• Journal of Adhesion and Interface
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• v.12 no.1
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• pp.26-33
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• 2011

Phosphoric acid treatments were conducted to improve the adhesion property of polyketone film to rubber. The effects of phosphoric acid treatments were characterized by using a contact angle analyzer and a XPS (X-ray photoelectron spectroscopy). Morphological changes were observed by using a scanning electron microscope (SEM) and an atomic force microscope (AFM) as the acid treatment condition varied in concentration and time. The contact angle was found to significantly decrease with the acid treatment. According to the XPS, increased wettability was attributed to the inclusion of oxygen containing groups such as hydroxyl, carbonyl and carboxyl by acid treatments. Cracks and pores were produced on the polyketone film surface and thus, roughness increased with the acid treatment. Interfacial adhesion strength between polyketone and natural rubber was largely improved by acid treatment due to the increased wettability and roughness of the polyketone surface. However, the higher level of acid treatment caused the degradation of the polyketone surface, and thus, its interfacial adhesion consequently decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.1-5
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• 2003

This paper presented the effects of accumulation of surface charges on hydrophobicity level and the surface states of silicone polymer used for outdoor insulator treated by ultraviolet irradiation and corona discharge through measuring surface voltage decay of a corona-charged specimen were investigated. The surface resistivity by the method of the surface potential decay was compared with the value by the three electrodes methods. From this study, it was found that the accumulation of surface charges above a critical surface voltage on silicone insulating materials could lead to the temporary loss of surface hydrophobicity. In addtion, uv stress lead to a longer decay time of surface charges. We could conclude that the effects of surface charges on hydrophocity level and the changes of surface state by various artificial treatments were understood through a trend of surface potential decay.

• Journal of the Korean Chemical Society
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• v.45 no.4
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• pp.341-350
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• 2001

Aluminum Hydroxide was employed as a thermal retardent and flame retardent for Chloropolyethylene (CPE) rubbery materials which is the construction material of automotive oil cooler hose. and then cure characteristics, physical properties, thermal resistance and flame retardation of compounded rubber were investigated, and optimum mixing conditions of rubber and flame retarding agent were deduced from the experimental results. CPE rubber material which has excellent properties of chemical corrosion resistance and cold resistance and inexpensive in price was used to prepare rubber specimen. The by-product of ething, produced from the process of surface treatment of aluminum was processed to aluminum hydroxide via crushing and purification, which is characterized by XRD, PSA, SEM and ICP-AES techniques in terms of phase, size, distribution, morphology and components of particles and then mixed to CPE rubber materials in the range of 0~80 phr. Hardness, tensile strength, elongation and thermal properties of compounded rubber specimens were tested. The optimum mixing ratio of rubber to additives to give maximum effect on thermal resistance and flame retardation, within the range of tolerable specification for rubber materials, was determined to be 40 phr. The flame retardation of CPE rubber materials was found to be increased by 5 times at this mixing ratio.

• Elastomers and Composites
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• v.45 no.2
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• pp.112-121
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• 2010

In this study, styrene butadiene rubber(SBR)/organoclay nanocomposites were manufactured using the latex method with 3-aminopropyltriethoxysilane(APTES) as a modifier. The X-ray diffraction(XRD), transmission electron microscopy(TEM) images, Fourier transform infrared(FTIR) spectroscopy, swelling ratio and mechanical properties were measured in order to study the interaction between filler and rubber according to the mixing temperature in the internal mixer. In the case of SBR/APTES-MMT compounds, the dispersion of the silicates within the rubber matrix was enhanced, and thereby, the mechanical properties were improved. The characteristic bands of Si-O-C in APTES disappeared after hydrolysis reaction in the MMT-suspension solution and the peak of hydroxyl group was increased. Therefore the formation of chemical bonds between the hydroxyl group generated from APTES on the silicate surface and the ethoxy group of bis(triethoxysilylpropyl) tetrasulfide(TESPT) was possible. Consequently, the 300% modulus of SBR/APTES-MMT compounds was further improved in the case of using TESPT as a coupling agent. However, the silanization reaction between APTES and TESPT was not affected significantly according to the increase of mixing temperature in the internal mixer.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.525-530
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• 2005

Maxillary median diastema is the term used when there is spacing between maxillary central incisors. The space between maxillary central incisors are often observed during ugly duckling stage. In most of the cases, as maxillary permanent canines erupt, it gradually disappears. Maxillary median diastema needs to be treated when there is up to 2mm of space between the incisors even after eruption of permanent canines or when there is 3mm of space, at least, before the eruption of the canines. Particulary, for the latter case, orthodontic treatment is recommended because not only the esthetic point of view but also to regain the eruption space for maxillary lateral incisors and canines. The appliance used for orthodontic treatment are removable appliances, using finger spring and etc, and fixed appliances, using rubber elastics and coil spring. If rubber band alone was used to treat median diastema without any other appliance such as band, tube or bracket, it will gradually move downward along the root surface. Then it will destroy the peridontal ligament and causes tooth mobility, extrusion, and avulsion. This report presents cases of damaged tooth due to improper use of rubber band when treating maxillary median diastema.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.88-92
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• 2006

Physicochemical, texture, and sensory properties of Jeung-pyun prepared with different concentrations of Monascus rubber DSJ-20 (Red yeast rice) were determined. Acidities and pH values of 3-5% M. rubber DSJ-20-treated groups were similar to those of control group. Degree of surface color increased in proportion to M. rubber DSJ-20 concentration. Hardness, gumminess, and chewiness of 1-2% M. rubber DSJ-20-treated groups were higher than those of control. Network structures of 3-15% M. rubber DSJ-20-treated groups were well-formed, similar to that of control. Strong bitter taste and flavor of Monascus were detected in 5-15% M. rubber DSJ-20-treated groups through sensory evaluation. These results suggest is 3% M. rubber DSJ-20 is desirable leavening concentration for making Jeung-pyun.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.2
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• pp.146-156
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• 2001

The purpose of this study was twofold. One was to evaluate the wettability of 4 elastomeric impression materials on tooth and different kinds of filling materials. The other was to identify the effect of topical surfactants sprayed on the surface of each impression. The elastomeric impression mate rials used in this experimental study were one polyether(Impregum F) and three polyvinyl siloxanes(Provil novo, Zerosil, Imprint). The abutments were prepared for 3/4 crown or onlay on the extracted human first molar. The filling materials used in this study for the duplication of prepared abutment were composite resin, amalgam, and casting metal. Impression was taken by manufacturer's recommendations and the number of voids on the impression surface was counted. The topical surfactants were Spannex $II^{(R)}$ and $Cohere^{(R)}$. The wettability was evaluated by comparing the number of voids between non-treated group and treated groups. The results were as follows : 1. $Zerosil^{(R)}$ showed the least number of voids on the impression surface. The number of voids increased in order of Provil $novo^{(R)}$, Impregum $F^{(R)}$, and $Imprint^{(R)}$. 2. Impregum $F^{(R)}$ and $Zerosil^{(R)}$ showed the least number of voids on the surface of dental stone master cast. The number is inclosed in order of Provil $novo^{(R)}$ and Imprint 3. When abutment material is tooth, the number of voids on the surface of master cast was smallest compared with that of other abutment materials. The number of voids increased in order of casting metal, amalgam and composite resin 4. The number of voids on the surface of the dental stone master cast was smallest when Spannex $II^{(R)}$ was used, followed by $Cohere^{(R)}$ treated group and non-treated group. These results suggest that the difference in wettability caused by the types of rubber base impression materials as well as abutment materials can affect the number of voids. And the use of topical surfactant for rubber base impression materials can improve the wettability of the materials and enhance the accurate master cast which has fewer surface voids.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.16-17
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• 2007

개발한 3 D 대기압 플라즈마 헤드와 그 특성 및 장단점 및 그에 의한 표면 개질 특성을 나타낸다. 플라즈마 처리 높이가 75 mm 이상의 시편도 처리할 수 있는 3 D 대기압 플라즈마 헤드를 개발하였으며, 그에 의한 신발 재료 EVA, PU, Rubber의 표면 개질 특성을 평가하였다. 또한 반도체 및 FPD 처리용 대기압 플라즈마도 개발하였다.

• Clean Technology
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• v.27 no.1
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• pp.24-32
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• 2021

Unburned carbon (UC) was successfully separated from fly ash by up to 85.8% in weight via froth flotation using soybean oil as a collector. An 18 wt% yield of microceramics (CM) could be achieved by employing a hydro cyclone separator located immediately after the flotation equipment. UC and CM were tested as alternatives to weight-adding material and polymer (especially polypropylene in this study) filler, respectively. Large particles of UC were broken down into smaller ones via ball milling to have an average particle diameter of 10.2 ㎛. When crushed UC was used as an alternative to clay as a rubber weight-adding material, a somewhat lower tensile strength and elongation rate than the allowed values were unfortunately obtained. In order to satisfy the standard limits, further treatment of UC is required to enhance surface energy for more intimate bonding with rubber. CM was observed in spherical forms with an average diameter of 5 ㎛. The surface of the CM particles was modified with phenol, polyol, stearic acid, and oleic acid so that the surface modified CM could be used as a polypropylene-filling agent. The flowability was good, but due to the lack of coupling forces with polypropylene, successful impact strength and flexural strength could not be obtained. However, when mixing the surface-modified CM with 1% silane by weight, a drastic increase in both the impact strength and flexural strength were obtained.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3762-3766
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• 2013

This article examines the modification of surface properties of ultrahigh-molecular-weight polyethylene (UHMWPE) with nanoscale ceramic particles to fabricate an improved composite with butadiene-nitrile rubber (BNR). Adhesion force data showed that ceramic zeolite particles on the surface of UHMWPE modulated the surface state of the polymer and increased its compatibility with BNR. Atomic force microscopy phase images showed that UHMWPE made up the microphase around the zeolite particles and formed the evolving layer with a complex interface. The complex interface resulted in improvements in the mechanical properties of the composite, especially its low-temperature resistance coefficients, thereby improving its performance in low-temperature applications.