• Elastomers and Composites
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• v.50 no.1
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• pp.24-29
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• 2015

In this study, we investigated the effects of a crosslinking agent and a compatibilizer on the mechanical and rheological properties of waste PP and waste ground rubber tire (WGRT) composites. In order to simulate a commercial TPV, the component of waste PP and WGRT was fixed at 30 and 70 wt%, respectively. With the simple addition of SEBS-g-MA into the waste PP/WGRT composites, the tensile strength of the composite was decreased, whereas both the elongation at break and impact strength were significantly increased because of rubbery characteristics of SEBS-g-MA. In order to further improve the properties of the composites, the waste PP/WGRT/SEBS-g-MA composites was revulcanized with dicumyl peroxide (DCP). As expected, mechanical properties of the revulcanized composites was generally improved. Especially, with 15 and 1 phr of SEBS-g-MA and DCP, elongation at break was highest value of about 183% because of the recross-linking of WGRT without chain scission of the main chain. It was found that complex viscosity of the revulcanized composite increased which might verify further vulcanization of the WGRT.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.23-27
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• 2014

Purpose: The purpose of this study was to determine the dimensional stability of three rubber impression materials (polysulfide, polyvinylsiloxane, polyether) in an iodophor disinfectant. Materials and Methods: Seventy-two impressions were made with each material and divided into control, 10-minute, and 30-minute immersion groups using an iodophor as the disinfectant. A microscope was used to measure dimensional changes in the stone casts made from each group of impressions, and the percent change was analyzed using a two-way ANOVA (P = 0.05). Results: All dimensional changes after iodophor disinfection were small in 10 minute groups, however, showed significantly increased in 30 minute groups (P < 0.05). Conclusion: Clinically, it can be recommended to use iodophor disinfectant for rubber materials within 10 minute.

• Journal of Adhesion and Interface
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• v.2 no.4
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• pp.24-31
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• 2001

Polypropylenes(PP) with different melt index values were mixed with ethylene-propylene rubber(EPR) or ethylene-propylene diene monomer rubber(EPDM) and an ethylene copolymer containing carboxylic acid group in a twin screw extruder. Then test specimens were prepared from the pellets of the blends with an injection molding machine. The mechanical properties and morphology of fractured surfaces were measured. Relative peak intensities of carboxylic acid group on the specimen surface were measured with an attennuated total reflection infrared spectrometer (ATR-IR) and compared with each other. The blend specimens were found to have the gradient morphology of rubber domains in PP matrix in the core region and PP skin layer. The blends containing PP of higher melt index showed greater content of ethylene copolymer containing carboxylic acid on the surface when the relative peak intensities of ATR-IR for carboxylic acid were compared. As the melt index values were increased, the decrease tendency in mechanical propeties such as tensile strength and impact strength was more significant for PP/EPR blends than PP/EPDM blends.

• Composites Research
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• v.37 no.3
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• pp.186-189
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• 2024

This study compared and evaluated the mechanical properties of carbon fiber reinforced thermoplastic polymer (CFRTP) mixed with nanofillers. After mixing various nanofillers such as Multi-wall carbon nanotube (MWCNT), Silicon oxide, Core shell rubber, and Aramid nanofiber with Polyamide 6 (PA6) resin, this is used as a matrix to create a carbon fiber reinforced composite material (CFRP) was manufactured and its physical properties were measured. Depending on the type and mixing ratio of nanofiller, tensile strength, inter-laminar shear strength (ILSS), and Izod impact strength were measured. In terms of tensile strength and impact strength, the highest values were obtained when mixing core shell rubber, however the ILSS was optimal when mixing less than 1 wt.% of silicon oxide.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.939-952
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• 1998

Rubber dampers are widely used to damp out vibrations generated in many mechanical elements because of the excellent damping characteristics of rubber. The damping characteristics of rubber is much dependent on temperature and frequency, which, in some cases, limit the effectiveness of rubber dampers. In this study, in order to increase the damping properties and axial and cross stiffnesses of rubber vibration dampers which are used in recording and regenerating devices, solid cores were inserted with interference tolerance in the rubber dampers. The damping characteristics of the rubber dampers with cores were investigated by experimentally and numerically using finite element method with respect to the interference tolerance, the core roughness, the materials of the core and the environmental temperature. From the experimental and theoretical investigations, it was found that the core in the rubber increased both the damping and stiffness of the damper. Also, it was found that the damping and stiffness of the rubber damper were much dependent on the temperature and frequency. Using the results of the experimental and theoretical investigations, the optimum design method for the cored rubber damper for recording and regenerating devices was developed.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.5-12
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• 2014

Weatherstrip coatings of urethane and silicon type which are fit to EPDM and thermoplastic materials are used in sealing systems for automotive applications for noise reduction and high slip characteristics for external applications, respectively. Polyurethane binder was successfully synthesized from poly(butyladiphate)diol (PBAD), poly(tetramethylene)glycol (PTMG) and isocyanate as starting materials. Then, polyurethane coating agents were prepared by using various additives. To investigate effects of segment types on the abrasion resistance of polyurethane coating agents, thin films based on polyurethane coating materials were fabricated. With increasing the amount of hard segment in the coating agent, abrasion resistance, modulus and tensile strength of the coating films were improved, but the elongation of the coating films was decreased.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.704-709
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• 2001

Experimental methods to determine non-linear properties of rubber materials for finite element analysis is discussed. In simple tension tests, dumbbell specimens are generally used to obtain states of pure tension strain. It is shown that the strip specimens of which length is over 10 times of the width can be also used. In simple compression tests, the effect of the friction between the test specimen and the platens is investigated. the new test method with the tapered platen is proposed in order to overcome the effect of friction and it is verified by experimental and finite element analysis results. In pure shear tests, it is shown that the width of the specimen must be at least 10 times of the height. The mechanical conditioning is suggested to stabilize the properties of the rubber materials. Also, engine mount for automotive is analyzed and experimented for each cases.

• Journal of Adhesion and Interface
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• v.7 no.2
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• pp.12-18
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• 2006

Recently, as industries and technologies are increased, superior adhesives having more and more developed functions and properties have been demanded. In this article, to use the merits and viscoelastic properties of poly(ethylene/butylene) rubber resin and to supplement the demerits, semi-structure pressure sensitive adhesives (PSAs) are developed. Aslo, it can be said environmentally friendly PSAs because of not use the organic solvent and not emit volatile organic compounds (VOCs).

• Korean Journal of Materials Research
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• v.33 no.8
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• pp.323-329
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• 2023

There are many types of foam molding methods. The most commonly used methods are the pressure foaming method, in which foam resin is mixed with a foaming agent at high temperature and high pressure, and the normal pressure foaming method, which foams at high temperature without pressure. The polymer resins used for foaming have different viscosities. For foaming under normal pressure, they need to be designed and analyzed for optimal foaming conditions, to obtain resins with low melt-viscosity or a narrow optimal viscosity range. This study investigated how changes in viscosity, molding temperature, and cross-link foaming conditions affected the characteristics of the molded foam, prepared by blending rubber polymer with biodegradable resin. The morphologies of cross sections and the cell structures of the normal pressure foam were investigated by SEM analysis. Properties were also studied according to cross-link/foaming conditions and torque. Also, the correlation between foaming characteristics was studied by analyzing tensile strength and elongation, which are mechanical properties of foaming composites.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.17-23
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• 2006

Rubber materials have the nonlinear, large deformation and viscoelastic behavior. W.D. Kim et al. studied these characteristics through the static, fatigue, dynamic, aging and viscoelastic test. This paper discussed that the properties of engine mounting rubber, such as static stiffness, fatigue life and damping factor, are predicted based on CAE by using material properties acquired by the report of Kim et al. In result, the static stiffness of engine mounting rubber is predicted approximately in comparison with test value. Also, it was confirmed that the relationship of fatigue life and Green-Lagrange strain in specimen was the valid tool to predict the fatigue life of engine mounting rubber. From the results of transient viscoelastic analysis the damping factor changed rapidly at the range less than 8hz.