Tire and, South Korea
Tire and, South Korea

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Kim K.-J.,Dong Ah Tire and Rubber Co.
Asian Journal of Chemistry | Year: 2013

The degree of silica dispersion in a rubber matrix is an important issue in the rubber industry because silica agglomerates in rubber compounds are difficult to disperse compared to carbon black due to the polar characteristics of the silica surface. Considerable effort has been made to improve the degree of silica dispersion, such as the use of bifunctional organosilane, intermesh rotor type mixer, milling technique, etc. Wolff and his coworkers introduced the in-rubber filler structure (aF) for quantitative measurements of the filler structure. This paper reviews his research on the in-rubber structure of carbon black and silica and reports our recent results on silane-treated silica.


Kim S.M.,Dong Ah Tire and Rubber Co. | Nam C.S.,Dong Ah Tire and Rubber Co. | Kim K.J.,Dong Ah Tire and Rubber Co.
Applied Chemistry for Engineering | Year: 2011

Various types of accelerators, thiuram (TMTD), thiazole (MBTS), and sulfenamide (CBS) are added into a silica filled natural rubber (NR) compound. Their effects on vulcanization properties are also investigated. TMTD shows a fast vulcanization rate and a higer maximum torque (T max), as well as excellent mechanical properties (hardness, 300% modulus, tensile strength, elongation). MBTS shows a moderate vulcanization rate, a lower T max, and mechanical properties. Finally, CBS shows a slow vulcanization rate but excellent mechanical properties. The same vulcanization trend can be found in carbon black filled NR compounds.


Oh J.S.,Hyundai Motor Company | Lee S.-H.,Hyundai Motor Company | Bumm S.,University of Akron | Kim K.-J.,Inha University | Kim K.-J.,DongAh Tire and Rubber Co.
Polymer (Korea) | Year: 2013

The effects of nano size kenaf cellulose fiber on mechanical property of polypropylene (PP) composite were investigated. The addition of nano-kenaf in place of natural kenaf showed higher tensile strength, flexural strength, impact strength, and heat deflection temperature compared to the natural kenaf filled PP composite, while it shows lower melt flow index, elongation%, and flexural modulus. These seemed to be due to the increased surface area of nano-kenaf fiber contacting PP matrix and reduced impurities such as volatile extractives on the fiber surface.


Kim S.M.,Dong Ah Tire and Rubber Co. | Kim K.J.,Dong Ah Tire and Rubber Co.
Polymer (Korea) | Year: 2014

Due to the polar characteristics of silica compared to carbon black, the degree of silica dispersion, which affects the mechanical properties of rubber compounds, is an important issue. Wolff first introduced the in-rubber structure of particles (αF) to express the structure development in the compounds; however, with the introduction of bifunctional silanes, his theory could not explain the 3-dimensional network structure of the compounds. Later his theory was expanded to express the composite interaction parameter (in-rubber structure of the compound) (αc), which included Wolff's filler-filler interaction parameter (αF), however, there was no reported experimental result proving the theory. This research first experimentally expressed the in-rubber structure of the compound αc (= αF + αFP(filler-siIane-rubber interaction parameter) + αP (rubber-rubber interaction parameter)) upon mono- and bifunctional silane treated silica filled natural rubber (NR) compounds. Using different structure silanes, i.e. RTES, OTES, TESPD, and TESPT, the αc value of each compound was measured and calculated. The αc value of TESPT treated silica filled compound was 1.64, which composed of αF (0.99), αFP (0.31), and αP (0.34).


Kim S.M.,Dong Ah Tire and Rubber Co. | Kim K.J.,Dong Ah Tire and Rubber Co.
Polymer (Korea) | Year: 2012

A thiazole type accelerator MBT (2-mercapto benzothiazole) was added into silica filled natural rubber (NR) compound with various concentrations (0, 1, 2, 3, 4 phr). The effects of MBT on the cure rate, mechanical property, degree of rubber-fill er interaction (a F), crosslinking density, and viscoelastic property (tan5) were investigated. As accelerator concentration increased, the t s2 and t 90 decreased and the crosslinking density and modulus at 300% elongation increased. The tensile strength and elongation increased up to 3 phr and no further increased at 4 phr. The tan S value measured at room temperature was higher than that of the 70 °C. The αf value was not affected by the addition of MBT. The mechanisms for the vulcanization rate were reviewed.


Kim S.-M.,Dongah Tire and Rubber Co. | Kim K.-J.,Dongah Tire and Rubber Co.
Polymer (Korea) | Year: 2013

Thiuram (DPTT, TMTD), thiazole (MBT, MBTS), sulfenamide (CBS, NOBS), and zinc containing thiuram (dithiocarbamate) (ZDBC) type accelerators were added into silica and carbon black filled natural rubber (NR) compounds. Their effects on vulcanization time and rate were compared. The vulcanization rate of thiuram type accelerator added compounds showed the fastest rate, followed by thiazole and sulfenamide types. Silica filled natural rubber (NR) compounds showed a slower vulcanization time (tS2, t10, t90) and lower cure rate index (CRI) than carbon black filled ones upon each accelerator.


Kim S.M.,Dong Ah Tire and Rubber Co. | Kim K.J.,Dong Ah Tire and Rubber Co.
Polymer (Korea) | Year: 2012

The effects of mixing geometry (intermeshing vs. tangential rotor) for the dispersion and distribution of silica agglomerates in SBR/BR compound were investigated. Silica dispersion and distribution were found to be better with the intermeshing rotor compared to the tangential rotor. It was concluded that the intermeshing rotor compared to the tangential rotor delivered a higher shear stress due to interlocked rotor geometry to silica agglomerates leading to better dispersity and distribution of silica in the agglomerates.


Kim K.-J.,University of Akron | Kim K.-J.,Dong Ah Tire and Rubber Co.
Journal of Applied Polymer Science | Year: 2012

Organo bifunctional silane (TESPD) is added into silica containing NBR/PVC blend and its effects are investigated with respect to the vulcanization property, the processability, and the physical property. The addition of the TESPD into silica filled NBR/PVC compound increases the degree of crosslinking by formation of a strong three-dimensional network structure between silica surface and rubber matrix via coupling reaction, which results in improved mechanical properties. It also improves the processability of the compound compared to the Control compound. © 2011 Wiley Periodicals, Inc.


Kim S.M.,Dong Ah Tire and Rubber Co. | Kim K.-J.,Dong Ah Tire and Rubber Co.
Polymer (Korea) | Year: 2014

Zinc ion containing thiuram type accelerator zinc di-butyldithiocarbamate (ZDBC) was compared to other thiuram type accelerators (tetramethylthiuram disulfide (TMTD) and dipentamethylenethiuram tetrasulfide (DPTT)) in silica filled natural rubber (NR) compound upon vulcanization and mechanical properties (modulus, tensile strength, and elongation %). ZDBC added compound showed the fastest cure time (t10) and the highest reinforcement index (R.I.) among them and showed a marching behavior. The mechanism was reviewed and a new mechanism was proposed.


Kim S.M.,Dong Ah Tire and Rubber Co. | Kim K.-J.,Dong Ah Tire and Rubber Co.
Polymer (Korea) | Year: 2015

The effects of silica-silane in CIIR vibration isolation compound were investigated regarding mechanical and dynamic properties. Addition of silica-silane in the compound resulted in higher tear resistance strength and elongation at break than the control, which was increased by 13% and 14%, respectively. Other values such as tensile strength and hardness did not show significant changes. Viscoelastic property results supported that the improvement of tear resistance strength and elongation at break resulted from the formation of 3-dimensional network structure between silica and CIIR. The mechanism of the tear resistance strength and elongation at break improvement was discussed.

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