• Elastomers and Composites
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• 제52권4호
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• pp.257-265
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• 2017

In this work, CR (Chloroprene Rubber) was emulsified by phase-inversion emulsification with nonionic surfactants (NP-1025, LE-1017, and OP-1019) and an anionic surfactant (SDBS; sodium dodecylbenzenesulfonate), and its stabilization was investigated through a study of its adsorption characteristics, zeta potential, and flow behavior. As the amount of the mixed surfactant increased, the droplet size decreased, resulting in the increase of viscosity. In particular, a CR emulsion with a lower absorbance in the UV spectrum exhibited the highest zeta potential. The results of this experiment showed that the CR emulsion prepared using (LE-1017) and SDBS was the most stable. In this study, calcium hydroxide and aluminum hydroxide were added to enhance the mechanical properties of the CR emulsion, and the relationship between tensile strength, tear strength and surface free energy were investigated. The tensile and tear strengths of the CR emulsion incresed as the amount of calcium hydroxide and aluminum hydroxide increased. The highest tensile and tear strengths and surface free energy were observed for additions of 1.0% calcium hydroxide and 0.80% aluminum hydroxide, respectively. It was concluded that the interfacial bonding strength was improved by the even dispersion of calcium hydroxide and aluminum hydroxide in the CR emulsion.

• Composites Research
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• 제23권5호
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• pp.1-7
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• 2010

NBR과 강판의 접착특성을 향상시키기 위해 대기압 화염 플라즈마(APFP) 처리 장치가 사용되었다. 가장 우수한 접착특성을 나타내는 최적 조건을 찾기 위해 다양한 처리 조건(처리속도, 거리)에 따른 효과에 대한 실험적 연구를 하였다. 주어진 조건에서 버너 포트와 강판의 최적 거리는 40mm, 버너 포트의 최적 처리속도는 50m/min였다. APFP 처리 후 접착제를 두 번 도포한 강판의 접착강도는 접착제만 도포한 경우보다 20.5% 증가하였다. 본 연구를 통해서 대기압 화염 플라즈마 처리에 의한 강판의 표면개질이 고무와 강의 접착강도를 증가시키는 적절하면서도 응용이 가능한 방법임을 확인하였다.

• Elastomers and Composites
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• 제54권4호
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• pp.335-344
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• 2019

In this work, styrene butadiene rubber (SBR) and styrene butadiene styrene (SBS) were used to modify asphalt, resulting in SBR- and SBS-modified asphalt, respectively. The two modified asphalts were emulsified with a nonionic emulsifier (Span 60) and cationic emulsifiers (ID, DDA) and their phase stabilization was investigated via particle size, Zeta potential, and flow behavior analysis. With increasing amount of the mixed emulsifier, the particle size decreased, leading to an increase in viscosity. The shear thinning behaviors and Zeta potential values ranging from 35-65 mV were determined and remained considerably stable. In addition, the adhesion strength and compression strength of the SBR-and SBS-modified asphalt emulsion were evaluated via surface free energy examination. The remarkable adhesion and compression strengths were estimated when 5 phr ID and 6 phr DDA were added to the emulsified asphalt modified with SBR and SBS. Therefore ID and DDA, the two cationic surfactants, played significant roles in improving the dispersion and interfacial adhesion strength, resulting in the improved adhesion and compression strength of the emulsified asphalts modified with SBR and SBS.

• 한국임상수의학회지
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• 제24권2호
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• pp.201-207
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• 2007

The teat cup liner compounds with improved physical property were developed using tri-polymer blend of natural rubber(NR), ethylene propylene diene monomer rubber(EPDM) and butyl rubber, and the changes of the physical properties of compounds were measured under various conditions such as standard, thermal, alkaline detergent and acid solutions aging conditions. The hardness of the new teat cup liner compound 1 was 50 and that of the compound 2 was 51 under standard condition. The tensile strength and elongation of the new compound 1 were $154kgf/cm^2$ and 675% under the standard condition, respectively. Also, those of the new compound 2 were 180 kgf/cm and 634% under the same condition. Their hardness were increased about $2{\sim}6%$ and the tensile strength and elongation were decreased about 10% under the $25^{\circ}C$ water and detergent solutions. Even though the new teat cup liner compounds exhibited so much decreased tensile properties under the $105^{\circ}C$ thermal aged condition, they sustained more stable aged physical properties including tensile strength and elongation than those of imported teat cup liner materials. Consequently, the new teat cup liner compounds would give prolonged lift cycle if they are used as a teat cup liner product.

• Advances in concrete construction
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• 제11권5호
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• pp.409-417
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• 2021

The incorporation of non-biodegradable tyre waste in cement-based material has gained more interest towards sustainable construction these days. Crumb rubber (CR) from waste tyre is an alternative for sand replacement in low strength applications. Many researchers have studied CR cement-based materials produced by normal mixing (NM) method and reported a significant decrease in compressive strength due to CR. To compensate this strength loss, this research aims to study the innovative incorporation of CR in cement composite via the preplaced mixing (PM) method. In this investigation, cement composite was produced with NM and PM methods by replacing sand with 0%, 50%, and 100% CR by volume. The test results showed no significant difference in terms of densities of cement composite prepared with both mixing methods. However, cement composite prepared with PM method had lower strength reduction (about 10%) and lowered drying shrinkage (about 20%). In addition, the sound absorption coefficient and noise reduction coefficient of CR cement composite prepared by PM method were in similar range as those prepared with NM method. Overall, the results demonstrate that the PM method is promising, and the maximum replacement level of 50% is recommended for CR in the cement composite.

• Advances in concrete construction
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• 제10권6호
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• pp.537-546
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• 2020

Exterior walls in buildings are exposed to various forms of thermal loads, which depend on the positions of walls. Therefore, one of the efficient methods for improving the energy competence of buildings is improving the thermal properties of insulation plaster mortar. In this study, lightweight fine aggregate (LWFA) and micro rubber ash (MRA) from recycled tires were used as partial replacements for sand. The flow ability, unit weight, compressive strength, tensile strength, thermal conductivity (K-value), drying shrinkage and microstructure scan of lightweight rubberized mortar (LWRM) were investigated. Ten mixtures of LWRM were prepared as follows: traditional cement mortar (control mixture); three mixes with different percentages of LWFA (25%, 50% and 75%); three mixes with different percentages of MRA (2.5%, 5% and 7.5%); and three mixes consisting both types with determined ratios (25% LWFA+5% MRA, 50% LWFA+5% MRA and 75% LWFA+5% MRA). The flow ability of the mortars was 22±2 cm, and LWRM contained LWFA and MRA. The compressive and tensile strength decreased by approximately 64% and 57%, respectively, when 75% LWFA was used compared with those when the control mix was used. The compressive and tensile strength decreased when 5% MRA was used. By contrast, mixes with determined ratios of LWFA and MRA affected reduced unit weight, K-value and dry shrinkage.

• Geomechanics and Engineering
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• 제32권4호
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• pp.361-373
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• 2023

This study aimed to investigate the engineering properties and mechanical behaviors of polymer-fibers treated sand. Para rubber (PR), natural fiber (NF), and geosynthetic fiber (GF) were used to reinforce poorly graded sand. A series of unconfined compressive and splitting tensile strength tests were performed to analyze the engineering behaviors and strength enhancement mechanism. The experiment results indicated that the PR-fibers mixture could firmly enhance the strength properties of sand. The stress-strain characteristics and failure patterns have been changed due to the increase of PR and fibers content. The presence of PR and fibers strengthened the sand and enhanced the stiffness and ductility behavior of the mixture. The stiffness of reinforced sand reaches an optimum state when both NF and GF are 0.5%, while the optimum PR contents are 20% and 22.5% for the mixture with NF and GF, respectively. An addition of PR and fiber into sand contributed to increasing interlocking zone and bonding of PR-sand interfacial.

• Journal of the Korean Wood Science and Technology
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• 제26권1호
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• pp.70-75
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• 1998

In this paper, the relationships between volumetric mixing ratio of rubber chip and physical and mechanical properties of wood/rubber composite panel was examined in order to investigate the mixture characteristics of wood and rubber chip. Because of the specific gravity of rubber differed from wood chip, physical properties of wood/rubber composite panel was shown very different values by mixing rate of chip element. Specific gravity in air-dry of composite panel was increased rapidly as volumetric percent of rubber chip was increased. Moisture content of composite panel was decreased as volumetric percent of rubber chip element was increased. This results was considered that wood weight is light and porosity material for moisture absorption. Compressive strength and modulus of rupture in bending test were decreased as volumetric percent of rubber chip increased. By mixing ratio control of chip elements, various wood/rubber composite panel can be applicable to every interior materials such as subfloor, playground, and exterior materials such as road blocks for recreational facilities in garden and forest and city parks.

• Elastomers and Composites
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• 제31권2호
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• pp.111-121
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• 1996

The characteristic of silicone rubber can be seen from its resistance to both low and high temperature, whereas HNBR is resistant only in high temperature moderatly although it can be compounded to give good tensile properties, good oil resistance while silicone rubber severely lacks in these qualities. This study was initiated a balance of properties by blending HNBR and silicone rubber which is not considered for commercial blending; blends of HNBR with silicone rubber tend to show immiscible due to dissimilar nature of silicone and HNBR, the possibility of phase separation cannot be ruled out, in unfilled system after vulcanisation leading to premature failure. Attempt has been made to improve compatibility and minimise the layer seperation by the use of compatibilizer. Both filled and unfilled systems, in presence and absence of compatibilizer have been studied. Improvement in tensile properties of the blends or are observed as compared to the non-blended rubber. Different ratios of HNBR and silicone rubber are represented in this study. Blends of HNBR with silicone rubber were immiscible system. The tensile strength increased with filler loading.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.915-922
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• 2017

내열 및 내유성 고무복합체 특성연구(The study on the thermal and oil resistance rubber composite), 2016.[6] 연구에서는 고온($150^{\circ}C$, $175^{\circ}C$, $200^{\circ}C$) 조건의 고온촉진노화를 통하여 불소고무 복합체의 수명을 예측하였다. 일반적인 고무제품은 온도, 습도, 오존, 빛, 유제, 기계 및 전기적 응력 등의 특성저하 인자에 따라 다른 특성을 나타낼 가능성이 있으며, 이러한 문제를 해결하기 위하여 "내열 및 내유성 고무복합체 특성연구"[6] 연구에서 얻어진 고온촉진노화에 의한 수명 예측값과 저온촉진노화간의 인장강도 변화율 및 신장률 변화율 그리고 부피 변화율, 무게 변화율, 두께 변화율 및 열전도도를 비교 검토하였다. 검토 결과, 요구 한계수명은 모두 만족하였지만 고온촉진노화 결과와 저온촉진노화 결과 간 변화율에서 약간의 격차를 보였다. 이러한 변화율 격차가 일어나는 원인은 고온촉진노화에서는 노화 시 불소고무의 주사슬 분해로 인하여 인장강도, 신장률 감소 및 부피, 무게, 두께 증가가 일어나는데 비해 저온촉진노화에서는 $80^{\circ}C$에서 불소고무의 지속적 경화반응으로 인하여 인장강도, 신장률 및 부피, 무게, 두께 변화가 적게 나타났을 것으로 판단된다.