratory tests were conducted to evaluate the tension/compression performance of a blend of asphalt rubber with rubber aggregate (ARRA). An optimum design methodology was introduced by examining the effect of asphalt source, curing temperature, curing time, rubber content, aggregate size, compaction pressure, and the effect of certain additives. At ambient temperature, the ARRA with equal amount of binder and aggregate exhibits good mechanical properties. Vestenamer helps improve the pavement's strength, stiffness, and fracture resistance to low temperature cracking. It was demonstrated that such pavement meets the mechanical requirements for recreational trails, such as bicycle, or pedestrian trails. ARRA is a viscoelastic material which exhibits time-dependent and loading rate-dependent behavior. Temperature is a key issue to its response to an external load. Both temperature and rate dependences were investigated. A series of uniaxial compression relaxation tests on ARRA or Vestenamer modified ARRA were conducted at room temperature to study the time-dependent performance of ARRA. Schapery's theory was applied to characterize the nonlinear viscoelastic behavior of ARRA.

  14. Theory of powdery rubber wear

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2009-12-01

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear.

  15. Modeling mechanical properties of core-shell rubber-modified epoxies

    SciTech Connect

    Wang, X.; Xiao, K.; Ye, L.; Mai, Y.W.; Wang, C.H.; Rose, L.R.F.

    2000-01-24

    Experiments have been carried out to quantify the effects of rubber content and strain rate on the elastic and plastic deformation behavior of core-shell rubber-modified epoxies. Both the Young's modulus and the yield stress were found to be slightly dependent on strain rate, but very sensitive to the volume fraction of rubber particles. Finite element analyses have also been performed to determine the influences of rubber content on the bulk elasticity modulus and the yield stress. By comparing with experimental results, it is found that the Young's modulus of rubber-toughened epoxies can be accurately estimated using the Mori-Tanaka method, provided that the volume fraction of rubber particles is appropriately evaluated. A yield function is provided that the volume fraction of rubber particles is appropriately evaluated. A yield function is proposed to quantify the effects of hydrostatic stress on the plastic yielding behaviors of rubber-modified epoxies. Agreement with experimental results is good. Also, a visco-plastic model is developed to simulate the strain-rate-dependent stress-strain relations.

  16. Biodesulfurization of rubber materials

    SciTech Connect

    Torma, A.E. ); Raghavan, D. . Dept. of Materials Science and Engineering)

    1990-01-01

    One of the most challenging problems in municipal waste treatment is the recycling of polymeric waste materials. The present study has demonstrated the applicability of biotechnological principles in the desulfurization of rubber using shake flask and Warburg respirometric techniques. In terms of oxygen uptake and specific rate of oxygen uptake, it was found that the mixed culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans was more efficient in this process than the individual pure cultures of these bacteria. Furthermore, the mixed cultures resulted in ten times higher sulfur removals from rubber relative to those of sterile controls. Additional studies are needed to elucidate the mechanisms of biodesulfurization of rubber. It is expected that the development of this process may provide a solution to recycling of car tire materials. 32 refs., 4 figs., 3 tabs.

  17. Smart damper using the combination of magnetic friction and pre-compressed rubber springs

    NASA Astrophysics Data System (ADS)

    Choi, Eunsoo; Choi, Gyuchan; Kim, Hong-Taek; Youn, Heejung

    2015-09-01

    This paper proposes a new concept of a smart damper using the combination of magnetic friction and rubber springs. The magnet provides energy dissipation, and the rubber springs with precompression contribute to increasing the recentering capacity of the damper. To verify their performance, dynamic tests of magnet frictional dampers and precompressed rubber springs were conducted. For this purpose, hexahedron neodymium (NdFeB) magnets and polyurethane rubber cylinders were used. In the dynamic tests, the loading frequency was varied from 0.1 to 2.0 Hz. The magnets showed almost perfect rectangular behavior in the force-deformation curve, and the frictional coefficient of the magnets was estimated through averaging and regression. The rubber springs were tested with and without precompression. The rubber springs showed different loading path from the second cycle and residual deformation that was not recovered immediately. The rubber springs showed greater rigid force with increasing precompression. Finally, this paper discusses the combination of rigid-elastic behavior and friction to generate 'flag-shaped' behavior for a smart damper and suggests how to combine magnets and rubber springs to obtain flag-shaped behavior. The performance of the magnets and precompressed rubber springs was verified through analytical models.

  18. Recycled rubber in cement composites

    SciTech Connect

    Raghavan, D.; Tratt, K.; Wool, R.P.

    1994-12-31

    Disposal of 200 million waste tires in the US each year has become a major problem. An environmentally sound innovative technology of recycling rubber in cement matrix was examined. Using silane coupling agent the rubber was bonded to the hydrating cement making a lighter composite, which absorbed more energy than ordinary Portland cement. The bonding information was obtained by peel strength analysis. SEM was used to understand the mode of fracture in pure cement paste, cement bonded rubber composite and rubber filled cement paste. It was found that cracks propagate through the rubber particle in rubber bonded cement composite while in unbonded rubber cement mix, the cracks propagate around the interface. The density and shrinkage measurements are also discussed.

  19. Recycling rubber products sensibly

    SciTech Connect

    Fesus, E.M.; Eggleton, R.W.

    1991-03-01

    This article examines processes for surface treating ground rubber from tires and other sources to enhance its ability to chemically bond with an uncured elastomer matrix during vulcanization. The topics discussed are environmental effects, processing and physical and chemical properties, mesh size, compounding, loading study, mineral fillers, and applications.

  20. Rubber cement poisoning

    MedlinePlus

    ... common household glue. It is often used for arts and crafts projects. Breathing in large amounts of rubber cement fumes or swallowing any amount can be extremely dangerous, especially for a small child. This article is for information only. Do NOT ...

  1. Measurement of Silicone Rubber Using Impedance Change of a Quartz-Crystal Tuning-Fork Tactile Sensor

    NASA Astrophysics Data System (ADS)

    Itoh, Hideaki; Yamada, Yuuki

    2006-05-01

    Silicone rubber has been investigated experimentally using the impedance change (Δ R) of a quartz-crystal tuning-fork tactile sensor when its base is in contact with the surface of many kinds of rectangular silicone rubber plates in order to discover how viscosity and elasticity of silicone rubber may be separately determined. Eleven silicone rubber plates (the values of the rubber hardness are JIS85, 80, 70, 65, 60, 50, 45, 40, 35, 30, and 20) are investigated in this experiment. Δ R increases linearly according to acoustic impedance ρ C (ρ: density of silicone rubber, C: sound velocity of a longitudinal acoustic wave in silicone rubber). We compare Δ R with ρ C when C is calculated in three cases: in first, C is calculated using Young’s modulus of silicone rubber measured by a tensiometer; in second, using Young’s modulus which is converted by the shear modulus measured by a rotating viscometer using the Poisson ratio of silicone rubber, 0.49; in third, using a complex Young’s modulus which is converted by the complex shear modulus measured by a rotating viscometer. We investigated which case in the three described showed good linearity between Δ R and ρ C. In order to clarify how the longitudinal plane wave generated in the sensor’s base travels into the silicone rubber plate, Δ R is measured when the tactile sensor is in contact with the surface of the rectangular silicone rubber plates of varying thickness and a size.

  2. Nonlinear Viscoelastic Mechanics of Cross-linked Rubbers

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.; Leonov, Arkady I.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    The paper develops a general theory for finite rubber viscoelasticity, and specifies it in the form, convenient for solving problems important for rubber, tire and space industries. Based on the quasi-linear approach of non-equilibrium thermodynamics, a general nonlinear theory has been developed for arbitrary nonisothermal deformations of viscoelastic solids. In this theory, the constitutive equations are presented as the sum of known equilibrium (rubber elastic) and non-equilibrium (liquid polymer viscoelastic) terms. These equations are then simplified using several modeling arguments. Stability constraints for the proposed constitutive equations are also discussed. It is shown that only strong ellipticity criteria are applicable for assessing stability of the equations governing viscoelastic solids.

  3. Study on the Aging Behaviors of Rubber Materials in Tension and Compression Loads

    NASA Astrophysics Data System (ADS)

    Jiang, Can; Wang, Hongyu; Ma, Xiaobing

    Rubber materials are widely used in aviation, aerospace, shipbuilding, automobile and other military field. However, rubber materials are easy to aging, which largely restricts its using life. In working environment, due to the combined effect of heat and oxygen, vulcanized rubber will undergo degradation and crosslinking reaction which will cause elasticity decease and permanent deformation, so mostly rubber products are used under stress state. Due to the asymmetric structure and asymmetric stress distribution, mechanical stress may cause serious damage to molecular structure; therefore, this paper is aimed to analyze the aging behavior of rubber materials under tensile and compressive loadings, through analyzing experiment data, and adopting Gauss function to describe stress relaxation coefficient, to build an aging equation containing compression ratio parameter and aging time.

  4. Adaptive robust control of a class of non-affine variable-speed variable-pitch wind turbines with unmodeled dynamics.

    PubMed

    Bagheri, Pedram; Sun, Qiao

    2016-07-01

    In this paper, a novel synthesis of Nussbaum-type functions, and an adaptive radial-basis function neural network is proposed to design controllers for variable-speed, variable-pitch wind turbines. Dynamic equations of the wind turbine are highly nonlinear, uncertain, and affected by unknown disturbance sources. Furthermore, the dynamic equations are non-affine with respect to the pitch angle, which is a control input. To address these problems, a Nussbaum-type function, along with a dynamic control law are adopted to resolve the non-affine nature of the equations. Moreover, an adaptive radial-basis function neural network is designed to approximate non-parametric uncertainties. Further, the closed-loop system is made robust to unknown disturbance sources, where no prior knowledge of disturbance bound is assumed in advance. Finally, the Lyapunov stability analysis is conducted to show the stability of the entire closed-loop system. In order to verify analytical results, a simulation is presented and the results are compared to both a PI and an existing adaptive controllers. PMID:27157849

  5. Dynamic Spring Model of Rubber Bush Based on Linear Viscoelasticity

    NASA Astrophysics Data System (ADS)

    Fujikawa, Masaki; Sato, Masami; Kobayashi, Takaya

    A set of simplified formulae is proposed for estimating the dynamic spring constants of rubber bushes used in suspension systems. These formulae are structured by extending a set of elastic solutions[Editor2] proposed before to calculate the dynamic spring constants according to the associated law (pseudo-elasticity) of the linear viscoelasticity theory. A unique feature of this method is that it helps in the easy and quick evaluation of the dynamic behavior of rubber bushes for all the six degrees of freedom (axial loading, loading normal to an axis in two directions, wrench in two directions, and torsion[Editor3]) with no direct involvement of the FEM. In order to validate this method of calculation, the results obtained for all the degrees of freedom are compared with those obtained using the FEM. It is verified that this approach is capable of qualitatively reproducing the results obtained by using the FEM analysis.

  6. Crumb rubber feasibility report

    SciTech Connect

    1985-11-01

    The Cumberland County supply region generates approximately 58,000 tons of scrap tires each year, equivalent to 45,000 tons of rubber after processing. Approximately 8,000 tons per year are in concentrated locations and can be easily collected. The costs of collection for the remainder vary significantly. Given current markets, economically feasible processes (ambient technology) can reprocess approximately 65 to 75 percent of the 37,000 tons into a marketable product. A processing plant sized for this supply would process 120 tons per day, a viable plant by industry standards. The end uses for whole tires constitute a negligible market, aside from the retreader market. Crumbed rubber is the major development efforts, there are potentially large opportunities in North Carolina.

  7. Theory of powdery rubber wear.

    PubMed

    Persson, B N J

    2009-12-01

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear. PMID:21832508

  8. A numerical investigation on mechanical property improvement of styrene butadine rubber by static straight blade indentation

    NASA Astrophysics Data System (ADS)

    Setiyana, B.; Ismail, R.; Jamari, J.; Schipper, D. J.

    2016-04-01

    Mechanical property improvement of rubber is widely carried out by adding carbon black or silica as a filler in rubber. In general, this improvement aims on the increase of stiffness and abrasion resistance. By means of the static straight blade indentation technique, this paper studies the mechanical properties of Unfilled Styrene Butadiene Rubber (SBR-0) and Filled Styrene Butadiene Rubber that is compounded with carbon black (SBR-25). The numerical method applied was Finite Element Analysis (FEA) in which the rubber was modeled as a hyper-elastic material and indented by a blade indenter with various wedge angles i.e. 30, 45 and 60 degrees. At the same depth of indentation, the results showed that there was an increase in both rubber stiffness and maximum stress if the rubber was compounded. However, it is found that the rubber stiffness showed a regular slight increase, while the maximum stress experienced an irregularly significant increase. Especially for the 30 degree wedge angle, the maximum stress extremely increased at a certain depth of indentation.

  9. Foundation, analysis, and numerical investigation of a variational network-based model for rubber

    NASA Astrophysics Data System (ADS)

    Gloria, Antoine; Le Tallec, Patrick; Vidrascu, Marina

    2014-01-01

    Since the pioneering work by Treloar, many models based on polymer chain statistics have been proposed to describe rubber elasticity. Recently, Alicandro, Cicalese, and the first author rigorously derived a continuum theory of rubber elasticity from a discrete model by variational convergence. The aim of this paper is twofold. First, we further physically motivate this model and complete the analysis by numerical simulations. Second, in order to compare this model to the literature, we present in a common language two other representative types of models, specify their underlying assumptions, check their mathematical properties, and compare them to Treloar's experiments.

  10. Oscillatory instability in slow crack propagation in rubber under large deformation.

    PubMed

    Endo, Daiki; Sato, Katsuhiko; Hayakawa, Yoshinori

    2012-07-01

    We performed experiments to investigate slow fracture in thin rubber films under uniaxial tension using high-viscosity oils. In this system we observed an oscillating instability in slowly propagating cracks for small applied strains. The transition between oscillatory and straight patterns occurred near the characteristic strain at which rubber exhibits a nonlinear stress-strain relation. This suggests that nonlinear elasticity plays an important role in the formation of the observed pattern. This was confirmed by numerical simulation for neo-Hookean and linear elasticity models. PMID:23005490

  11. Oscillatory instability in slow crack propagation in rubber under large deformation

    NASA Astrophysics Data System (ADS)

    Endo, Daiki; Sato, Katsuhiko; Hayakawa, Yoshinori

    2012-07-01

    We performed experiments to investigate slow fracture in thin rubber films under uniaxial tension using high-viscosity oils. In this system we observed an oscillating instability in slowly propagating cracks for small applied strains. The transition between oscillatory and straight patterns occurred near the characteristic strain at which rubber exhibits a nonlinear stress-strain relation. This suggests that nonlinear elasticity plays an important role in the formation of the observed pattern. This was confirmed by numerical simulation for neo-Hookean and linear elasticity models.

  12. Rubber composition compatible with hydrazine

    NASA Technical Reports Server (NTRS)

    Repar, J.

    1973-01-01

    Formulation improves compatibility of butyl rubbers with hydrazine while reducing permeation to low levels necessary for prolonged storage in space. This is accomplished by replacing carbon-black filler with inert materials such as hydrated silica or clay. Pressure increases suggest that hydrazine is decomposed only slightly by new type of rubber.

  13. Natural Rubber from Domestic Crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The United States is wholly dependent upon imports of natural rubber from tropical countries and is the world’s largest consumer of this strategic raw material. Development of domestic rubber crops will create supply security for this strategic raw material, enhance rural development, and create bio...

  14. Recycled rubber roads

    SciTech Connect

    Not Available

    1989-02-01

    The paper describes several innovative approaches for recycling old tires in the construction of roads. In one, 18 inches of shredded tire chips (2 X 2 inches) were used on top of 6-8 inches of small stone to construct a road across a sanitary landfill. No compacting or linders were needed. In another application, sidewall mats linked together with steel strapping were used as a sub-base for a road across a swampy area. A third application uses 1/2 inch bits of groundup rubber tires as a replacement for aggregate in an asphalt road base.

  15. Robotically enhanced rubber hand illusion.

    PubMed

    Arata, Jumpei; Hattori, Masashi; Ichikawa, Shohei; Sakaguchi, Masamichi

    2014-01-01

    The rubber hand illusion is a well-known multisensory illusion. In brief, watching a rubber hand being stroked by a paintbrush while one's own unseen hand is synchronously stroked causes the rubber hand to be attributed to one's own body and to "feel like it's my hand." The rubber hand illusion is thought to be triggered by the synchronized tactile stimulation of both the subject's hand and the fake hand. To extend the conventional rubber hand illusion, we introduce robotic technology in the form of a master-slave telemanipulator. The developed one degree-of-freedom master-slave system consists of an exoskeleton master equipped with an optical encoder that is worn on the subject's index finger and a motor-actuated index finger on the rubber hand, which allows the subject to perform unilateral telemanipulation. The moving rubber hand illusion has been studied by several researchers in the past with mechanically connected rigs between the subject's body and the fake limb. The robotic instruments let us investigate the moving rubber hand illusion with less constraints, thus behaving closer to the classic rubber hand illusion. In addition, the temporal delay between the body and the fake limb can be precisely manipulated. The experimental results revealed that the robotic instruments significantly enhance the rubber hand illusion. The time delay is significantly correlated with the effect of the multisensory illusion, and the effect significantly decreased at time delays over 100 ms. These findings can potentially contribute to the investigations of neural mechanisms in the field of neuroscience and of master-slave systems in the field of robotics. PMID:25532152

  16. A micro-continuum-mechanical material model for failure of rubber-like materials: Application to ageing-induced fracturing

    NASA Astrophysics Data System (ADS)

    Dal, Hüsnü; Kaliske, Michael

    2009-08-01

    Rubbery polymers are subjected to severe environmental conditions under service. As a consequence of various ageing mechanisms, the outer surface of rubber components hardens in time and cracking occurs as a result of combined mechanical and chemical processes. Conventional phenomenological hyperelastic constitutive models do not account for material softening. Consequently, the stored energy and stresses tend to infinity as stretch increases. In this contribution, a network alteration for the ageing mechanism of rubber-like materials is introduced along with a micromolecular description of material failure. The proposed micro-continuum material model is based on a serial construction of a Langevin-type spring representing the energy storage owing to conformational changes induced by deformation, to a bond potential representing the energy stored in the polymer chain due to the interatomic displacement. For the representation of the micro-macro transition, the non-affine kinematics of the micro-sphere model is used. The Morse potential is utilized for the interatomic bond, which describes the energetic contribution to rubber-like materials and governs the failure of the polymer chain in terms of bond rupture. A novel numerical scheme for the FE implementation of the proposed model is demonstrated. The hardening phenomenon as a result of diffusion limited oxidation of rubber is explained by the principle of mass conservation which dictates simultaneous modulus hardening along with decrease in ultimate stretch observed in aged rubbery polymers.

  17. Energy functions for rubber from microscopic potentials

    NASA Astrophysics Data System (ADS)

    Johal, A. S.; Dunstan, D. J.

    2007-04-01

    The finite deformation theory of rubber and related materials is based on energy functions that describe the macroscopic response of these materials under deformation. Energy functions and elastic constants are here derived from a simple microscopic (ball-and-spring) model. Exact uniaxial force-extension relationships are given for Hooke's Law and for the thermodynamic entropy-based microscopic model using the Gaussian and the inverse Langevin statistical approximations. Methods are given for finding the energy functions as expansions of tensor invariants of deformation, with exact solutions for functions that can be expressed as expansions in even powers of the extension. Comparison with experiment shows good agreement with the neo-Hookean energy function and we show how this derives directly from the simple Gaussian statistical model with a small modification.

  18. Chlorinolysis reclaims rubber of waste tires

    NASA Technical Reports Server (NTRS)

    Dufresne, E. R.; Tervet, J. H.; Hull, G. G.

    1981-01-01

    Process reclaims rubber and reduces sulfur content by using chlorine gas to oxidize sulfur bonds in preference to other bonds. Rubber does not have poor hysteresis and abrasion resistance like conventionally reclaimed rubber and is suitable for premium radial tires. Chlorinated rubber is less susceptible to swelling by oils and may be used as paint ingredient.

  19. Recycling, production and use of reprocessed rubbers

    SciTech Connect

    Klingensmith, B. )

    1991-03-01

    This article examines the various methods used to produce recycled rubber and to compare their characteristics and application. The topics discussed include reclaiming by chemical digestion, devulcanization by the severing of sulfur bonds, ambient temperature and cryogenically ground rubber, processing and mixing of ground rubber, and properties of reclaimed rubbers by reclamation method.

  20. Investigating Low Temperature Properties of Rubber Seals - 13020

    SciTech Connect

    Jaunich, M.; Wolff, D.; Stark, W.

    2013-07-01

    To achieve the required tightness levels of containers for low and intermediate level radioactive wastes rubbers are widely applied as main sealing materials. The save encapsulation of the radioactive container contents has to be guaranteed according to legislation and appropriate guidelines for long storage periods as well as down to temperatures of -40 deg. C during transportation. Therefore the understanding of failure mechanisms that lead to leakage at low temperatures is of high importance. It is known that the material properties of rubbers are strongly influenced by temperature. At low temperatures this is caused by the rubber-glass transition (abbr. glass transition). During continuous cooling the material changes from rubber-like entropy-elastic to stiff energy-elastic behaviour, that allows nearly no strain or retraction. Therefore, rubbers are normally used above their glass transition but the minimum working temperature limit is not defined precisely, what can cause problems during application. The temperature range where full functionality is possible is strongly dependent on the application conditions and the material. For this investigation mainly ethylene propylene diene (EPDM) and fluorocarbon rubbers (FKM) were selected as they are often used for radioactive waste containers. Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) are typically used for the determination of the temperature range of the glass transition process. The standardized compression set measurement according to ISO 815 is common for investigation of rubber sealing materials as the test simulates the seal behaviour after release. To reduce the test time of the standard tests a faster technique giving the same information was developed. Additionally, the breakdown temperature of the sealing function of complete O-ring seals is measured in a component test setup to compare it with the results of the other tests. The experimental setup is capable of

  1. Vibration isolation of beam structure using hybrid mount associated with rubber and piezoactuator

    NASA Astrophysics Data System (ADS)

    Choi, Seung-Bok; Kim, Seung-Hwan; Hong, Sung-Ryong

    2003-08-01

    A hybrid mount featuring elastic rubber and piezoelectric material is proposed and applied to the vibration control of a beam structure subjected to high frequency excitations. A mechanical model of the proposed hybrid mount is derived, and then the frequency-dependent dynamic stiffness of rubber and the voltage-dependent stroke of piezoactuator are verified experimentally. After formulating a mathematical model of the beam structure associated with the hybrid mount and the passive rubber mounts, a robust sliding mode controller is designed to attenuate vibration of the beam structure. The controller is experimentally realized and control responses such as accelerations of the beam structure and force transmission through the hybrid mount and rubber mounts are presented in frequency domain.

  2. In vitro biocompatibility of EPM and EPDM rubbers.

    PubMed

    Mast, F; Hoschtitzky, J A; Van Blitterswijk, C A; Huysmans, H A

    1997-01-01

    The in vitro toxicity of two EPDM rubbers (K 778 and K 4802) and one EPM rubber (K 740) was tested using human fibroblasts. The modulus of elasticity of each rubber was varied by exposure to different amounts of electron-beam radiation (0, 5 and 10 Mrad). The short-term in vitro toxicity was tested by culturing cells on polymer films. The long-term effect of ageing was simulated by growing fibroblasts in nutrient media prepared from extracts of heat-exposed materials. Cell cultures were studied both quantitatively and (ultra) structurally. Growth curves obtained in the toxicity test did not differ significantly from control values at any day of observation, and also showed that electron-beam radiation did not alter the biocompatibility. The same results were found for all but one material in the artificial ageing test. The number of cells in the K4802/10 Mrad extraction medium was decreased. Ultrastructurally no gross deviations from normal morphology were observed, either in the direct contact test or in the artificial ageing test. The most characteristic feature was a somewhat dilated endoplasmic reticulum. In summary, the in vitro biocompatibility of EPDM-rubbers as observed in this study is satisfactory and motivates further investigation of their biocompatibility in animal experiments. PMID:15348835

  3. Characterization of Hexsyn, a polyolefin rubber.

    PubMed

    McMillin, C R

    1987-07-01

    Hexsyn is the Goodyear Tire and Rubber Company tradename for a polyolefin rubber synthesized from 1-hexene with 3-5% methylhexadiene as the source of residual double bonds for vulcanization. Under license from Goodyear, this same polymer has been manufactured by Lord Corporation for the hinge portion of finger joint prostheses using the tradename Bion. This rubber is currently licensed to the University of Akron and to the Cleveland Clinic Foundation for use in biomedical applications, and is being used primarily for biocompatible and highly fatigue resistant rubber components in ventricular assist and artificial heart systems. Results are presented from the physical, mechanical, and biological characterization of Hexsyn. Procedures are described for the synthesis, compounding, and post-molding extraction for Hexsyn. The physical testing of Hexsyn reported includes determinations of its density at 23 and 37 degrees C, initial hardness and hardness after aging in oxygen, blood, pseudoextracellular fluid and polyethylene glycol 600, typical molecular weights determined by gel permeation chromatography/low angle laser light scattering and intrinsic viscosity, thermal analyses by differential scanning calorimetry of Hexsyn gum, and vulcanized Hexsyn after exposure to blood and blood/fatigue conditions. Also reported are results of differential thermal analyses, thermomechanical analyses of virgin and annealed samples, and thermogravimetric analyses conducted in helium and in air. Dynamic mechanical analyses of Hexsyn include Clash-Berg and Rheovibron tests. Swelling was conducted to determine lot-to-lot and sheet-to-sheet variation for quality control and also a number of solvents were used so that the polymer-solvent interaction parameters could be determined. The permeability of Hexsyn to water, water vapor, and a variety of gases is reported. The permeability by contact angle measurements, refractive index, residual solvent analyses, migration of blood components

  4. Stress-Strain Relation and strain-Induced Crystallization in Rubber

    SciTech Connect

    Toki,S.

    2006-01-01

    Rubber is composed of flexible chains and network points. Theory of rubber elasticity succeeds to elucidate stress-strain relation of rubber using the inverse Langevin equation of entropy modulus. However, actual rubber is much different from ideal networks composed of ideal rubber chains. Network points may not distribute homogeneously and the molecular weight between two network points may show wide distribution. Flexible chains show strain-induced crystallization. Recent synchrotron X-ray and simultaneous stress-strain measurements reveal that strain-induced crystallization reduces the stress by increasing the length of molecules along the stretching direction. Also, strain-induced crystals are created not at the middle of the network points, but at the close location to the network points. The hybrid structure of strain-induced crystallites and network points may be stronger than network points alone. Therefore, strain induced crystallization may increase the tensile strength of rubber by two mechanisms, they are, increase of elongation at break and reinforcement of network points. Natural rubber has biotic network points in nature. After vulcanization, the biotic network may contribute the superior toughness of NR, comparing to IR. Carbon filled NR also shows strain induced crystallization. In order to acquire high tensile strength, molecules should have higher flexibility to perform strain induced crystallization by selecting a kind of carbon blacks, an accelerator and a curing condition.

  5. Rubber stopper remover

    DOEpatents

    Stitt, Robert R.

    1994-01-01

    A device for removing a rubber stopper from a test tube is mountable to an upright wall, has a generally horizontal splash guard, and a lower plate spaced parallel to and below the splash guard. A slot in the lower plate has spaced-apart opposing edges that converge towards each other from the plate outer edge to a narrowed portion, the opposing edges shaped to make engagement between the bottom of the stopper flange and the top edge of the test tube to wedge therebetween and to grasp the stopper in the slot narrowed portion to hold the stopper as the test tube is manipulated downwardly and pulled from the stopper. The opposing edges extend inwardly to adjoin an opening having a diameter significantly larger than that of the stopper flange.

  6. Identification of a Taraxacum brevicorniculatum rubber elongation factor protein that is localized on rubber particles and promotes rubber biosynthesis.

    PubMed

    Laibach, Natalie; Hillebrand, Andrea; Twyman, Richard M; Prüfer, Dirk; Schulze Gronover, Christian

    2015-05-01

    Two protein families required for rubber biosynthesis in Taraxacum brevicorniculatum have recently been characterized, namely the cis-prenyltransferases (TbCPTs) and the small rubber particle proteins (TbSRPPs). The latter were shown to be the most abundant proteins on rubber particles, where rubber biosynthesis takes place. Here we identified a protein designated T. brevicorniculatum rubber elongation factor (TbREF) by using mass spectrometry to analyze rubber particle proteins. TbREF is homologous to the TbSRPPs but has a molecular mass that is atypical for the family. The promoter was shown to be active in laticifers, and the protein itself was localized on the rubber particle surface. In TbREF-silenced plants generated by RNA interference, the rubber content was significantly reduced, correlating with lower TbCPT protein levels and less TbCPT activity in the latex. However, the molecular mass of the rubber was not affected by TbREF silencing. The colloidal stability of rubber particles isolated from TbREF-silenced plants was also unchanged. This was not surprising because TbREF depletion did not affect the abundance of TbSRPPs, which are required for rubber particle stability. Our findings suggest that TbREF is an important component of the rubber biosynthesis machinery in T. brevicorniculatum, and may play a role in rubber particle biogenesis and influence rubber production. PMID:25809497

  7. A study of the influence of micro and nano phase morphology on the mechanical properties of a rubber-modified epoxy resin

    NASA Astrophysics Data System (ADS)

    Russell, Bobby Glenn

    Epoxy resins are thermosets with extraordinary adhesion; high strength; good resistance to creep, heat, and chemicals; and they have low shrinkage. Conversely, these polymers are brittle, they are sensitive to moisture, and they exhibit poor toughness. To improve their toughness, they are often modified by introducing dispersed rubber particles in the primary phase. In this study, the epoxy resin was modified with carboxyl-terminated butadiene acrylonitrile (CTBN), liquid-reactive rubbers. The initiator concentration, percent acrylonitrile in the CTBN rubber, and cure temperatures were altered to give varying materials properties. Statistical analysis of the morphology data showed that the percentage of rubber acrylonitrile had an effect on both the rubber particle size and volume fraction. The cure temperature had an effect on the rubber particle volume and modulus. Plots of the rubber particle size, volume fraction, and modulus versus bulk elastic storage modulus and fracture toughness revealed that rubber particle size had no effect on bulk properties, volume fraction and rubber particle modulus had an effect on both the bulk storage elastic modulus and fracture toughness.

  8. A Micro-Mechanically Based Continuum Model for Strain-Induced Crystallization in Natural Rubber

    NASA Astrophysics Data System (ADS)

    Mistry, Sunny Jigger

    Recent experimental results show that strain-induced crystallization can substantially improve the crack growth resistance of natural rubber. While this might suggest superior designs of tires or other industrial applications where elastomers are used, a more thorough understanding of the underlying physics of strain-induced crystallization in natural rubber has to be developed before any design process can be started. The objective of this work is to develop a computationally-accessible micro-mechanically based continuum model, which is able to predict the macroscopic behavior of strain crystallizing natural rubber. While several researchers have developed micro-mechanical models of partially crystallized polymer chains, their results mainly give qualitative agreement with experimental data due to a lack of good micro-macro transition theories or the lack of computational power. However, recent developments in multiscale modeling in polymers provide new tools to continue this early work. In this thesis, a new model is proposed to model strain-induced crystallization in natural rubber. To this end, a micro-mechanical model of a constrained partially crystallized polymer chain with an extended-chain crystal is derived and connected to the macroscopic level using the non-affine micro-sphere model. On the macroscopic level, a thermodynamically consistent framework for strain-crystallizing materials is developed, and a description of the crystallization kinetics is introduced. For that matter, an evolution law for crystallization based on the gradient of the macroscopic Helmholtz free energy function (chemical potential) in combination with a simple threshold function is used. A numerical implementation of the model is proposed and its predictive performance assessed using published data.

  9. Silicone-Rubber Stitching Seal

    NASA Technical Reports Server (NTRS)

    Wang, D. S.

    1985-01-01

    Fabric products protected from raveling by coating threads and filling stitching holes with silicone rubber. Uncored silicone rubber applied to stitching lines with air-pressurized sealant gun. Next, plastic release film placed on coated side, and blanket flipped over so release film lies underneath. Blanket then bagged and adhesive cured under partial vacuum of about 3.5 psi or under pressure. Applications include balloons, parachutes, ultralight aircraft, sails, rescue harnesses, tents, or other fabric products highly stressed in use.

  10. Wear of steel by rubber

    NASA Technical Reports Server (NTRS)

    Gent, A. N.; Pulford, C. T. R.

    1978-01-01

    Wear of a steel blade used as a scraper to abrade rubber surfaces has been found to take place much more rapidly on a cis-polyisoprene (natural rubber) surface than on a cis-polybutadiene surface, and much more rapidly in an inert atmosphere than in air. These observations are attributed to the direct attack upon steel of free-radical species generated by mechanical rupture of elastomer molecules during abrasion.

  11. Rubber shock absorber for deep-well rod operated pumps

    SciTech Connect

    Bagirov, M.M.

    1984-05-01

    Tests of hydropneumatic shock absorbers of deep-well pumps in oil fields showed that they improve the efficiency of the installations by their design is very complicated. Mechanically acting absorbers of dynamic forces are simpler in design. Rubber shock absorbers differ advantageously from spring absorbers in that considerable oscillation-damping forces of any amplitude act in them. The design of a shock absorber is described which is situated under the balance arm of a pumping jack. A prototype of the shock absorber, in which the elastic elements were cylinders made of rubber was tested in a test borehole. Dynamographic recordings made in this borehole in operation with and without shock absorber show that the shock absorber reduces the maximum load on the rods and the double amplitude of load change. Calculations show that when the described shock absorber is used the reduced load is 11-18% smaller. This may considerably reduce the number of breakages of deepwell pump rods.

  12. A three-level non-deterministic modeling methodology for the NVH behavior of rubber connections

    NASA Astrophysics Data System (ADS)

    Stenti, A.; Moens, D.; Sas, P.; Desmet, W.

    2010-03-01

    Complex built-up structures such as vehicles have a variety of joint types, such as spot-welds, bolted joints, rubber joints, etc. Rubber joints highly contribute to the nonlinear level of the structure and are a major source of uncertainties and variability. In the general framework of developing engineering tools for virtual prototyping and product refinement, the modeling of the NVH behavior of rubber joints involve the computational burden of including a detailed nonlinear model of the joint and the uncertainties and variability typical of that joint in a full-scale system model. However, in an engineering design phase the knowledge on the joint rubber material properties is typically poor, and the working conditions a rubber joint will experience are generally not known in detail. This lack of knowledge often do not justify the computational burden and the modeling effort of including detailed nonlinear models of the joint in a full-scale system model. Driven by these issues a non-deterministic numerical methodology based on a three-level modeling approach is being developed. The methodology aims at evaluating directly in the frequency domain the sensitivity of the NVH behavior of a full-scale system model to the rubber joint material properties when nonlinear visco-elastic rubber material behavior is considered. Rather than including directly in the model a representation of the rubber nonlinear visco-elastic behavior, the methodology proposes to model the material nonlinear visco-elastic behavior by using a linear visco-elastic material model defined in an interval sense, from which the scatter on the full-scale system NVH response is evaluated. Furthermore the development of a multi-level solution scheme allows to reduce the computational burden introduced by the non-deterministic approach by allowing the definition of an equivalent linear interval parametric rubber joint model, ready to be assembled in a full-scale system model at a reasonable

  13. Coprocessing of coal and waste rubber

    SciTech Connect

    Farcasiu, M.; Smith, C.M. )

    1992-01-01

    The disposal of used tires, the main source of waste rubber, is an important environmental problem. We describe a method to transform used rubber tires into useful liquid products by coprocessing them with coal. Carbon black, an important constituent in rubber tires, provides a good hydrocracking catalyst during coprocessing. Due to the presence of carbon black in the rubber tires, the yields of liquids obtained by coal-rubber tires coprocessing are superior to those that could be obtained by coprocessing rubber with coal in the absence of carbon black.

  14. Coprocessing of coal and waste rubber

    SciTech Connect

    Farcasiu, M.; Smith, C.M.

    1992-05-01

    The disposal of used tires, the main source of waste rubber, is an important environmental problem. We describe a method to transform used rubber tires into useful liquid products by coprocessing them with coal. Carbon black, an important constituent in rubber tires, provides a good hydrocracking catalyst during coprocessing. Due to the presence of carbon black in the rubber tires, the yields of liquids obtained by coal-rubber tires coprocessing are superior to those that could be obtained by coprocessing rubber with coal in the absence of carbon black.

  15. A polymeric flame retardant additive for rubbers

    SciTech Connect

    Ghosh, S.N.; Maiti, S.

    1993-12-31

    Synthesis of a polyphosphonate by the interfacial polymerization of bisphenol-A (BPA) and dichloro-phenyl phosphine oxide (DCPO) using cetyltrimethyl ammonium chloride (TMAC) as phase transfer catalyst (PTC) was reported. The polyphosphonate was characterized by elemental analysis, IR, TGA, DSC and 1H-NMR spectroscopy. The flame retardancy of the polymer was done by OI study. The polymer was used as a fire retardant additive to rubbers such as natural rubber (NR), styrene-butadiene rubber(SBR), nitrile rubber (NBR) and chloroprene rubber (CR). The efficiency of the fire retardant property of this additive was determined by LOI measurements of the various rubber samples.

  16. Experimental Investigation on Mechanical Property of Metal Rubber Used in Lunar Rover at High or Low Temperature

    NASA Astrophysics Data System (ADS)

    Tao, J.; Deng, Z.; Gao, H.; Wang, S.; Hu, M.; Meng, X.

    Metal rubber is a kind of elastic damping material for aerospace environment It can keep its capacity even in some extreme environment such as high temperature high pressure high vacuum ultra-low temperature and violent vibration where traditional rubber can t deal with so it can be used in space craft as vibration reduction filter element and sealing element On the prototype of a lunar rover developed by Harbin Institute of Technology metal rubber is firstly used for the vibration dampers in the rover wheels In this paper the experimental investigation on rigidity and damping characteristic of metal rubber is carried out at high temperature and ultra-low temperature that corresponds to lunar environment The quasi-statics property of the samples made of metal rubber is tested at desired temperatures by the universal tensile testing machine model Y-71 The low temperatures down to -175° were realized by liquid nitrogen and the high temperatures up to 130° were realized by flexible electrical heater band Based on the method of least squares some curves to curve fit the experimental data on rigidity of the metal rubber samples at simulated temperatures to lunar environment were given The damping ratios of metal rubber at ordinary temperatures have been mentioned in some documents But there are hardly any reports about them at simulated temperatures to lunar environment Because it is difficult to know directly the exact damping mechanism of the metal rubber the free attenuation method is feasible to test its damping

  17. Natural rubber latex allergy.

    PubMed

    Deval, Ravi; Ramesh, V; Prasad, G B K S; Jain, Arun Kumar

    2008-01-01

    Natural rubber latex (NRL) is a ubiquitous allergen as it is a component of > 40,000 products in everyday life. Latex allergy might be attributed to skin contact or inhalation of latex particles. Latex allergy is an IgE-mediated hypersensitivity to NRL, presenting a wide range of clinical symptoms such as angioedema, swelling, cough, asthma, and anaphylactic reactions. Until 1979, latex allergy appeared only as type IV delayed hypersensitivity; subsequently, the proportion of different allergy types drifted towards type IV contact allergy reactions. Several risk factors for sensitization to NRL are already known and well documented. Some authors have established a positive correlation between a history of multiple surgical interventions, atopy, spina bifida malformation, and latex allergy incidence. We suspect an increase in latex allergy incidence in association with increased atopy and sensitivity to environmental allergens in the industrial population. It is often postulated in literature that the groups of workers at risk for this allergy are essentially workers in the latex industry and healthcare professionals. In this population, direct internal and mucosal contact with NRL medical devices may be the route of sensitization as factors such as the number of procedures and use of NRL materials (catheters and tubes) were associated with increased risk of latex sensitization and allergy. PMID:18797048

  18. Rolling tires into rubber

    SciTech Connect

    Malloy, M.G.

    1997-06-01

    For Envirotire (Lillington, North Carolina), producing quality crumb rubber this summer is all in a night`s work. The tire recycling facility has operated in Lillington, which is about an hour south of Raleigh, North Carolina, for about a year and a half, since October 1995. In the summer, the plant runs at night to save money in electricity costs by operating during off-peak hours; in the winter, daytime hours also can be off-peak. In contrast to the cryogenic systems used elsewhere to recycle tires, Envirotire`s system works on mechanical principles. Before the tires are even shredded, a worker cuts the white-walls out of the tires manually, so the white does not contaminate the black end-product. A worker places the tires manually on a conveyor, which feed them up to an initial shredder that sections them quickly into pieces. While the tires are on the conveyor, dividing strips on the conveyor mark off a place for each tire. The system takes nine new tires per minute.

  19. Silicone-Rubber Microvalves Actuated by Paraffin

    NASA Technical Reports Server (NTRS)

    Svelha, Danielle; Feldman, Sabrina; Barsic, David

    2004-01-01

    Microvalves containing silicone-rubber seals actuated by heating and cooling of paraffin have been proposed for development as integral components of microfluidic systems. In comparison with other microvalves actuated by various means (electrostatic, electromagnetic, piezoelectric, pneumatic, and others), the proposed valves (1) would contain simpler structures that could be fabricated at lower cost and (2) could be actuated by simpler (and thus less expensive) control systems. Each valve according to the proposal would include a flow channel bounded on one side by a flat surface and on the other side by a curved surface defined by an arched-cross-section, elastic seal made of silicone rubber [polydimethylsilane (PDMS)]. The seal would be sized and shaped so that the elasticity of the PDMS would hold the channel open except when the seal was pressed down onto the flat surface to close the channel. The principle of actuation would exploit the fact that upon melting or freezing, the volume of a typical paraffin increases or decreases, respectively, by about 15 percent. In a valve according to the proposal, the seal face opposite that of the channel would be in contact with a piston-like plug of paraffin. In the case of a valve designed to be normally open at ambient temperature, one would use a paraffin having a melting temperature above ambient. The seal would be pushed against the flat surface to close the channel by heating the paraffin above its melting temperature. In the case of a valve designed to be normally closed at ambient temperature, one would use a paraffin having a melting temperature below ambient. The seal would be allowed to spring away from the flat surface to open the channel by cooling the paraffin below its melting temperature. The availability of paraffins that have melting temperatures from 70 to +80 C should make it possible to develop a variety of normally closed and normally open valves. The figure depicts examples of prototype normally

  20. System identification methods for metal rubber devices

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Lang, Z. Q.; Billings, S. A.; Tomlinson, G. R.; Rongong, J. A.

    2013-08-01

    Metal rubber (MR) devices, a new wire mesh material, have been extensively used in recent years due to several unique properties especially in adverse environments. Although many practical studies have been completed, the related theoretical research on metal rubber is still in its infancy. In this paper, a semi-constitutive dynamic model that involves nonlinear elastic stiffness, nonlinear viscous damping and bilinear hysteresis Coulomb damping is adopted to model MR devices. The model is first approximated by representing the bilinear hysteresis damping as Chebyshev polynomials of the first kind and then generalised by taking into account the effects of noises. A very efficient systematic procedure based on the orthogonal least squares (OLS) algorithm, the adjustable prediction error sum of squares (APRESS) criterion and the nonlinear model validity tests is proposed for model structure detection and parameter estimation of MR devices for the first time. The OLS algorithm provides a powerful tool to effectively select the significant model terms step by step, one at a time, by orthogonalising the associated terms and maximising the error reduction ratio, in a forward stepwise manner. The APRESS statistic regularises the OLS algorithm to facilitate the determination of the optimal number of model terms that should be included into the model. And whether the final identified dynamic model is adequate and acceptable is determined by the model validity tests. Because of the orthogonal property of the OLS algorithm, the selection of the dynamic model terms and noise model terms are totally decoupled and the approach also leads to a parsimonious model. Numerical ill-conditioning problems which can arise in the conventional least squares algorithm can be avoided as well. The methods of choosing the sampling interval for nonlinear systems are also incorporated into the approach. Finally by utilising the response of a cylindrical MR specimen, it is shown how the model

  1. Electrospinning of PVC with natural rubber

    NASA Astrophysics Data System (ADS)

    Othman, Muhammad Hariz; Mohamed, Mahathir; Abdullah, Ibrahim

    2013-11-01

    Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber's mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

  2. Electrospinning of PVC with natural rubber

    SciTech Connect

    Othman, Muhammad Hariz; Abdullah, Ibrahim; Mohamed, Mahathir

    2013-11-27

    Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber’s mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

  3. Advances in rubber/halloysite nanotubes nanocomposites.

    PubMed

    Jia, Zhixin; Guo, Baochun; Jia, Demin

    2014-02-01

    The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties. PMID:24749454

  4. Rubber-like electrically conductive polymeric materials with shape memory

    NASA Astrophysics Data System (ADS)

    Cui, H. P.; Song, C. L.; Huang, W. M.; Wang, C. C.; Zhao, Y.

    2013-05-01

    This paper presents a heating-responsive shape memory polymeric material, which is not only rubber-like at room temperature and above its shape recovery temperature, but also electrically conductive. This polymeric material is made of silicone, melting glue (MG), and carbon black (CB). The influence of volume fractions of MG and CB on the elasticity, electrical resistivity, and shape memory effect of the polymeric material is systematically investigated. The feasibility of Joule heating for shape recovery is experimentally demonstrated with an electric power of 31 V.

  5. Combined effects of microwaves, electron beams and polyfunctional monomers on rubber vulcanization.

    PubMed

    Manaila, Elena; Martin, Diana; Stelescu, Daniela Zuga; Craciun, Gabriela; Ighigeanu, Daniel; Matei, Constantin

    2009-01-01

    This paper presents comparative results obtained by conventional vulcanization with benzoyl peroxide (CV-BP), separate electron beam vulcanization (EB-V) and simultaneous electron beam and microwave vulcanization (EB+MW-V) applied to two kind of rubber samples: EVA (ethylene vinyl acetate) rubber-sample (EVA-sample) and EPDM (ethylene-propylene terpolymer) rubber-sample (EPDM-sample). The EVA-samples contain 61.54% EVA Elvax 260, 30.77% carbon black, 1.85% TAC (triallylcyanurate) polyfunctional monomer and 5.84% filler (zinc oxide, stearic acid, polyethylene glycol and antioxidant). The EPDM-samples contain 61.54% EPDM Nordel 4760, 30.77% carbon black, 1.85% TMPT (trimethylopropane trimethacrylate) polyfunctional monomer and 5.84% filler (zinc oxide, stearic acid, polyethylene glycol and antioxidant). The rubber samples designed for different vulcanization methods were obtained from raw rubber mixtures, as compressed sheets of 2 mm in the polyethylene foils to minimize oxidation. For EB and EB + MW treatments the sheets were cut in rectangular shape 0.15 x 0.15 m2. The physical properties of samples obtained by CV-BP EV-Vand EB + MW-V methods were evaluated by measuring the tearing strength, residual elongation, elongation at break, tensile strength, 300% modulus, 100% modulus, elasticity and hardness. The obtained results demonstrate an improvement of rubber several properties obtained by EB and EB + MW processing as compared to classical procedure using benzoyl peroxide. PMID:21384707

  6. Effect of crumb-rubber particle size on mechanical response of polyurethane foam composites

    NASA Astrophysics Data System (ADS)

    Sanjay, Omer Sheik

    The compression properties of foam are governed by by three factors: i) cell edge bending ii) compression of cell fluid iii) membrane stresses in the cell faces. The effect of reinforcement, granular form of scrap tire rubber on contribution of each of these effects along with the physical properties of polyurethane foam is investigated. It is seen that the addition of crumb-rubber hinders the formation of cell membranes during the foaming process. Four different sizes of particles were chosen to closely study the effect of particle size on the physical properties of the foam composite. There is a definite pattern seen in each of the physical property of the composite with change in the particle size. Addition of crumb-rubber decreases the compressive strength but in turn increases the elastic modulus of the composite. The rubber particles act as the sites for stress concentration and hence the inclusion of rubber particles induces the capability to transfer the axial load laterally along the surface of the foam. Also, the filler material induces porosity into the foam, which is seen in the SEM images, and hence the addition of rubber particles induces brittleness, which makes the foam composites extensively applicable for structural application in sandwich components. The lightweight composite therefore is a potential substitute to the heavier metal foams and honeycombs as a protective layer.

  7. Rubber friction and tire dynamics.

    PubMed

    Persson, B N J

    2011-01-12

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms. PMID:21406818

  8. Rubber friction and tire dynamics

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2011-01-01

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  9. Pressure sensitive conductive rubber blends

    SciTech Connect

    Hassan, H.H. ); Abdel-Bary, E.M. ); El-Mansy, M.K.; Khodair, H.A. )

    1989-12-01

    Butadiene-acrylonitrile rubber (NBR) was blended with polychloroprene (CR) according to standard techniques. The blend was mixed with different concentrations of ZnO. The vulcanized sample was subjected to electrical conductivity ({sigma}) measurements while different values of static pressure were applied on the sample. It was found that samples containing 7.5 phr ZnO showed a reasonable pressure sensitive increase of {sigma}. Furthermore, the {sigma} vs pressure relationship of rubber blend mixed with different concentrations of Fast Extrusion Furnace black (FEF) was investigated. It was found that rubber vulcanizate containing 40 phr FEF resulted in a negative value of the pressure coefficient of conductivity {approx equal} {minus} 4.5 KPa{sup {minus}1}.

  10. Reinforced rubber composition containing ground coal

    SciTech Connect

    Sperley, R.J.

    1984-10-16

    A reinforced rubber composition is provided comprising a mixture of (a) a sulfur vulcanizable rubber and (b) ground coal having an average mesh size of 25 or more and which produces an aqueous slurry with a pH of less than 7.0, and wherein a metallic reinforcing member is embedded in the rubber mixture of (a) and (b).

  11. Elasticity theory

    NASA Astrophysics Data System (ADS)

    Moraru, Gheorghe; Mursa, Condrat

    2006-12-01

    In this book we present the basic concepts of the theory of elasticity: stress and deformation states (plane and three-dimensional) and generalized Hooke's law. We present a number of problems which have applications in strength analysis. The book includes a synthesis of the theory of elasticity and modern methods of applied mathematics. This book is designed for students, post graduate students and specialists in strength analysis. the book contains a number of appendixes which includes: elements of matrix-calculation, concepts of tensorial calculation, the Fourier transform, the notion of improper integrals,singular and hypersingular integrals, generalized functions, the Dirac Delta function

  12. Elasticity reconstructive imaging by means of stimulated echo MRI.

    PubMed

    Chenevert, T L; Skovoroda, A R; O'Donnell, M; Emelianov, S Y

    1998-03-01

    A method is introduced to measure internal mechanical displacement and strain by means of MRI. Such measurements are needed to reconstruct an image of the elastic Young's modulus. A stimulated echo acquisition sequence with additional gradient pulses encodes internal displacements in response to an externally applied differential deformation. The sequence provides an accurate measure of static displacement by limiting the mechanical transitions to the mixing period of the simulated echo. Elasticity reconstruction involves definition of a region of interest having uniform Young's modulus along its boundary and subsequent solution of the discretized elasticity equilibrium equations. Data acquisition and reconstruction were performed on a urethane rubber phantom of known elastic properties and an ex vivo canine kidney phantom using <2% differential deformation. Regional elastic properties are well represented on Young's modulus images. The long-term objective of this work is to provide a means for remote palpation and elasticity quantitation in deep tissues otherwise inaccessible to manual palpation. PMID:9498605

  13. Quantitative rubber sheet models of gravitation wells using Spandex

    NASA Astrophysics Data System (ADS)

    White, Gary

    2008-04-01

    Long a staple of introductory treatments of general relativity, the rubber sheet model exhibits Wheeler's concise summary---``Matter tells space-time how to curve and space-time tells matter how to move''---very nicely. But what of the quantitative aspects of the rubber sheet model: how far can the analogy be pushed? We show^1 that when a mass M is suspended from the center of an otherwise unstretched elastic sheet affixed to a circular boundary it exhibits a distortion far from the center given by h = A*(M*r^2)^1/3 . Here, as might be expected, h and r are the vertical and axial distances from the center, but this result is not the expected logarithmic form of 2-D solutions to LaPlace's equation (the stretched drumhead). This surprise has a natural explanation and is confirmed experimentally with Spandex as the medium, and its consequences for general rubber sheet models are pursued. ^1``The shape of `the Spandex' and orbits upon its surface'', American Journal of Physics, 70, 48-52 (2002), G. D. White and M. Walker. See also the comment by Don S. Lemons and T. C. Lipscombe, also in AJP, 70, 1056-1058 (2002).

  14. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    Bauman, Bernard D.; Williams, Mark A.; Bagheri, Reza

    1997-12-02

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  15. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, E.L.; Bauman, B.D.; Williams, M.A.

    1996-04-09

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figs.

  16. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, E.L.; Scharff, R.P.; Bauman, B.D.; Williams, M.A.

    1995-01-17

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figures.

  17. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, Edwin L.; Scharff, Robert P.; Bauman, Bernard D.; Williams, Mark A.

    1995-01-01

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  18. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, Edwin L.; Bauman, Bernard D.; Williams, Mark A.

    1996-04-09

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  19. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    Bauman, B.D.; Williams, M.A.; Bagheri, R.

    1997-12-02

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figs.

  20. Sprayed Coating Renews Butyl Rubber

    NASA Technical Reports Server (NTRS)

    Martin, R. B.

    1982-01-01

    Damaged butyl rubber products are renewed by spray technique originally developed for protective suits worn by NASA workers. A commercial two-part adhesive is mixed with Freon-113 (or equivalent) trichlorotrifluoroethane to obtain optimum viscosity for spraying. Mix is applied with an external-air-mix spray gun.

  1. CHEMICAL RECLAMATION OF SCRAP RUBBER

    EPA Science Inventory

    A conceptual, commercial-scale plant design was formulated for processing 22,500 t/yr of scrap rubber tires to hydrocarbon fuel gases, oils, petrochemicals (principally ethylene and aromatic liquids), and carbon black. The process is based upon molten salt (zinc chloride) pyrolys...

  2. Flow-Noise Calculation Using the Mutual Coupling Between Vulcanized Rubber and the Flow Around in Water

    NASA Astrophysics Data System (ADS)

    Li, Xue-Gang; Yang, Kun-De; Ma, Yuan-Liang

    2012-06-01

    A vulcanized rubber layer is usually used on the head of an axisymmetric body to keep it streamlined and watertight. The elastic boundary condition is considered when the flow noise of an axisymmetric body is calculated, and we employ the mutual coupling method between the vulcanized rubber layer and the flow around to solve the flow-noise field for an axisymmetric body in water. The results show that the deformation of the vulcanized rubber layer is reduced with the increase in Young's modulus. The Young's modulus of the rubber material should be large enough to keep it streamlined, and the noise power levels in the peak of the axisymmetric body are smaller than the other positions, which provides us with important theoretical support for laying acoustic arrays on the head of the body.

  3. Determination Of Mechanical Property Of Synthetic Rubber Using Optical Mouse As A Vibration Sensor

    NASA Astrophysics Data System (ADS)

    Gupta*, N.; Sharma, M.; Sarangi, S.; Bhattacharyya, R.

    Synthetic rubber is an incompressible isotropic hyper-elastic material. Its mechanical property is described only by rigidity modulus at undeformed configuration which is one third of Young's modulus at the same configuration. This paper describes an indirect method to determine its rigidity modulus by measuring the frequency of oscillation of a loaded rubber string. Small superimposed oscillation at static equilibrium stretch is measured with an optical mouse. The obtained data is processed to determine the frequency of oscillation. This process of acquiring data and processing it to obtain the desired information is known as Data Acquisition. Post processing and interpretation of the signal is done with help of MATLAB. The rigidity modulus of synthetic rubber is thus determined.

  4. On the two-potential constitutive modeling of rubber viscoelastic materials

    NASA Astrophysics Data System (ADS)

    Kumar, Aditya; Lopez-Pamies, Oscar

    2016-02-01

    This Note lays out the specialization of the two-potential constitutive framework - also known as the "generalized standard materials" framework - to rubber viscoelasticity. Inter alia, it is shown that a number of popular rubber viscoelasticity formulations, introduced over the years following different approaches, are special cases of this framework. As a first application of practical relevance, the framework is utilized to put forth a new objective and thermodynamically consistent rubber viscoelastic model for incompressible isotropic elastomers. The model accounts for the non-Gaussian elasticity of elastomers, as well as for the deformation-enhanced shear thinning of their viscous dissipation governed by reptation dynamics. The descriptive and predictive capabilities of the model are illustrated via comparisons with experimental data available from the literature for two commercially significant elastomers.

  5. Rubber lining for FGD scrubbers for waste incinerator plants

    SciTech Connect

    Rullmann, H.E.

    1999-11-01

    Flue gas desulfurization scrubbers for waste incineration plants can be lined with soft rubber or hard rubber for corrosion protection. Hard rubber is cured under high temperature and pressure in an autoclave. The advantage of hard rubber is the excellent temperature and chemical resistance. The authors have experience with hard rubber lined scrubbers that are in service without failures for over 20 years.

  6. The enzymatic synthesis of rubber polymer

    SciTech Connect

    Venkatachalam, K.V.; Wooten, L.; Benedict, C.R. )

    1990-05-01

    Washed rubber particles (WRP) isolated from stem homogenates of Parthenium argentatum by ultracentrifugation and gel filtration on columns of LKB Ultrogel AcA34 contain a tightly bound rubber transferase which catalyzes the polymerization of IPP into rubber polymer. The polymerization reaction requires Mg{sup 2+}, IPP and an allylic-PP. The Km values for Mg{sup 2+}, IPP and DMAPP are 5.2{times}10{sup {minus}4}M, 8.3{times}10{sup {minus}5} M and 9.6{times}10{sup {minus}5}M respectively. Gel permeation chromatography of the enzymatic polymer product on 3 linear columns of 1{times}10{sup 6} to 500 {angstrom} Ultrastyragel shows that the in vitro formed polymer has a similar mol wt to natural rubber. Over 90% of the in vitro formation of the rubber polymer was a de novo polymerization reaction from DMAPP initiator and IPP monomers. The bound rubber polymerase substantially differs from cytosolic rubber transferase which catalyzes only chain lengthening reactions. Treatment of the WRP with Chaps solubilized the bound rubber transferase which was further purified by DEAE-cellulose chromatography. The purified preparation primarily consists of a 52 kD polypeptide which binds to a photolabile substrate analog. The soluble rubber transferase catalyzes the synthesis of a 1{times}10{sup 5} mol wt rubber polymer from Mg{sup 2+}, DMAPP, IPP and detergent.

  7. Performance of diamond-like carbon-protected rubber under cyclic friction. I. Influence of substrate viscoelasticity on the depth evolution

    NASA Astrophysics Data System (ADS)

    Martinez-Martinez, D.; van der Pal, J. P.; Pei, Y. T.; De Hosson, J. Th. M.

    2011-12-01

    In this paper, the influence of the viscoelastic properties of rubber substrate on the tribological behavior of DLC film-coated alkyl acrylate rubber is studied. The mechanical behavior of the rubber was first characterized by creep experiments using spherical indentations. The results were adjusted using a delayed elasticity model, and a numerical simulation of the indentation of the sliding counterpart ball during the tribotest was carried out. The results show a progressive increase of the contact depth, which is in agreement with the experimental observations.

  8. Effects of filler modification and structuring on dielectric enhancement of silicone rubber composites

    NASA Astrophysics Data System (ADS)

    Javadi, Sara; Razzaghi-Kashani, Mehdi

    2013-04-01

    Preferred structuring of filler particles in a polymer matrix by using dielectrophoretic assembly process can enhance anisotropic dielectric properties. For this purpose, precipitated silica (SiO2) was structured in silicone rubber using an alternating electric field. This filler structure was stabilized by vulcanizing rubber during electric field application. Filler particle orientation and resulted anisotropy was verified by equilibrium swelling. Structuring filler in the rubber matrix led to increased dielectric permittivity and loss in the thickness direction. Filler surface modification by (vinyl-tris-(2- diethoxy/methoxy) silane) improved structure formation and anisotropic properties. It was shown that applying silane modifier and orientation of silica particles by dielectrophoretic assembly process increased dielectric permittivity of silicone rubber in the thickness direction while dielectric loss had either minor changes or increased less than permittivity in this direction. Although elastic modulus of composite, which was measured by dynamic-mechanical analysis, increased to some extent, enhancement in dielectric permittivity was much higher. This introduced the structured composite as a potential for dielectric elastomeric actuator with higher efficiency than the original silicone rubber with no filler addition.

  9. Thermomechanical characterisation of cellular rubber

    NASA Astrophysics Data System (ADS)

    Seibert, H.; Scheffer, T.; Diebels, S.

    2016-01-01

    This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.

  10. Compatibilizer for crumb rubber modified asphalt

    SciTech Connect

    Labib, M.E.; Memon, G.M.; Chollar, B.H.

    1996-12-31

    The United States of America discards more than 300 million tires each year, and out of that a large fraction of the tires is dumped into stock piles. This large quantity of tires creates an environmental problem. The use of scrap tires is limited. There is a usage potential in such fields as fuel for combustion and Crumb Rubber-Modified Asphalt binder (CRMA). The use of crumb rubber in modifying asphalt is not a new technique; it is been used since early 1960 by pavement engineers. Crumb rubber is a composite of different blends of natural and synthetic rubber (natural rubber, processing oils, polybutadiene, polystyrene butadiene, and filler). Prior research had concluded that the performance of crumb rubber modified asphalt is asphalt dependent. In some cases it improves the Theological properties and in some cases it degrades the properties of modified asphalt.

  11. Surgical rubber gloves impervious to methylmethacrylate monomer.

    PubMed

    Darre, E; Vedel, P

    1984-06-01

    Conventional surgical rubber gloves are permeable to the methylmethacrylate monomer (MMM) of acrylic bone cement. An in vitro technique was used which proved butyl rubber gloves, 0.48 mm thick, to be impervious to MMM. to avoid sensitization, butyl rubber gloves may be recommended to persons who are in contact with MMM. Such gloves should be worn by persons with known contact sensitization to MMM. PMID:6741470

  12. Blow molding of melt processible rubber

    SciTech Connect

    Abell, W.R.; Stuart, R.E.; Myrick, R.E.

    1991-07-01

    This article discusses the advantages of making hollow rubber parts by blow molding thermoplastic elastomers (TPEs) versus conventional rubber processing. It describes the various types of blow molding processes and it provides some insight into the rheological properties of melt processible rubber (MPR) and how MPR should be molded by each of these processes. A number of blow molded applications for MPR are also discussed.

  13. Rubber friction: comparison of theory with experiment.

    PubMed

    Lorenz, B; Persson, B N J; Dieluweit, S; Tada, T

    2011-12-01

    We have measured the friction force acting on a rubber block slid on a concrete surface. We used both unfilled and filled (with carbon black) styrene butadiene (SB) rubber and have varied the temperature from -10 °C to 100 °C and the sliding velocity from 1 μm/s to 1000 μm/s. We find that the experimental data at different temperatures can be shifted into a smooth master-curve, using the temperature-frequency shifting factors obtained from measurements of the bulk viscoelastic modulus. The experimental data has been analyzed using a theory which takes into account the contributions to the friction from both the substrate asperity-induced viscoelastic deformations of the rubber, and from shearing the area of real contact. For filled SB rubber the frictional shear stress σ(f) in the area of real contact results mainly from the energy dissipation at the opening crack on the exit side of the rubber-asperity contact regions. For unfilled rubber we instead attribute σ(f) to shearing of a thin rubber smear film, which is deposited on the concrete surface during run in. We observe very different rubber wear processes for filled and unfilled SB rubber, which is consistent with the different frictional processes. Thus, the wear of filled SB rubber results in micrometer-sized rubber particles which accumulate as dry dust, which is easily removed by blowing air on the concrete surface. This wear process seams to occur at a steady rate. For unfilled rubber a smear film forms on the concrete surface, which cannot be removed even using a high-pressure air stream. In this case the wear rate appears to slow down after some run in time period. PMID:22139094

  14. SOURCE ASSESSMENT: RUBBER PROCESSING, STATE OF THE ART

    EPA Science Inventory

    This report summarizes data on air emissions from the production of vulcanized elastomers (rubbers) and fabrication of rubber products. Hydrocarbons and particulates are emitted from various operations. Hydrocarbon emissions consist of monomers, rubber chemicals, and solvents whi...

  15. Recycling rubber wastes. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1995-02-01

    The bibliography contains citations concerning research and innovations in the recycling of rubber wastes. Recycling methods and equipment, applications of recycled rubber, and energy recovery systems and performance are among the topics discussed. Recycling methods compared and contrasted with various rubber waste disposal techniques are also included. (Contains a minimum of 96 citations and includes a subject term index and title list.)

  16. Recycling rubber wastes. (Latest citations from the rubber and plastics research association database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning research and innovations in the recycling of rubber wastes. Recycling methods and equipment, applications of recycled rubber, and energy recovery systems and performance are among the topics discussed. Recycling methods compared and contrasted with various rubber waste disposal techniques are also included. (Contains a minimum of 89 citations and includes a subject term index and title list.)

  17. Method for the addition of vulcanized waste rubber to virgin rubber products

    DOEpatents

    Romine, R.A.; Snowden-Swan, L.J.

    1997-01-28

    The invention is a method of using enzymes from thiophyllic microbes for selectively breaking the sulfur rubber cross-link bonds in vulcanized rubber. The process is halted at the sulfoxide or sulfone step so that a devulcanized layer is reactive with virgin rubber. 8 figs.

  18. The functional analyses of the cis-prenyltransferase and the rubber elongation factor in rubber biosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (cis-1,4-polyisoprene) is an essential plant derived commodity required for the manufacture of numerous industrial, medical and household items. Rubber is synthesized and sequestered on cytsolic vesicles known as rubber particles. When provided with farnesyl pyrophosphate (FPP) and is...

  19. Method for the addition of vulcanized waste rubber to virgin rubber products

    DOEpatents

    Romine, Robert A.; Snowden-Swan, Lesley J.

    1997-01-01

    The invention is a method of using enzymes from thiophyllic microbes for selectively breaking the sulfur rubber cross-link bonds in vulcanized rubber. The process is halted at the sulfoxide or sulfone step so that a devulcanized layer is reactive with virgin rubber.

  20. Ionic Modification Turns Commercial Rubber into a Self-Healing Material.

    PubMed

    Das, Amit; Sallat, Aladdin; Böhme, Frank; Suckow, Marcus; Basu, Debdipta; Wiessner, Sven; Stöckelhuber, Klaus Werner; Voit, Brigitte; Heinrich, Gert

    2015-09-23

    Invented by Charles Goodyear, chemical cross-linking of rubbers by sulfur vulcanization is the only method by which modern automobile tires are manufactured. The formation of these cross-linked network structures leads to highly elastic properties, which substantially reduces the viscous properties of these materials. Here, we describe a simple approach to converting commercially available and widely used bromobutyl rubber (BIIR) into a highly elastic material with extraordinary self-healing properties without using conventional cross-linking or vulcanising agents. Transformation of the bromine functionalities of BIIR into ionic imidazolium bromide groups results in the formation of reversible ionic associates that exhibit physical cross-linking ability. The reversibility of the ionic association facilitates the healing processes by temperature- or stress-induced rearrangements, thereby enabling a fully cut sample to retain its original properties after application of the self-healing process. Other mechanical properties, such as the elastic modulus, tensile strength, ductility, and hysteresis loss, were found to be superior to those of conventionally sulfur-cured BIIR. This simple and easy approach to preparing a commercial rubber with self-healing properties offers unique development opportunities in the field of highly engineered materials, such as tires, for which safety, performance, and longer fatigue life are crucial factors. PMID:26332010

  1. Dynamic Elasticity Model of Resilin Biopolymers

    NASA Astrophysics Data System (ADS)

    Hu, Xiao; Duki, Solomon

    2013-03-01

    Resilin proteins are `super elastic rubbers' in the flight and jumping systems of most insects, and can extend and retract millions of times. Natural resilin exhibits high resilience (> 95%) under high-frequency conditions, and could be stretched to over 300% of its original length with a low elastic modulus of 0.1-3 MPa. However, insight into the underlying molecular mechanisms responsible for resilin elasticity remains undefined. We report on the dynamic structure transitions and functions of full length resilin from fruit fly (D. melanogaster CG15920) and its different functional domains. A dynamic computational model is proposed to explain the super elasticity and energy conversion mechanisms of resilin, providing important insight into structure-function relationships for resilins, as well as other elastomeric proteins. A strong beta-turn transition was experimentally identified in the full length resilin and its non-elastic domains (Exon III). Changes in periodic long-range order were demonstrated during this transition, induced either by thermal or mechanical inputs, to confirm the universality of proposed mechanism. Further, this model offers new options for designing protein-based biopolymers with tunable material applications.

  2. Amino acid modifiers in guayule rubber compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tire producers are increasingly interested in biobased materials, including rubber but also as compounding chemicals. An alternative natural rubber for tire use is produced by guayule, a woody desert shrub native to North America. Alternative compounding chemicals include naturally-occurring amino a...

  3. Unraveling the Mystery of Natural Rubber Biosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (NR) is primarily obtained from Hevea brasiliensis, commonly known as the Brazilian rubber tree. As this species contains little genetic variation, it is susceptible to pathogen-based eradication. Consequently, it is imperative that a biomimetic pathway for NR production be developed....

  4. RADIATION INDUCED VULCANIZATION OF RUBBER LATEX

    DOEpatents

    Mesrobian, R.B.; Ballantine, D.S.; Metz, D.J.

    1964-04-28

    A method of vulcanizing rubber latex by exposing a mixture containing rubber latex and from about 15 to about 21.3 wt% of 2,5-dichlorostyrene to about 1.1 megarads of gamma radiation while maintaining the temperature of the mixture at a temperature ranging between from about 56 to about 59 deg C is described. (AEC)

  5. RUBBER-PROCESSING CHEMICALS DATA BASE

    EPA Science Inventory

    The objective of this research program was to compile a data base covering all the commercially significant organic rubber-processing chemicals produced or imported in the United States. The Rubber-Processing Chemicals Data Base contains the following elements: chemical informati...

  6. Biotechnological Development of Domestic Rubber Producing Crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber is an irreplaceable raw material vital to industry, transportation, medicine and defense, largely produced from clonal plantations of Hevea brasiliensis in South-east Asia. Additional rubber-producing crops are greatly desired to increase biodiversity, protect supplies, and provide a...

  7. Roughness Perception during the Rubber Hand Illusion

    ERIC Educational Resources Information Center

    Schutz-Bosbach, Simone; Tausche, Peggy; Weiss, Carmen

    2009-01-01

    Watching a rubber hand being stroked by a paintbrush while feeling identical stroking of one's own occluded hand can create a compelling illusion that the seen hand becomes part of one's own body. It has been suggested that this so-called rubber hand illusion (RHI) does not simply reflect a bottom-up multisensory integration process but that the…

  8. 75 FR 38119 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ... from Japan (38 FR 33593). Following five-year reviews by the Department of Commerce (``Commerce'') and... imports of polychloroprene rubber from Japan (64 FR 47765, September 1, 1999). Following second five-year... antidumping duty finding on imports of polychloroprene rubber from Japan (70 FR 44893). The Commission is...

  9. 75 FR 57980 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-23

    ... interested parties did not participate in this sunset review * * *.'' (75 FR 51981). Accordingly, pursuant to... COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION... whether revocation of the antidumping duty finding on polychloroprene rubber from Japan would be likely...

  10. Guayule: A Source of Natural Rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. Guayule's use as a natural rubber source dates before 1500 A.D. when Native Americans used its latex to make balls for games. Guayule has been evaluated in the U.S. as a commercial rubber crop during three per...

  11. Guayule: A Source of Natural Rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. Guayule’s use as a natural rubber source dates before 1500 A.D. when Native Americans used its latex to make balls for games. Guayule has been evaluated in the U.S. as a commercial rubber crop during three per...

  12. Zinc leaching from tire crumb rubber.

    PubMed

    Rhodes, Emily P; Ren, Zhiyong; Mays, David C

    2012-12-01

    Because tires contain approximately 1-2% zinc by weight, zinc leaching is an environmental concern associated with civil engineering applications of tire crumb rubber. An assessment of zinc leaching data from 14 studies in the published literature indicates that increasing zinc leaching is associated with lower pH and longer leaching times, but the data display a wide range of zinc concentrations, and do not address the effect of crumb rubber size or the dynamics of zinc leaching during flow through porous crumb rubber. The present study was undertaken to investigate the effect of crumb rubber size using the synthetic precipitation leaching procedure (SPLP), the effect of exposure time using quiescent batch leaching tests, and the dynamics of zinc leaching using column tests. Results indicate that zinc leaching from tire crumb rubber increases with smaller crumb rubber and longer exposure time. Results from SPLP and quiescent batch leaching tests are interpreted with a single-parameter leaching model that predicts a constant rate of zinc leaching up to 96 h. Breakthrough curves from column tests displayed an initial pulse of elevated zinc concentration (~3 mg/L) before settling down to a steady-state value (~0.2 mg/L), and were modeled with the software package HYDRUS-1D. Washing crumb rubber reduces this initial pulse but does not change the steady-state value. No leaching experiment significantly reduced the reservoir of zinc in the crumb rubber. PMID:23145882

  13. Cotton-Fiber-Filled Rubber Insulation

    NASA Technical Reports Server (NTRS)

    Anderson, Floyd A.

    1987-01-01

    Carbonization of fibers at high temperatures improves strength and erosion resistance. Cotton linters tested as replacement for asbestos filler currently used in rubber insulation in solid rocket motors. Cotton-filled rubber insulation has industrial uses; in some kinds of chemical- or metal-processing equipment, hoses, and protective clothing.

  14. Mesoscopic bead-and-spring model of hard spherical particles in a rubber matrix. I. Hydrodynamic reinforcement

    NASA Astrophysics Data System (ADS)

    Raos, Guido; Allegra, Giuseppe

    2000-11-01

    Exploiting an electrostatic analogy, we show that the elastic forces between a set of rigid particles embedded in a phantom polymer network can be represented by a simple bead-and-spring model. The beads represent the particles and the springs the rubber matrix. The model is validated by Monte Carlo simulation of rubbers filled with hard spherical particles, at volume fractions between 0.1 and 0.3. We derive both the moduli and the full stress-strain curves, under uniaxial elongation. The model reproduces and extends previous theoretical results on the so-called hydrodynamic reinforcement effect.

  15. Design of silicone rubber according to requirements based on the multi-objective optimization of chemical reactions

    SciTech Connect

    Jia Yuxi; Sun Sheng; Liu Lili; Mu Yue; An Lijia

    2004-08-16

    The explicit expression between composition and mechanical properties of silicone rubber was derived from the physics of polymer elasticity, the implicit expression among material composition, reaction conditions and reaction efficiency was obtained from chemical thermodynamics and kinetics, and then an implicit multi-objective optimization model was constructed. Genetic algorithm was applied to optimize material composition and reaction conditions, and the finite element method of cross-linking reaction processes was used to solve multi-objective functions, on the basis of which a new optimization methodology of cross-linking reaction processes was established. Using this methodology, rubber materials can be designed according to pre-specified requirements.

  16. Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

    NASA Astrophysics Data System (ADS)

    Kuntanoo, K.; Promkotra, S.; Kaewkannetra, P.

    2015-03-01

    A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (Tm) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.

  17. Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

    SciTech Connect

    Kuntanoo, K.; Promkotra, S.; Kaewkannetra, P.

    2015-03-30

    A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (T{sub m}) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.

  18. Elastic-resilience-induced dispersion of carbon nanotubes: a novel way of fabricating high performance elastomer.

    PubMed

    Wu, Siwu; Lin, Tengfei; Guo, Baochun

    2013-11-22

    State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs. PMID:24164916

  19. Elastic-resilience-induced dispersion of carbon nanotubes: a novel way of fabricating high performance elastomer

    NASA Astrophysics Data System (ADS)

    Wu, Siwu; Lin, Tengfei; Guo, Baochun

    2013-11-01

    State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs.

  20. High breakdown-strength composites from liquid silicone rubbers

    NASA Astrophysics Data System (ADS)

    Vudayagiri, Sindhu; Zakaria, Shamsul; Yu, Liyun; Sager Hassouneh, Suzan; Benslimane, Mohamed; Ladegaard Skov, Anne

    2014-10-01

    In this paper we investigate the performance of liquid silicone rubbers (LSRs) as dielectric elastomer transducers. Commonly used silicones in this application include room-temperature vulcanisable (RTV) silicone elastomers and composites thereof. Pure LSRs and their composites with commercially available fillers (an anatase TiO2, a core-shell TiO2-SiO2 and a CaCu3Ti4O12 filler) are evaluated with respect to dielectric permittivity, elasticity (Young’s modulus) and electrical breakdown strength. Film formation properties are also evaluated. The best-performing formulations are those with anatase TiO2 nanoparticles, where the highest relative dielectric permittivity of 5.6 is obtained, and with STX801, a core-shell morphology TiO2-SiO2 filler from Evonik, where the highest breakdown strength of 173 V μm-1 is obtained.

  1. Magnetic silicone rubber: Fabrication and analysis with applications

    NASA Astrophysics Data System (ADS)

    Fukushi, Takanori; Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi

    2013-08-01

    In this research, we fabricated magnetic silicone rubbers (MSR) by using magnetic powders of Fe or Sr ferrite ( ϕ 3-5 um) and investigated the physical properties of the MSR, such as the elastic and the magnetic characteristics. MSR is a new approach to flexible magnetic actuators. If the MSR is to be solidified, the mixing ratio between a silicone elastomer and the magnetic powders is important. In addition, the ratio determines the magnetic properties in a magnetic field. If soft magnetic powders are used in the MSR, magnetic force control is possible. We applied MSR to an electromagnetic linear actuator to verify the capability of MSR based on Fe or Sr ferrite materials. In the linear actuator for inchworm motion, MSR improved the magnetic force and the velocity. MSR can provide a simple mechanism for robotic applications and magnetic artificial muscles.

  2. History of Rubber and Its Use

    NASA Astrophysics Data System (ADS)

    Müller, Ingo; Strehlow, Peter

    Despite its spectacular properties rubber was not much good for anything before the latter part of the 19th century. To be sure the Aztecs had used it to make balls for their ceremonial ball games - or so we are told. But those games died along with the Aztec culture in the 16th century and there is no record of other useful applications until the late 18th century. But then, after that, rubber took off in a small way. After the American inventor Samuel Peal had obtained a patent in 1791 for the production of rubber-coated watertight textiles, the Scottish chemist Charles Macintosh (1766-1843) used such textiles for making rain-coats, and Thomas Hancock (1786-1865) produced rubber boots. At that time it was not really appropriate to speak of a rubber industry. What little material the evil-smelling workshops in New York and London needed, could be satisfied with the import of 30 tons of Caoutchouc1 annually - extracted from the sap of the tree Hevea brasiliensis - and most of that went for making erasers. Indeed, it had been reported by the English minister and scientist Joseph Priestley (1733-1804) that pieces of rubber are well-suited to rub out (sic!) pencil marks. Even today there is nothing better for the purpose and rubber became the English word for Caoutchouc.

  3. Zinc Leaching from Tire Crumb Rubber

    NASA Astrophysics Data System (ADS)

    Rhodes, E. P.; Ren, J.; Mays, D. C.

    2010-12-01

    Recent estimates indicate that more than 2 billion scrap tires are currently stockpiled in the United States and approximately 280 million more tires are added annually. Various engineering applications utilize recycled tires in the form of shredded tire crumb rubber. However, the use of tire crumb rubber may have negative environmental impacts, especially when the rubber comes into contact with water. A review of the literature indicates that leaching of zinc from tire crumb rubber is the most significant water quality concern associated with using this material. Zinc is generally used in tire manufacturing, representing approximately 1.3% of the final product by mass. This study will report results from the U.S. Environmental Protection Agency’s (EPA’s) Synthetic Precipitation Leaching Procedure, batch leaching tests, and column leaching tests performed to quantify the process by which zinc leaches from tire crumb rubber into water. Results are interpreted with a first-order kinetic attachment/detachment model, implemented with the U.S. Agricultural Research Service software HYDRUS-1D, in order to determine the circumstances when zinc leaching from tire crumb rubber would be expected to comply with the applicable discharge limits. One potential application for recycled tires is replacing sand with tire crumb rubber in granular media filters used for stormwater pollution control. For this to be a viable application, the total zinc in the stormwater discharge must be below the EPA’s benchmark value of 0.117 mg/L.

  4. Hyundai plans rubber unit despite overcapacity

    SciTech Connect

    Hyoungjin Kim

    1993-02-24

    Despite the oversupply of synthetic rubber in South Korea, the government has granted approval to Hyundai Petrochemical (Seoul) to build the country's second synthetic rubber unit, to be located alongside its petrochemical complex at Daesan. The plant is due for startup during second-half 1995, when the local market is expected to be in better balance. Hyundai will use Goodyear Tire Rubber technology for the plant, which will have annual capacities for 40,000 m.t. of polybutadiene rubber (BR), 30,000 m.t. of styrene butadiene rubber (SBR) and 12,000 m.t. of nitrile rubber (NBR). Styrene and butadiene requirements will be met from Hyundai's own production at Daesan. The current local producer of synthetic rubber is Korea Kumho Petrochemicals (Seoul), which has annual capacities for 150,000 m.t. of SBR, 95,000 m.t. of BR, and 10,000 m.t. of NBR. Korean SBR demand is about 141,000 m.t./year but is expected to increase to 161,000 m.t./year by 1996 and reach 194,000 m.t./year by the end of the decade.

  5. Damage of Elastomeric Matrix Composites (EMC-rubbers) Under Static Loading Conditions: Experimental and Numerical Study

    SciTech Connect

    Ayari, F.

    2011-01-17

    Elastomeric matrix composites (EMC-rubbers) are considered as isotropic hyper elastic incompressible materials under static loading conditions. As a rubber material element cannot be extended to an infinite stretch ratio, a damage mechanism at large strain is considered. The phenomenon of cavitation plays an important role in the damage of EMCs and influences the toughening mechanism of rubber-modified plastics. Indeed, cavitation in elastomers is thought to be initiated from flaws, which grow primarily due to a hydrostatic tensile stress and ahead of the crack; there will not only be a high stress perpendicular to the plane of the crack but also significant stress components in the other direction. However, there exists historically much discussion on the evolution of the cavitation in elastomers under monotonic and/or static solicitation. Mainly, cavitation instability occurs when the stress levels are sufficiently high so that the void expansion rate becomes infinitely large. Many research works have been performed to understand the effects of rubber cavitation on toughening of plastics. In fact, the cavitation phenomenon is not well known in detail. The most popular idea states that the cavitation is related to the existence of the gas bubbles trapped in the material during the production stage and the growing of the cavities would then be the result of the growing gas bubbles. Further, instable failure mechanism at the end of the cavitation is not well known too.

  6. Damage of Elastomeric Matrix Composites (EMC-rubbers) Under Static Loading Conditions: Experimental and Numerical Study

    NASA Astrophysics Data System (ADS)

    Ayari, F.; Bayraktar, E.; Zghal, A.

    2011-01-01

    Elastomeric matrix composites (EMC-rubbers) are considered as isotropic hyper elastic incompressible materials under static loading conditions. As a rubber material element cannot be extended to an infinite stretch ratio, a damage mechanism at large strain is considered. The phenomenon of cavitation plays an important role in the damage of EMCs and influences the toughening mechanism of rubber-modified plastics. Indeed, cavitation in elastomers is thought to be initiated from flaws, which grow primarily due to a hydrostatic tensile stress and ahead of the crack; there will not only be a high stress perpendicular to the plane of the crack but also significant stress components in the other direction. However, there exists historically much discussion on the evolution of the cavitation in elastomers under monotonic and/or static solicitation. Mainly, cavitation instability occurs when the stress levels are sufficiently high so that the void expansion rate becomes infinitely large. Many research works have been performed to understand the effects of rubber cavitation on toughening of plastics. In fact, the cavitation phenomenon is not well known in detail. The most popular idea states that the cavitation is related to the existence of the gas bubbles trapped in the material during the production stage and the growing of the cavities would then be the result of the growing gas bubbles. Further, instable failure mechanism at the end of the cavitation is not well known too.

  7. Thermal properties of hydrogenated liquid natural rubber

    SciTech Connect

    Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

    2015-09-25

    Natural rubber (NR) was modified to form liquid natural rubber (LNR) via photooxidative degradation. Hydrogenated liquid natural rubber (HLNR) was synthesized by using diimide as source of hydrogen which the diimide is produced by thermolysis of p-toluenesulfonyl hydrazide (TSH). The structure of HLNR was characterized by determining the changes of main peaks in Fourier Transform infrared and nuclear magnetic resonance spectra after hydrogenation. Thermogravimetric analysis showed that the HLNR had higher decomposition temperature compared to LNR and the decomposition temperature is directly proportional to the percentage of conversion.

  8. Thermal properties of hydrogenated liquid natural rubber

    NASA Astrophysics Data System (ADS)

    Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

    2015-09-01

    Natural rubber (NR) was modified to form liquid natural rubber (LNR) via photooxidative degradation. Hydrogenated liquid natural rubber (HLNR) was synthesized by using diimide as source of hydrogen which the diimide is produced by thermolysis of p-toluenesulfonyl hydrazide (TSH). The structure of HLNR was characterized by determining the changes of main peaks in Fourier Transform infrared and nuclear magnetic resonance spectra after hydrogenation. Thermogravimetric analysis showed that the HLNR had higher decomposition temperature compared to LNR and the decomposition temperature is directly proportional to the percentage of conversion.

  9. Chemistry of rubber processing and disposal.

    PubMed Central

    Bebb, R L

    1976-01-01

    The major chemical changes during the processing of rubber occur with the breakdown in mastication and during vulcanization of the molded tire. There is little chemical change during the compounding, calendering, extrusion, and molding steps. Reclaiming is the process of converting scrap rubber into an unsaturated, processible product that can be vulcanized with sulfur. Pyrolysis of scrap rubber yields a complex mixture of liquids, gas, and residue in varying ratios dependent on the nature of the scrap and the conditions of pyrolysis. PMID:799964

  10. Recycling rubber wastes. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1996-04-01

    The bibliography contains citations concerning research and innovations in the recycling of rubber wastes. Recycling methods and equipment, applications of recycled rubber, and energy recovery systems and performance are among the topics discussed. Recycling methods compared and contrasted with various rubber waste disposal techniques are also included. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  11. The rubber tree genome reveals new insights into rubber production and species adaptation.

    PubMed

    Tang, Chaorong; Yang, Meng; Fang, Yongjun; Luo, Yingfeng; Gao, Shenghan; Xiao, Xiaohu; An, Zewei; Zhou, Binhui; Zhang, Bing; Tan, Xinyu; Yeang, Hoong-Yeet; Qin, Yunxia; Yang, Jianghua; Lin, Qiang; Mei, Hailiang; Montoro, Pascal; Long, Xiangyu; Qi, Jiyan; Hua, Yuwei; He, Zilong; Sun, Min; Li, Wenjie; Zeng, Xia; Cheng, Han; Liu, Ying; Yang, Jin; Tian, Weimin; Zhuang, Nansheng; Zeng, Rizhong; Li, Dejun; He, Peng; Li, Zhe; Zou, Zhi; Li, Shuangli; Li, Chenji; Wang, Jixiang; Wei, Dong; Lai, Chao-Qiang; Luo, Wei; Yu, Jun; Hu, Songnian; Huang, Huasun

    2016-01-01

    The Para rubber tree (Hevea brasiliensis) is an economically important tropical tree species that produces natural rubber, an essential industrial raw material. Here we present a high-quality genome assembly of this species (1.37 Gb, scaffold N50 = 1.28 Mb) that covers 93.8% of the genome (1.47 Gb) and harbours 43,792 predicted protein-coding genes. A striking expansion of the REF/SRPP (rubber elongation factor/small rubber particle protein) gene family and its divergence into several laticifer-specific isoforms seem crucial for rubber biosynthesis. The REF/SRPP family has isoforms with sizes similar to or larger than SRPP1 (204 amino acids) in 17 other plants examined, but no isoforms with similar sizes to REF1 (138 amino acids), the predominant molecular variant. A pivotal point in Hevea evolution was the emergence of REF1, which is located on the surface of large rubber particles that account for 93% of rubber in the latex (despite constituting only 6% of total rubber particles, large and small). The stringent control of ethylene synthesis under active ethylene signalling and response in laticifers resolves a longstanding mystery of ethylene stimulation in rubber production. Our study, which includes the re-sequencing of five other Hevea cultivars and extensive RNA-seq data, provides a valuable resource for functional genomics and tools for breeding elite Hevea cultivars. PMID:27255837

  12. Micromorphological characterization and label-free quantitation of small rubber particle protein in natural rubber latex.

    PubMed

    Wang, Sai; Liu, Jiahui; Wu, Yanxia; You, Yawen; He, Jingyi; Zhang, Jichuan; Zhang, Liqun; Dong, Yiyang

    2016-04-15

    Commercial natural rubber is traditionally supplied by Hevea brasiliensis, but now there is a big energy problem because of the limited resource and increasing demand. Intensive study of key rubber-related substances is urgently needed for further research of in vitro biosynthesis of natural rubber. Natural rubber is biosynthesized on the surface of rubber particles. A membrane protein called small rubber particle protein (SRPP) is a key protein associated closely with rubber biosynthesis; however, SRPP in different plants has been only qualitatively studied, and there are no quantitative reports so far. In this work, H. brasiliensis was chosen as a model plant. The microscopic distribution of SRPP on the rubber particles during the washing process was investigated by transmission electron microscopy-immunogold labeling. A label-free surface plasmon resonance (SPR) immunosensor was developed to quantify SRPP in H. brasiliensis for the first time. The immunosensor was then used to rapidly detect and analyze SRPP in dandelions and prickly lettuce latex samples. The label-free SPR immunosensor can be a desirable tool for rapid quantitation of the membrane protein SRPP, with excellent assay efficiency, high sensitivity, and high specificity. The method lays the foundation for further study of the functional relationship between SRPP and natural rubber content. PMID:26844871

  13. The Pressure Curve for a Rubber Balloon.

    ERIC Educational Resources Information Center

    Merritt, D. R.; Weinhaus, F.

    1978-01-01

    Derives an equation relating the internal pressure of a rubber balloon to its radius. Shows that the theoretical pressure curve is experimentally verifiable, and discusses the problem of equilibrium configuration of two interconnected ballons. (Author/GA)

  14. Oils and rubber from arid land plants

    NASA Astrophysics Data System (ADS)

    Johnson, J. D.; Hinman, C. W.

    1980-05-01

    In this article the economic development potentials of Cucurbita species (buffalo gourd and others), Simmondsia chinensis (jojoba), Euphorbia lathyris (gopher plant), and Parthenium argentatum (guayule) are discussed. All of these plants may become important sources of oils or rubber.

  15. Rubber compounding materials -- ground coal. ASTM standard

    SciTech Connect

    1993-05-01

    This classification is under the jurisdiction of ASTM Committee on Rubber and is the direct responsibility of Subcommittee D11.20 on Compounding Materials and Procedures. The current edition was approved March 15, 1193 and published in May 1993.

  16. High frequency testing of rubber mounts.

    PubMed

    Vahdati, Nader; Saunders, L Ken Lauderbaugh

    2002-04-01

    Rubber and fluid-filled rubber engine mounts are commonly used in automotive and aerospace applications to provide reduced cabin noise and vibration, and/or motion accommodations. In certain applications, the rubber mount may operate at frequencies as high as 5000 Hz. Therefore, dynamic stiffness of the mount needs to be known in this frequency range. Commercial high frequency test machines are practically nonexistent, and the best high frequency test machine on the market is only capable of frequencies as high as 1000 Hz. In this paper, a high frequency test machine is described that allows test engineers to study the high frequency performance of rubber mounts at frequencies up to 5000 Hz. PMID:12071247

  17. Enhanced Stuffing Box Rubbers Test Report

    SciTech Connect

    Rochelle, J.

    2002-07-01

    The Rocky Mountain Oilfield Testing Center (RMOTC) and Scott's Oil Field Service tested an enhanced stuffing box rubber at the Naval Petroleum Reserve No. 3. The enhanced stuffing box rubbers have saved money from not having to replace packing as often and not spilling valuable oil on the ground. A reduction in environmental hazards and the cost of cleaning up spilled oil have also been a benefit.

  18. Exploring the thermodynamics of a rubber band

    NASA Astrophysics Data System (ADS)

    Roundy, David; Rogers, Michael

    2013-01-01

    We describe an upper-division experiment in thermal physics where students measure the tension of a rubber band as a function of temperature and length and use a Maxwell relation to find the change in internal energy and entropy for an isothermal stretch. This allows students to experimentally check the predictions of the entropic spring model for elastomers and observe that the entropy does indeed decrease as a rubber band is stretched.

  19. An Approximate Dissipation Function for Large Strain Rubber Thermo-Mechanical Analyses

    NASA Technical Reports Server (NTRS)

    Johnson, Arthur R.; Chen, Tzi-Kang

    2003-01-01

    Mechanically induced viscoelastic dissipation is difficult to compute. When the constitutive model is defined by history integrals, the formula for dissipation is a double convolution integral. Since double convolution integrals are difficult to approximate, coupled thermo-mechanical analyses of highly viscous rubber-like materials cannot be made with most commercial finite element software. In this study, we present a method to approximate the dissipation for history integral constitutive models that represent Maxwell-like materials without approximating the double convolution integral. The method requires that the total stress can be separated into elastic and viscous components, and that the relaxation form of the constitutive law is defined with a Prony series. Numerical data is provided to demonstrate the limitations of this approximate method for determining dissipation. Rubber cylinders with imbedded steel disks and with an imbedded steel ball are dynamically loaded, and the nonuniform heating within the cylinders is computed.

  20. Biomimetic surface-conducting silicone rubber obtained by physical deposition of MWCNT

    NASA Astrophysics Data System (ADS)

    Zylka, Pawel

    2015-06-01

    The paper presents a minimal approach to produce superhydrophobic, surface-conducting silicone rubber with a strongly developed surface modified with multiwall carbon nanotubes partially embedded in the silicone elastic matrix. The modification was achieved by physical deposition of carbon nanotube powder on a semi-liquid silicone rubber surface prior to its cross-linking. The resulting biomimetic material displayed superhydrophobic properties (static wetting angle >160°, sliding angle ∼10°), as well as elevated electric surface resistance (surface resistivity approx 18 kΩ). A piezoresistive hysteretic response with nonmonotonic change of the surface resistance accompanying substantial linear stretching was also demonstrated in the developed specimens displaying negative resistance change in a broad range of extension ratios, making them applicable as highly compliant, large-specific-area electrodes.

  1. Fabrication and electrical properties of metal-coated acrylate rubber microspheres by electroless plating

    NASA Astrophysics Data System (ADS)

    Gao, D. L.; Zhan, M. S.

    2009-01-01

    Electroless copper plating on micron-scale acrylate rubber (ACM) microspheres was studied. The core-shell structured Cu-coated ACM microspheres with high conductivity and low density were fabricated by introducing a reaction control method. Via multi-times activating treatment, the acrylate rubber (ACM) microspheres were implanted with more Ag catalytic active centers on the surfaces to promote the formation of coatings. The surface-coating structures and the electrical properties of Cu-coated ACM microspheres were investigated. It was found that the Cu-coated ACM microspheres were a kind of elastic particles. The different coating structures could be produced by controlling the extent of plating reaction. The coated microspheres with different coating structures were conductive, and their volume resistivities decreased remarkably with the increasing of applied pressure and varied with the temperature according to their surface coating structures.

  2. Rubber linings -- Overview and new technology

    SciTech Connect

    Mehra, L.; Polaski, E.L.; Lewis, R.K.; Mauri, A.

    1995-12-01

    The authors have covered at some length the basic steps involved in rubber lining. They have talked about the progress made in adhesives for lining. The new system in use now is far superior to previous systems. The new systems and the developments going on towards water-based adhesives are discussed. The authors briefly brought up the various types of rubber materials and new developments in terms of chlorobutyl-faced three-ply rubbers as well as development of EPDM-based compounds in Europe. The methods of vulcanization used have been discussed, including hot air vulcanizing which is prevalent in Europe. The development of self-vulcanizing rubber and the advantages in use of pre-cured rubber have been described. The development of new methods, techniques and products for rubber lining has been slow but sure. As can be expected, new product development costs are huge, requiring expert attention and participation. The possibilities are limitless and effort is forthcoming from various sources. There is a need for an interchange of ideas, and the involvement of NACE International and other professional bodies is acknowledged and appreciated.

  3. Adding crumb rubber into exterior wall materials.

    PubMed

    Zhu, Han; Thong-On, Norasit; Zhang, Xiong

    2002-10-01

    In Arizona US, most houses are built with walls covered by stuccos/coatings/mortars. This paper presents an explorative investigation of adding crumb rubber into stuccos/coatings/mortars. A series of experiments are conducted to examine the thermal and mechanical performance of the crumb rubber mixes. The results show that, the mixes with crumb rubber do exhibit more desirable performances like being high in crack-resistance and thermal insulation, and low in thermal expansion/contraction. The drawback for the crumb rubber mixes is the reduction in compressive strength, but which can be compensated by other means. As a site experiment, an area of 100 square-feet of crumb rubber coatings for two mix designs is sprayed on a tire-adobe wall. After being sprayed more than 14 months, the coatings apparently are in good condition. Significance of this study is that this practice, if accepted, will yield improved products that consume large quantities of crumb rubber. PMID:12498477

  4. Pseudo-Casimir stresses and elasticity of a confined elastomer film.

    PubMed

    Lu, Bing-Sui; Naji, Ali; Podgornik, Rudolf

    2016-05-11

    Investigations of the elastic behavior of bulk elastomers have traditionally proceeded on the basis of classical rubber elasticity, which regards chains as thermally fluctuating but disregards the thermal fluctuations of the cross-links. Herein, we consider an incompressible and flat elastomer film of an axisymmetric shape confined between two large hard co-planar substrates, with the axis of the film perpendicular to the substrates. We address the impact that thermal fluctuations of the cross-links have on the free energy of elastic deformation of the system, subject to the requirement that the fluctuating elastomer cannot detach from the substrates. We examine the behavior of the deformation free energy for one case where a rigid pinning boundary condition is applied to a class of elastic fluctuations at the confining surfaces, and another case where the same elastic fluctuations are subjected to soft "gluing" potentials. We find that there can be significant departures (both quantitative and qualitative) from the prediction of classical rubber elasticity theory when elastic fluctuations are included. Finally, we compare the character of the attractive part of the elastic fluctuation-induced, or pseudo-Casimir, stress with the standard thermal Casimir stress in confined but non-elastomeric systems, finding the same power law decay behavior when a rigid pinning boundary condition is applied; for the case of the gluing potential, we find that the leading order correction to the attractive part of the fluctuation stress decays inversely with the inter-substrate separation. PMID:27079513

  5. A calculation method for torsional vibration of a crankshafting system with a conventional rubber damper by considering rubber form

    SciTech Connect

    Kodama, Tomoaki; Honda, Yasuhiro; Wakabayashi, Katsuhiko; Iwamoto, Shoichi

    1996-09-01

    The cheap and compact rubber dampers of shear-type have been widely employed as the torsional vibration control of the crankshaft system of high-speed, automobile diesel engines. The conventional rubber dampers have various rubber forms owing to the thorough investigation of optimum dampers in the design stage. Their rubber forms can be generally grouped into three classes such as the disk type, the bush type and the composite type. The disk type and the bush type rubber dampers are called the basic-pattern rubber dampers hereafter. The composite type rubber part is supposed to consist of the disk type and the bush type parts, regarded respectively as the basic patterns of the rubber part, at large. The dynamic characteristics of the vibration isolator rubber depend generally on temperature, frequency, strain amplitude, shape and size effect,s so it is difficult to estimate accurately their characteristics. With the present technical level, it is also difficult to determine the suitable rubber geometry which optimizes the vibration control effect. The study refers to the calculation method of the torsional vibration of a crankshaft system with a shear-type rubber damper having various rubber forms in order to offer the useful method for optimum design. In this method, the rheological formula of the three-element Maxwell model, from which the torsional stiffness and the damping coefficient of the damper rubber part in the equivalent vibration system are obtained, are adopted in order to decide the dynamic characteristics of the damper rubber part.

  6. Combination biological and microwave treatments of used rubber products

    DOEpatents

    Fliermans, Carl B.; Wicks, George G.

    2002-01-01

    A process and resulting product is provided in which a vulcanized solid particulate, such as vulcanized crumb rubber, has select chemical bonds altered by biotreatment with thermophillic microorganisms selected from natural isolates from hot sulfur springs. Following the biotreatment, microwave radiation is used to further treat the surface and to treat the bulk interior of the crumb rubber. The resulting combined treatments render the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels and sizes of the treated crumb rubber can be used in new rubber mixtures and good properties obtained from the new recycled products.

  7. Preliminary validation of Sm-Fe-N magnetic silicone rubber for a flexible magnetic actuator

    NASA Astrophysics Data System (ADS)

    Fukushi, Takanori; Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi

    2014-06-01

    In this paper, we present a new approach for a flexible magnetic actuator (FMA) using Sm-Fe-N magnetic silicone rubber (MSR) that has a higher degree of freedom (DOF) in shape, flexibility, ease of fabrication and combinative ability than permanent magnets. To verify its potential for use in an FMA, we examined its magnetic and elastic properties and focused on magnetic torque control within a uniform rotating magnetic field. Silicone rubber liquid and hardener were mixed with Sm-Fe-N powder and poured into a mold. The fabricated Sm-Fe-N MSR included Sm-Fe-N powder of 13.5, 17.3, and 21.2 vol% ratio. The physical and elastic properties were determined by a vibrating sample magnetometer (VSM) and elastic load, respectively. Furthermore, we fabricated two FMAs (multiple-magnetic anisotropy type and spiral-type), and evaluated the suitability of the Sm-Fe-N MSR for magnetic wireless actuators based on magnetic torque control.

  8. Elastic properties of hollow colloidal particles

    NASA Astrophysics Data System (ADS)

    Zoldesi, C. I.; Ivanovska, I. L.; Quilliet, C.; Wuite, G. J. L.; Imhof, A.

    2008-11-01

    The elastic properties of micrometer-sized hollow colloidal particles obtained by emulsion templating are probed by nanoindentation measurements in which point forces are applied to solvent-filled particles supported on a flat substrate. We show that the shells respond linearly up to forces of 7-21nN , where the indentation becomes of the order of the shell thickness (20-40nm) . In the linear region, the particle deformation is reversible. The measured Young’s modulus (˜200MPa) is comparable to values for stiff rubbers or soft polymers. At larger applied force, we observe a crossover into a nonlinear regime, where the shells assume a buckled shape. Here, the force increases approximately as the square root of the indentation, in agreement with the theory of elasticity of thin shells. We also observe permanent deformation of the shells after probing them repetitively beyond the linear regime. Finally, the measured elastic properties of the shells nicely explain their spontaneous buckling in solution and due to drying.

  9. New rubber qualification for the igniter adapter

    NASA Technical Reports Server (NTRS)

    Humpherys, Mark A.

    1994-01-01

    Kirkhill Rubber Company (KRC) has informed Thiokol Corporation that two raw materials used in the asbestos and silica filled acrylonitrile butadience rubber (NBR) formulation per STW 2621 are no longer available from their vendors. Agerite White (Di-beta-naphthyl-paraphenylene diamine), manufactured by B. F. Goodrich, is an antioxidant used in NBR. This raw material makes up roughly 1-2 percent of the finished product. KRC proposed that this raw material be replaced by Agerite Stalite S (mixture of octylated diphenylamines) distributed by R. T. Vanderbilt Co. Protox-166 zinc oxide, manufactured by Zinc Corporation of America, is an activator currently used in NBR. This material also makes up about 1-2 percent of the finished material. Protox-166 is an American process grade zinc oxide. It is proposed by KRC to replace Protox-166 with Kadox-930C, a French process grade zinc oxide. American process grades have an ASTM minimum purity of 99.0 percent; the French process grades have a minimum purity of 99.5 percent. Previous testing per WTP-0270 has demonstrated that the mechanical and thermal properties of the rubber with the new ingredients are comparable to the 'old' rubber. The test results are reported in TWR-61790. One igniter adapter, Part no. 7U77562-02 serial no. 2 was insulated per ETP-1206 using the new rubber formulation and a modified lay up and cure method to demonstrate that there is no impact on this process. The results of this demonstration are reported.

  10. Investigation of natural latex rubber gloves

    SciTech Connect

    Vessel, E.M.

    1993-03-19

    Seventy five percent of natural latex rubber gloves used in laboratories at the Savannah River Site are not reused. A cost analysis performed by the SRS Procurement Department determined that a net savings of $1,092,210 could be achieved annually by recycling latex rubber gloves. The Materials Technology Section, at the request of the Procurement Department, examined some mechanical and chemical properties of latex rubber gloves manufactured by Ansell Edmont, which had been purchased by the site specifications for protective clothing. It also examined mechanical properties of re-cycled gloves purchased by specifications and of {open_quotes}off the shelf{close_quotes} gloves manufactured by North Brothers Company. Finally, water vapor transmission studies, simulating tritium permeation, were performed on gloves from both manufacturers. These studies were performed to determine whether latex rubber gloves can be recycled or whether using only new, unwashed gloves is required in areas where tritium exposure is a possibility. The results of these studies indicate that the acceptable glove characteristics, required in the WSRC Manual 5Q1.11, Protective Clothing Specifications, are not adversely affected after washing and drying the gloves manufactured by Ansell Edmont for seven cycles. Results also indicate that natural latex rubber gloves manufactured by North Brothers comply with most of the acceptable glove characteristics specified in the WSRC Manual 5Q1.11. Statistical analysis of the water vapor permeation data show that there is no correlation between permeation rates and the manufacturer.

  11. On Optimizing an Archibald Rubber-Band Heat Engine.

    ERIC Educational Resources Information Center

    Mullen, J. G.; And Others

    1978-01-01

    Discusses the criteria and procedure for optimizing the performance of Archibald rubber-band heat engines by using the appropriate choice of dimensions, minimizing frictional torque, maximizing torque and balancing the rubber band system. (GA)

  12. Evaluation of synergy in tire rubber-coal coprocessing

    SciTech Connect

    Mastral, A.M.; Mayoral, M.C.; Murillo, R.; Callen, M.; Garcia, T.; Tejero, M.P.; Torres, N.

    1998-09-01

    The tire rubber-coal synergy is evaluated through the different roles that rubber can have in coprocessing systems. For that, two different experimental designs were used: a swept fixed-bed reactor and tubing bomb minireactors. In this way, coal was coprocessed with rubber liquids from rubber pyrolysis and rubber hydrogenation, in a hydrogen atmosphere at 400 C. Coal was mixed as well with rubber in different proportions and hydrogenated at 375, 400, and 425 C, and oils obtained were characterized by thin-layer chromatography to obtain hydrocarbon type composition. Rubber behavior was compared to each of the main components of tires, and all the results indicated that the slight synergy found can be due to the small free radicals from vulcanized rubber decomposition, which are able to stabilize coal radicals to light products.

  13. Insulation of nonlinear and random vibrations in the mining industry. [elastodynamic response of rubber insulator

    NASA Technical Reports Server (NTRS)

    Zeveleanu, C.

    1974-01-01

    The insulation of nonlinear and random vibrations is considered for some ore preparing and sorting implements: rotary crushers, resonance screens, hammer mills, etc. The appearance of subharmonic vibrations is analyzed, and the conditions for their appearance are determined. A method is given for calculating the insulation of these vibrations by means of elastic elements made of rubber. The insulation of the random vibrations produced by Symons crushers is calculated by determining the transmissability and deformation of the insulation system for a narrow band random response.

  14. Estimating the Degree of Cross-Linking in Rubber

    NASA Technical Reports Server (NTRS)

    Fedors, R. F.

    1983-01-01

    Degree of cross-linking or network chain concentration of rubber estimated with aid of new method. Quantity is needed in studies of mechanical behavior of rubber. New method is based on finding rubber follows different stress/ strain relationships in extension and retraction. When rubber specimen is stretched to given extension ration and released. Stress-vs-strain curve follows two paths: one for extension and other for retraction.

  15. Effects of preparation process on performance of rubber modified asphalt

    NASA Astrophysics Data System (ADS)

    Liu, Hanbing; Luo, Guobao; Wang, Xianqiang; Jiao, Yubo

    2015-06-01

    The rational utilization of waste rubber tire is essential for the environmental protection. Utilizing rubber particles to modify asphalt can not only improve asphalt performance, but also help the recycling of waste materials. Considering the effect of different preparation process parameters on the performance of rubber modified asphalt, this paper analyzes the effects of the shear temperature, shear time and shear rate on the performance of rubber modified asphalt, and provided a reference for its preparation.

  16. Use of scrap rubber in asphalt pavement surfaces

    NASA Astrophysics Data System (ADS)

    Eaton, Robert A.; Roberts, Richard J.; Blackburn, Robert R.

    1991-12-01

    Scrap tire rubber was mixed into an asphalt concrete wearing course to study the effect of ice disbonding from the pavement surface under traffic. Rubber contents of 0, 3, 6, and 12 percent by weight were studied. Initial laboratory ice disbonding test results led to the development of a new paving material, Chunk Rubber Asphalt Concrete (CRAC), that uses larger pieces of rubber in a much denser asphalt concrete mix. Strength values doubled and ice disbonding performance was enhanced.

  17. [Contemporary state of work conditions and occupational morbidity of workers engaged into rubber, mechanical rubber and tire industries].

    PubMed

    Stepanov, E G; Galiullina, É F; Samsonov, V M; Kudriavtsev, V P; Davletgareeva, G R; Shakirova, É D; Khasanov, B G; Buliakov, R T; Kamilov, R F; Shakirov, D F

    2014-01-01

    Based on analysis of materials provided by occupational safety department PC "UZEMiK" and JSC "Kauchuk", the authors evaluate contemporary work conditions and occupational morbidity in workers engaged into rubber, mechanical rubber and tyre industries. PMID:25335420

  18. Anaerobic desulfurization of ground rubber with the thermophilic archaeon Pyrococcus furiosus--a new method for rubber recycling.

    PubMed

    Bredberg, K; Persson, J; Christiansson, M; Stenberg, B; Holst, O

    2001-01-01

    The anaerobic sulfur-reducing archaeon Pyrococcus furiosus was investigated regarding its capacity to desulfurize rubber material. The microorganism's sensitivity towards common rubber elastomers and additives was tested and several were shown to be toxic to P. furiosus. The microorganism was shown to utilize sulfur in vulcanized natural rubber and an increase in cell density was obtained when cultivated in the presence of spent tire rubber. Ethanol-leached cryo-ground tire rubber treated with P. furiosus for 10 days was vulcanized together with virgin rubber material (15% w/w) and the mechanical properties of the resulting material were determined. The increase in the stress at break value and the decrease in swell ratio and stress relaxation rate obtained for material containing microbially treated rubber (compared to untreated material) show the positive effects of microbial desulfurization on rubber. PMID:11234957

  19. Anomalous crack propagation in reinforced natural rubber

    NASA Astrophysics Data System (ADS)

    Sotta, Paul; Gabrielle, Brice; Long, Didier; Vanel, Loic; Albouy, Pierre-Antoine; Peditto, Francesca

    2009-03-01

    In reinforced natural rubber, crack propagation in mode I exhibits rotation of the tear in a direction perpendicular to the usual one. Our objective is, first, to understand the impact of this phenomenon on fracture toughness of the material, and, secondly, to understand how this phenomenon is related to the specific properties of reinforced natural rubber. To this aim, we combine measurements of ultimate properties, measurements of the number and length of tear rotations as a function of loading velocity and temperature, and investigation of material heterogeneities at sub-micrometric scales, originating both from fillers and strain-induced crystallites (strain-induced crystallinity is measured up to failure by X ray diffraction), in natural rubber samples reinforced by nanometric aggregates. Observations suggest that tear rotation is related both to the mechanical anisotropy induced by strain-induced crystallinity and to the dissipative properties of the material at high strain.

  20. Coatings for rubber bonding and paint adhesion

    NASA Astrophysics Data System (ADS)

    Boulos, M. S.; Petschel, M.

    1997-08-01

    Conversion coatings form an important base for the adhesion of paint to metal substrates and for the bonding of rubber to metal parts. Four types of conversion coatings were assessed as base treatments for the bonding of rubber to steel and for the corrosion protection of metal substrates under paint: amorphous iron phosphate, heavy zinc phosphate, and three types of modified zinc phosphates that utilized one or more metal cations in addition to zinc. When applied, these conversion coatings formed a thin film over the metal substrate that was characterized by scanning electron microscopy, x-ray diffraction, and chemical methods. The performance of the coatings was assessed using physical methods such as dry adhesion, conical mandrel, impact, and stress adhesion for the rubber-bonded parts, and by corrosion resistance methods such as humidity, salt spray, and cyclic corrosion. Coating characterization and performance were correlated.

  1. Modified Silicone-Rubber Tooling For Molding Composite Parts

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.; Snoha, John J.; Weiser, Erik S.

    1995-01-01

    Reduced-thermal-expansion, reduced-bulk-modulus silicone rubber for use in mold tooling made by incorporating silica powder into silicone rubber. Pressure exerted by thermal expansion reduced even further by allowing air bubbles to remain in silicone rubber instead of deaerating it. Bubbles reduce bulk modulus of material.

  2. Bonding soft rubber or plasticized elastomers to metal

    NASA Technical Reports Server (NTRS)

    Clemons, J. M.; Ledbetter, F. E., III; White, W. T.

    1980-01-01

    Approach using bond-cover coat of unplasticized rubber between soft rubber and adhesive eliminates diffusion problem. Approach is useful in making improved seals in automobile engines, industrial and public plumbing, and in other areas using soft-rubber-to-metal bonds. Seals and gaskets made this way would not have to be replaced very often, reducing cost of maintenance.

  3. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Rubber gloves; minimum requirements. 77.606-1... COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves (lineman's... be used and tested in accordance with the provisions of §§ 77.704-6 through 77.704-8. (b)...

  4. A sustainability review of domestic rubber from the guayule plant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is an arid-adapted, low-input perennial shrub native to Mexico and southern Texas that has received considerable attention as an alternative source of natural rubber. It has potential to replace the most common types of rubbers, including synthetic rubber derived...

  5. Natural Rubber Biosynthesis and a Profitable Guayule Crop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (cis-1,4-polyisoprene) is a biopolymer apparently synthesized in plants by a membrane-bound rubber transferase protein complex. The kinetic features of rubber transfereases make them a distinct class of cis-prenyl transferases. The structure of the particular allylic pyrophosphate in...

  6. Development of Crops To Produce Industrially Useful Natural Rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber, cis-1,4-polyisoprene, is an essential industrial commodity that most developed countries have to import. Hevea brasiliensis, grown in tropical and subtropical areas is the primary source of natural rubber. The goal of our work is to develop rubber-producing crops suitable for culti...

  7. Development of crops to produce industrially useful natural rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber, cis-1,4-polyisoprene, is an essential industrial commodity that most developed countries have to import. Hevea brasiliensis (Hevea), grown in tropical and subtropical areas is the primary source of natural rubber. The high quality and quantity of the rubber cause us to focus on und...

  8. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Rubber gloves; minimum requirements. 77.606-1... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves...

  9. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rubber gloves; minimum requirements. 77.606-1... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves...

  10. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Rubber gloves; minimum requirements. 77.606-1... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves...

  11. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Rubber gloves; minimum requirements. 77.606-1... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves...

  12. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative....

  13. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative....

  14. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative....

  15. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative....

  16. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative....

  17. Interface interactions of natural rubber and protein/fiber aggregates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mechanical properties of natural rubber are improved with a renewable filler for rubber applications. Aggregates of protein and fiber that constitute soy protein concentrate were shear-reduced and used to enhance the tensile modulus of the natural rubber. The aqueous dispersion of the shear-reduced ...

  18. Coliquefaction of waste rubber tires with coal

    SciTech Connect

    Orr, E.C.; Tuntawiroon, W.

    1994-12-31

    There is an interest in the conversion of coal to liquid fuels because of the abundant supply of coal and the diminishing reserves of petroleum. Standard coal liquefaction techniques utilize H{sub 2} gas as a source of hydrogen to cap the radical species produced during liquefaction. Waste materials such as plastics, oils, and rubber tires with a high hydrogen content could be an alternative source of hydrogen that, in principle, could be transferred from the waste materials to the coal during liquefaction. An added benefit of such a program of waste material utilization would be a diminution in materials disposed of in landfills or incinerators. Rubber tires are approximately one third by weight carbon black. Farcasiu and Smith have shown that carbon black increases yields in coal liquefaction. Since carbon black is one of the top fifty chemicals produced in America during 1993 (3.22 billion pounds) the recovery and reuse of carbon black from tires could become economically attractive. Giavarini has shown in recent work that carbon black could be reclaimed and activated to produce quality carbon blacks after pyrolyzing waste rubber tires. Rubber tires also contain zinc oxide which is added as a filler and also aids in the vulcanization of the rubber. Waste plastics contain many metals used for coloring, waste oils contain metals acquired while used as a lubricant, and waste rubber tires contain zinc. A past investigation suggested that coal undergoing liquefaction may act as a {open_quotes}scavenger{close_quotes} for heavy metals. The ability of coal to trap metals will be discussed in the present paper. Electron probe microanalysis (EPMA) is a technique which can map the dispersion of an element within a sample by the detection of characteristic X-rays. Using EPMA, samples of the insoluble fraction produced by the coliquefaction experiments were analyzed to determine whether several heavy elements of interest were trapped in coal particles.

  19. Nonlinear elasticity, fluctuations and heterogeneity of nematic elastomers

    SciTech Connect

    Xing Xiangjun Radzihovsky, Leo

    2008-01-15

    Liquid crystal elastomers realize a fascinating new form of soft matter that is a composite of a conventional crosslinked polymer gel (rubber) and a liquid crystal. These solid liquid crystal amalgams, quite similarly to their (conventional, fluid) liquid crystal counterparts, can spontaneously partially break translational and/or orientational symmetries, accompanied by novel soft Goldstone modes. As a consequence, these materials can exhibit unconventional elasticity characterized by symmetry-enforced vanishing of some elastic moduli. Thus, a proper description of such solids requires an essential modification of the classical elasticity theory. In this work, we develop a rotationally invariant, nonlinear theory of elasticity for the nematic phase of ideal liquid crystal elastomers. We show that it is characterized by soft modes, corresponding to a combination of long wavelength shear deformations of the solid network and rotations of the nematic director field. We study thermal fluctuations of these soft modes in the presence of network heterogeneities and show that they lead to a large variety of anomalous elastic properties, such as singular length-scale dependent shear elastic moduli, a divergent elastic constant for splay distortion of the nematic director, long-scale incompressibility, universal Poisson ratios and a nonlinear stress-strain relation for arbitrary small strains. These long-scale elastic properties are universal, controlled by a nontrivial zero-temperature fixed point and constitute a qualitative breakdown of the classical elasticity theory in nematic elastomers. Thus, nematic elastomers realize a stable 'critical phase', characterized by universal power-law correlations, akin to a critical point of a continuous phase transition, but extending over an entire phase.

  20. The role of the small rubber particle protein in determining rubber yields and polymer length in Russian dandelion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several proteins have been identified and implicated in natural rubber biosynthesis, one of which, the small rubber particle protein (SRPP), was originally identified in Hevea brasiliensis as an abundant protein associated with cytosolic vesicles known as rubber particles. While previous in vitro s...

  1. Kinetics of zinc release from ground tire rubber and rubber ash in a calcareous soil as alternatives to Zn fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ground rubber contains 15-20 g Zn/kg but very low levels of Cd and could serve as an inexpensive byproduct Zn fertilizer. The aim of this investigation was to test the kinetics of Zn release in a soil treated with ground tire rubber and rubber ash compared with commercial Zn fertilizer and a labora...

  2. Radiation-induced vulcanisation of natural rubber latex in presence of styrene-butadiene rubber latex

    NASA Astrophysics Data System (ADS)

    Chaudhari, C. V.; Bhardwaj, Y. K.; Patil, N. D.; Dubey, K. A.; Kumar, Virendra; Sabharwal, S.

    2005-04-01

    Radiation vulcanisation of natural rubber latex in presence of styrene butadiene rubber latex (SBRL) has been investigated. The cast films were characterised for their swelling properties, tensile strength and thermal stability as a function of radiation dose as well as SBRL content. The gel content, tensile strength and thermal stability of the copolymer films were found to increase with increasing the SBRL content in the feed solution and radiation dose.

  3. Enzymatic synthesis of rubber polymer in Hevea brasiliensis

    SciTech Connect

    Tang, F.; Hu, S.; Benedict, C.R. )

    1991-05-01

    Light and Dennis purified serum soluble rubber transferase from Hevea latex to homogeneity. Prenyl transferase co-purified with rubber transferase. In the absence of washed rubber particles (WRP) the prenyl transferase catalyzed the formation of trans FPP from DMAPP and IPP. In the presence of WRP the transferase catalyzed cis additions of IPP to pre-existing rubber chains. Control mixtures of WRP, Mg{sup 2+} and FPP were not included to test for the contributions of the bound rubber transferase on WRP to the incorporation of IPP into polyisoprene. Bound rubber transferase catalyzes the repetitive addition of IPP to allylic-PP starter molecules to form polyisoprene. The order of utilization of allylic-PP starters was GGPP > FPP > GPP > DMAPP. The authors have shown that the polyisoprene enzymatically synthesized on WRP is a bimodal polymer consisting of different mol wt rubber chains similar to the polymeric characteristics of natural rubber. The bound rubber transferase was solubilized with Chaps and purified on DEAE-cellulose. The polymerization reaction catalyzed by the purified preparation showed a 98% requirement for pre-existing rubber chains. Results suggest that the prenyl transferase from Hevea serum may be part of the polymer starter system furnishing allylic-PP for the bound rubber transferase.

  4. Natural rubber (NR) biosynthesis: perspectives from polymer chemistry

    SciTech Connect

    Barkakaty, Balaka

    2014-01-01

    Natural rubber is an important strategic raw material for manufacturing a wide variety of industrial products. There are at least 2,500 different latex-producing plant species; however, only Hevea brasiliensis (the Brazilian rubber tree) is a commercial source. The chemical structure of natural rubber is cis-1,4-polyisoprene, but the exact structure of the head and end groups remains unknown. Since synthetic cis-1,4-polyisoprenes cannot match the superior properties of natural rubber, understanding the chemistry behind the biosynthetic process is key to finding a possible replacement. T his chapter summarizes our current understandings from the perspective of a polymer scientist by comparing synthetic polyisoprenes to natural rubber. The chapter also highlights biomimetic polymerization, research towards a synthetic match of natural rubber and the role of natural rubber in health care.

  5. The rubber tree genome shows expansion of gene family associated with rubber biosynthesis

    PubMed Central

    Lau, Nyok-Sean; Makita, Yuko; Kawashima, Mika; Taylor, Todd D.; Kondo, Shinji; Othman, Ahmad Sofiman; Shu-Chien, Alexander Chong; Matsui, Minami

    2016-01-01

    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis’s capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree. PMID:27339202

  6. Preparation of sulfonic acid-containing rubbers from natural rubber vulcanizates

    NASA Astrophysics Data System (ADS)

    Poonsawat, Worapong; Poompradub, Sirilux; Ngamcharussrivichai, Chawalit

    2014-06-01

    In this work, a series of sulfonic acid-containing rubbers were prepared by aqueous phase oxidation of natural rubber vulcanizates in the presence of hydrogen peroxide (H2O2) and formic acid (HCOOH). The starting vulcanizates were neatly prepared via an efficient vulcanization (EV) system by varying mass ratio of N-cyclohexyl-2-benzothiazole sulfonamide (CBS), as an accelerator, to sulfur. The oxidation conditions were controlled at the molar ratio of H2O2: HCOOH = 1:1, the concentration of H2O2 = 15 wt.%, the temperature = 50 °C, and the reaction time = 3 h. The rubber materials before and after the oxidation were characterized for their physicochemical properties by using Fourier transform infrared spectroscopy, bomb calorimetry, acid-base titration and swelling measurements. The results indicated the presence of sulfonic acid group in the oxidized rubbers, generated by the oxidative cleaves of sulfide crosslinks in the rubber vulcanizates. The oxidation decreased the sulfur content of the rubber in which the level of sulfur loss was determined by the CBS/sulfur ratio. Moreover, the acidity of the oxidized products was correlated with the amount of sulfur remaining.

  7. Hardness and compression resistance of natural rubber and synthetic rubber mixtures

    NASA Astrophysics Data System (ADS)

    Arguello, J. M.; Santos, A.

    2016-02-01

    This project aims to mechanically characterize through compression resistance and shore hardness tests, the mixture of hevea brasiliensis natural rubber with butadiene synthetic rubber (BR), styrene-butadiene rubber (SBR) and ethylene-propylene-diene monomer rubber (EPDM). For each of the studied mixtures were performed 10 tests, each of which increased by 10% the content of synthetic rubber in the mixture; each test consisted of carrying out five tests of compression resistance and five tests of shore hardness. The specimens were vulcanized on a temperature of 160°C, during an approximate time of 15 minutes, and the equipment used in the performance of the mechanical tests were a Shimadzu universal machine and a digital durometer. The results show that the A shore hardness increases directly proportional, with a linear trend, with the content of synthetic BR, SBR or EPDM rubber present in the mixture, being the EPDM the most influential. With respect to the compression resistance is observed that the content of BR or SBR increase this property directly proportional through a linear trend; while the EPDM content also increases but with a polynomial trend.

  8. The rubber tree genome shows expansion of gene family associated with rubber biosynthesis.

    PubMed

    Lau, Nyok-Sean; Makita, Yuko; Kawashima, Mika; Taylor, Todd D; Kondo, Shinji; Othman, Ahmad Sofiman; Shu-Chien, Alexander Chong; Matsui, Minami

    2016-01-01

    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis's capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree. PMID:27339202

  9. Carboxy terminated rubber based on natural rubber grafted with acid anhydrides and its adhesion properties

    NASA Astrophysics Data System (ADS)

    Klinpituksa, P.; Kongkalai, P.; Kaesaman, A.

    2014-08-01

    The chemical modification of natural rubber by grafting of various polar functional molecules is an essential method, improving the versatility of rubber in applications. This research investigated the preparation of natural rubber-graft-citraconic anhydride (NR-g-CCA), natural rubber-graft-itaconic anhydride (NR-g-ICA), and natural rubber-graft-maleic anhydride (NR-g-MA), with the anhydrides grafted to natural rubber in toluene using benzoyl peroxide as an initiator. Variations of monomer content, initiator content, temperature and reaction time of the grafting copolymerization were investigated. The maximum degrees of grafting were 1.06% for NR-g-CCA, 4.66% for NR-g-ICA, and 5.03% for NR-g-MA, reached using 10 phr citraconic anhydride, 10 phr of itaconic anhydride, or 8 phr of maleic anhydride, 3 phr benzoyl peroxide, at 85, 80 and 80°C for 2, 2 and 3 hrs, respectively. Solvent-based wood adhesives were formulated from these copolymers with various contents of wood resin in the range 10-40 phr. The maximal 289 N/in cleavage peel and 245.7 KPa shear strength for NR-g-MA (5.03% grafting) were obtained at 40 phr wood resin.

  10. Beta Backscatter Measures the Hardness of Rubber

    NASA Technical Reports Server (NTRS)

    Morrissey, E. T.; Roje, F. N.

    1986-01-01

    Nondestructive testing method determines hardness, on Shore scale, of room-temperature-vulcanizing silicone rubber. Measures backscattered beta particles; backscattered radiation count directly proportional to Shore hardness. Test set calibrated with specimen, Shore hardness known from mechanical durometer test. Specimen of unknown hardness tested, and radiation count recorded. Count compared with known sample to find Shore hardness of unknown.