• Elastomers and Composites
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• v.53 no.4
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• pp.202-206
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• 2018

Five solution styrene butadiene rubber/neodymium butadiene rubber (SSBR/NdBR) composites were manufactured using different ratios of SSBR and NdBR. In this study, the composites were reinforced with NdBR and silica to confirm the physical properties of SSBR used for treads of automobile tires and the dispersibility with silica. The morphologies of the rubber composites were observed using field-emission scanning electron microscopy (FE-SEM). The crosslinking behaviors of the composites were tested using a rubber process analyzer (RPA), and the abrasion resistances were tested using a National Bureau of Standards (NBS) abrasion tester. The hardness values, tensile strengths, and cold resistances of the composites were also tested according to ASTM standards. Increased NdBR content yielded composites with excellent crosslinking properties, abrasion resistances, hardnesses, tensile strengths, and cold resistances. The crosslinking point increased due to the double bond in NdBR, thereby increasing the degree of crosslinking in the composites. The NdBR-reinforced composites exhibited excellent abrasion resistances, which is explained as follows. In SSBR, a breakage is permanent because a resonance structure between styrene and SSBR forms when the molecular backbone is broken during the abrasion process. However, NdBR forms an additional crosslink due to the breakdown of the molecular backbone and high reactivity of the radicals produced. In addition, the low glass transition temperature (Tg) of NdBR provided the rubber composites with excellent cold resistances.

• Composites Research
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• v.13 no.3
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• pp.30-37
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• 2000

The dynamic properties of short-fiber reinforced Chloroprene rubber have been studied as functions of interphase conditions and fiber content. The loss factor generally decreased with fiber content and showed different patterns according to interphase conditions. The better interphase condition showed the lower loss modulus, $E_2$. Also, the dynamic ratio decreased with fiber content and rapidly decreased in the case of double coatings, i.e., model C. Therefore, the short-fiber reinforced rubber could have the better isolation in frequency ratio($\sqrt{2}$ min.) compared to frequency ratio($\sqrt{2}$ max.). And we have investigate the possibility of applying short-fiber reinforced rubber to automotive engine mount.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.625-633
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• 2000

The mechanical and curing properties of short nylon66 fiber reinforced Chloroprene rubber have been investigated as functions of interphase conditions and fiber content. The tensile strength exhibits a dilution effect at a low fiber content in each interphase. It is found that the interphase conditions have an important affect on the dilution ratio and critical fiber content. Double coatings of bonding agent 402 and rubber solution become the best interphase model in this study. The yield strength, tensile modulus, tear strength and fracture toughness at rupture, Jr are significantly improved due to fiber concentration.

• Journal of Mechanical Science and Technology
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• v.15 no.1
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• pp.35-43
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• 2001

Both tensile and tear properties of short-fiber reinforced Chloroprene rubber have been studied as functions of the fiber aspect ratio and fiber content. Both properties increased when both the fiber aspect ratio and fiber content were increased. The fiber reinforced rubbers exhibited maximum values of these properties at a fiber aspect ratio of about 300. When the fiber aspect ratio exceeds 400, the mechanical properties decreased with the fiber content because of the non-uniform dispersion of fibers. The tensile modulus was compared with the prediction by the Halpin-Tsai equations for randomly oriented cases. A bonding agent was used in the fiber treating process. It was found that the ultimate tensile strength, torque, tearing energy and tensile modulus of the rubbers with treated fibers were much higher than those with untreated ones.

• Structural Engineering and Mechanics
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• v.61 no.1
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• pp.31-47
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• 2017

As a relatively new type of multi-layered rubber-based seismic isolators, fiber-reinforced elastomeric isolators (FREIs) are composed of several thin rubber layers reinforced with flexible fiber sheets. Limited analytical studies in literature have pointed out that "warping" (distortion) of reinforcing sheets has significant influence on buckling behavior of FREIs. However, none of these studies, to the best knowledge of authors, has investigated their warping behavior, thoroughly. This study aims to investigate, in detail, the warping behavior of strip-shaped FREIs by deriving advanced analytical solutions without utilizing the commonly used "pressure", incompressibility, inextensibility and the "linear axial displacement variation through the thickness" assumptions. Studies show that the warping behavior of FREIs mainly depends on the (i) aspect ratio (shape factor) of the interior elastomer layers, (ii) Poisson's ratio of the elastomer and (iii) extensibility of the fiber sheets. The basic assumptions of the "pressure" method as well as the commonly used incompressibility assumption are valid only for isolators with relatively large shape factors, strictly incompressible elastomeric material and nearly inextensible fiber reinforcement.

• Computers and Concrete
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• v.27 no.5
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• pp.417-435
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• 2021

The optimal distribution of steel fibers over different layers of concrete can be considered as an appropriate method in improving the structural performance and reducing the cost of fiber-reinforced concrete members. In addition, the use of waste tire rubber in concrete mixes, as one of the practical ways to address environmental problems, is highly significant. Thus, this study aimed to evaluate the flexural behavior of functionally graded steel fiber-reinforced concrete containing recycled tire crumb rubber, as a volume replacement of sand, after exposure to elevated temperatures. Little information is available in the literature regarding this subject. To achieve this goal, a set of 54 one-, two-, and three-layer concrete beam specimens with different fiber volume fractions (0, 0.25, 0.5, 1, and 1.25%), but the same overall fiber content, and different volume percentages of the waste tire rubber (0, 5, and 10%) were exposed to different temperatures (23, 300, and 600℃). Afterward, the parameters affecting the post-heating flexural performance of concrete, including flexural strength and stiffness, toughness, fracture energy, and load-deflection diagrams, along with the compressive strength and weight loss of concrete specimens, were evaluated. The results indicated that the flexural strength and stiffness of the three-layer concrete beams respectively increased by 10 and 7%, compared to the one-layer beam specimens with the same fiber content. However, the flexural performance of the two-layer beams was reduced relative to those with one layer and equal fiber content. Besides, the flexural strength, toughness, fracture energy, and stiffness were reduced by approximately 10% when a 10% of natural sand was replaced with tire rubber in the three-layer specimens compared to the corresponding beams without crumb rubber. Although the flexural properties of concrete specimens increased with increasing the temperature up to 300℃, these properties degraded significantly with elevating the temperature up to 600℃, leading to a sharp increase in the deflection at peak load.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.12 s.255
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• pp.1518-1525
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• 2006

Finite element analyses of structures made of the fiber reinforced composites require an adequate method to characterize the high anisotropic behavior induced by one or several layers of fiber cords with different spatial orientation embedded in a rubber matrix. This paper newly proposes a continuum based rebar element considering change of the orientation of the fiber during deformation of the composite. The mechanical behavior of the embedded fiber is modeled using two-node bar elements in order to consider the relative deformation and spatial orientation of the embedded fiber. For improvement of the analysis accuracy, the load-displacement curve of fiber is applied to the stiffness matrix of fiber. A finite element program is constructed based on the total Lagrangian formulation considering both geometric and material nonlinearity. Finite element analyses of the tensile test are carried out in order to evaluate the validity of the proposed method. Analysis results obtained with the proposed method provides realistic representation of the fiber reinforced rubber composite compared to results of other two models by the Halpin-Tsai equation and a rebar element in ABAQUS/Standard.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.10a
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• pp.99-106
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• 1991

Result of an experimental study on the manufacture, the mechanical properties and waterightness of pitch-based carbon fiber reinforced fly ash.cement composites are presented in this paper. The carbon fiber reinforced fly ash.cement composites using early strength cement, silica powder and a small amount of stylene butadiene rubber latex are prepared with carbon fiber, foaming agents and mixing conditions. As a result, the mechanical and plysical properties such as compresive, tensile and flectural strengths, watertightness and cement composites are improved by using a small amount of stylene butadiene rubber latex.

• Composites Research
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• v.19 no.6
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• pp.16-22
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• 2006

The puncture properties under various conditions were investigated for the optimum conditions to yield the best properties. Fiber aspect ratio(AR: length of fiber/diameter of fiber), interphase condition and fiber content were considered as variables which impact the puncture force and friction force. The puncture force of short-fiber reinforced rubber increases up to 3.4 times compared to the virgin material. The better interphase condition shows the higher puncture force at given fiber AR and fiber content. The friction force of the matrix and reinforced rubber with a fiber AR below 155 does not exist. The friction force of the reinforced rubber with the good interphase condition and high fiber AR is higher than puncture force of matrix. Overall, it was found that the interphase condition, fiber AR and fiber content have an important effect on the puncture properties.

• Composites Research
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• v.20 no.6
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• pp.28-33
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• 2007

The puncture properties of short-fiber reinforced rubber were investigated as functions of fiber aspect ratio(AR: length of fiber/diameter of fiber), fiber content, specimen size and testing velocity. The puncture stresses of the matrix and short-fiber reinforced rubber decreased with specimen size, and increased with testing velocity at same specimen size. As the fiber AR increased the puncture stress at given fiber content also increased. The problem of the specimen shape was investigated by the comparison of the tensile strength with puncture stress. The forces acting in the membrane wall of the matrix and the short-fiber reinforced rubber showed a similar data regardless of specimen size. And those increased with testing velocity at same specimen size. As the fiber AR increased the force acting in the wall at given fiber content also increased. Overall, it was found that the specimen size, testing velocity had an important effects on the puncture properties.