• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제54권12호
• /
• pp.561-566
• /
• 2005

This paper describes electrical resistivity, dielectric strength, thermal conductivity, thermal stability and tensile strength of mica sheet impregnated with silicone rubber resin or silicone rubber resin containing alumina powder. The mica sheet impregnated with silicone rubber resin had higher electrical resistivity, dielectric strength and tensile strength than those of virgin mica sheet. Electrical resistivity of mica sheet impregnated with silicone rubber resin containing alumina increased with increasing the amount of alumina. However, dielectric strength and tensile strength of mica sheet impregnated with silicone rubber resin containing alumina decreased with increasing the amount of alumina. The mica sheet impregnated with silicone rubber resin had lower thermal conductivity than that of virgin mica sheet. However, thermal conductivity of mica sheet impregnated with silicone rubber resin conatining alumina increased with increasing the amount of alumina. In the case of thermal stability, thermal degradation of virgin mica sheet and impregnated mica sheet with silicone rubber resin did not occur up to $1100^{\circ}C$ and $400^{\circ}C$, respectively.

• 한국염색가공학회지
• /
• 제35권1호
• /
• pp.8-19
• /
• 2023

Silicone rubber is widely used in most industries due to diverse advantages like heat stability, UV stability, durability, chemical resistance, environment friendliness, inertness and so on. But there is limitation to expand applications due to relatively weak rubber strengths such as tensile strength and tear strength, especially in fabric coating applications. The purpose of this study is to find influence of coating agent on performances of rubber and coated fabrics and their correlation according to different crosslinking densities of silicone rubbers. Addition cure type of silicones were formulated using crosslinked MQ-type silicone resin consisting of M (R₃SiO_1/2) and Q (SiO_4/2) and linear polymers. Raw materials used were; 1) linear vinyl endblocked polymers and vinyl functional MQ resin as main polymers, 2) linear silicone hydride polymers as crosslinkers, 3) platinum catalyst and 4) inhibitor to control curing speed. Rubber specimens were prepared to check mechanical strength using universal testing machine (UTM). Crosslinking density was calculated using Flory-Rhener equation using solvent swelling method. Differential scanning calorimetry (DSC) and scanning electron microscope (SEM-EDS) were used to characterize rubbers. Consequently, it was found that physical properties of silicone rubbers and coated fabrics can be expected by crosslinking density of rubbers. Silicone rubber formulations that contain 20 ~ 30 wt% of vinyl MQ resin showed strongest balanced performances.

• 대한치과보철학회지
• /
• 제34권4호
• /
• pp.850-868
• /
• 1996

The accuracy and dimensional stability of impression materials are one of the most important factors for successful prosthodontic treatment. The purpose of this study was to evaluate the accuracy of several dental elastomeric impression materials used widely and clinically : Impregum-$F^{(R)},\;Permlastic^{(R)},\;Silascon^{(R)},\;Perfect^{(R)},\;Xantopren^{(R)}$. There have been many studies to evaluate the accuracy of impression materials. But it has not been decided yet, which method was most suitable for the evaluation of the accuracy. In this study, two resin teeth, #15 & 25, were prepared with rounded shoulder margin and 90 degree cavosurface angle. For the polysulfide rubber and polyether, the custom tray was made at least 24 hours prior to impression taking. For the silicone rubber materials, putty/wash impression technique was applied in taking impressions. Marginal openings of the castings on the master dies and prepared resin teeth were measured under stereomicroscope. The results were statistically analyzed and compared between tested impression materials. The results were as follows ; 1. In the overall accuracy of impression materials, polyether was the most accurate one, followed by polysulfide, additional silicone and condensation silicone. 2. On the first model pouring, condensation silicone had the largest discrepancies and there was significant difference compared to the other impression materials. 3. Polysulfide had the least discrepancies in the first model pouring, but showed larger discrepancies in the immediate second pouring than the first pouring. 4. On the immediate second pouring, the discrepancy of polyether was shown to be the smallest, while the largest one was additional silicone. 5. Polyether and polysulfide rubber using custom impression trays showed superior accuracy to silicone rubber, putty/wash impression technique.

• 대한치과보철학회지
• /
• 제29권2호
• /
• pp.59-66
• /
• 1991

This study was designed to investigate the marginal accuracy of resin temporary crown with different matrix in indirect technique. Matrices were made from irreversible hydrocolloid impression material, putty type of vinyl polysiloxane silicone rubber and vacuum formed plastic sheet. The marginal discrepancies of the temporary crowns were measured using a measuring microscope. The obtained results were as follows 1. The marginal accuracy temporary crown using vinyl polysiloxane silicone rubber or vacuum formed plastic form was better than that of the temporary crown using irreversible hydrocolloid impression material. 2. The marginal accuracies of the temporary crown using the irreversible hydrocolloid impression material and putty type of the vinyl polysiloxane silicone rubber obtained the best results at the distal measuring point. 3. The vacuum formed plastic form was recorded a more acceptable marginal accuracy at the distal and mesial measuring points.

• 대한기계학회논문집A
• /
• 제28권5호
• /
• pp.624-631
• /
• 2004

In this paper, new replication techniques fur a metal microcomponent having a real 3D shape were introduced. Helical gear was selected as one of a real 3D microcomponents for this study. The helical gear, which was made of photo-curable resin, was fabricated as a master pattern by microstereolithography technology. Then, a silicone rubber mold was fabricated from the master pattern. Lastly, a final bismuth alloy pattern was transferred from the silicone rubber mold by the microcasting process. In this paper, the replication technique is described in detail from the master pattern to the final pattern with some investigation on factors related to the technique.

• Elastomers and Composites
• /
• 제47권2호
• /
• pp.141-147
• /
• 2012

실리콘 수지는 소수성이 강한 고분자이기 때문에 수분을 흡수하는 기능이 전혀 없다. 하지만 고흡수성 수지(Super Absorbent Polymer)를 첨가제로 사용하면 기존의 실리콘보다 월등한 흡수성을 갖게 된다. 본 연구에서는 무정형 형태의 입자 크기가 다른 아크릴계 고흡수성 수지 3가지를 선택하여 배합비를 설정하고 2액형 타입의 의료용 실리콘 소재에 적용해서 수분을 흡수하는 기능을 갖는 새로운 실리콘 소재를 개발하였다. 고흡수성 수지의 첨가에 의한 실리콘 수지의 제조시 입자 사이즈와 함량을 달리하면서 인장, 인열, 압축, 경도에 대한 기계적 물성 변화를 알아보았으며, 시간에 따른 실리콘 수지의 흡수성을 측정하였다. 또한 전자 현미경을 통해 고흡수성 수지의 입자형태와 실리콘 수지와의 분포도를 관찰하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.495-496
• /
• 2008

This paper describes the influence of Ultra-violet irradiation on time to tracking resistance of epoxy insulating materials by use of the inclined plane test. And, the influence of surface degradation was evaluated through several method such as measurement of contact angle, surface roughness, using a scanning electron microscopy. As the 1000 hours of the surface degradation with UV-CON, the flashover time decreases at different rates depending on epoxy resin and silicone rubber specimen. As the duration of the surface degradation with UV-CON is prolonged, the contact angle of epoxy resin decreases at the rate of degradation time, while that of silicone rubber was not exchanged. It is assumed that this phenomenon is related to the decrease in hydrophobicity of the surface of the materials. Also, as to epoxy resin, the decrease of hydrophobicity due to surface degradation with UV-CON is greater than that resulting from surface degradation with WOM. The UV radiation produced chalking and crazing on the surface of the insulating materials specimen.

• Steel and Composite Structures
• /
• 제35권6호
• /
• pp.779-788
• /
• 2020

Multi-Walled Carbon nanotubes (MWCNT) coupled with Silicone Rubber (SR) can represent applicable strain sensors with accessible materials, which result in good stretchability and great sensitivity. Employing these materials and given the fact that the combination of these two has been addressed in few studies, this study is trying to represent a low-cost, durable and stretchable strain sensor that can perform excellently in a high number of repeated cycles. Great stability was observed during the cyclic test after 2000 cycles. Ultrahigh sensitivity (GF>1227) along with good extensibility (ε>120%) was observed while testing the sensor at different strain rates and the various number of cycles. Further investigation is dedicated to sensor performance in the detection of human body movements. Not only the sensor performance in detecting the small strains like the vibrations on the throat was tested, but also the larger strains as observed in extension/bending of the muscle joints like knee were monitored and recorded. Bearing in mind the applicability and low-cost features, this sensor may become promising in skin-mountable devices to detect the human body motions.

• 한국전기전자재료학회논문지
• /
• 제23권9호
• /
• pp.718-723
• /
• 2010

In this paper, the following results were obtained from the experiment in which electrification voltage of silicone rubber specimen for thermal bonding were measured under various time, temperature ($10{\sim}40^{\circ}C$), and humidity (30~90%) conditions and different amount of carbon additives (0~15 phr (per hundred resin)). Electrostatics electrification voltage decreased when carbon is up to 10 phr, and there was no electrification voltage in 15 phr condition. The electrostatics electrification voltage did not change over time. When the temperature was constant, electrostatics electrification voltage sharply dropped when the humidity was around 70%. That means, this condition might be appropriate for prevention of charging. The electrification voltage decreased as humidity and amount of carbon increased.

• 대한치과보철학회지
• /
• 제39권4호
• /
• pp.351-365
• /
• 2001

For accurate impression taking, accurate impression material, solid individual tray, and bond strength between impression materials and resin tray are important factors. The purpose of this study was to evaluate tensile bond strength of rubber impression materials to various tray resin materials. This study tested the time dependent tensile bond strength between commercial brands or poly ether, polysulfide, additional silicone impression materials and commercial brands of self curing tray resin. light activited tray resin when applying adhesive Resin specimens were made with 20mm in diameter, 2mm in thickness. 1 made total 360 specimens, 10 per each group and the tensile bond strength was measured by using the Instron($M100EC^{(R)}$, Mecmesin Co., England). The results were as follows ; Comparisons of various impression materials. 1. In case of Impregum $F^{(R)}$, the bond strength of tray resin was decreased in order of SR $Ivolen^{(R)}$, Ostron $100^{(R)}$ Instant tray $mix^{(R)}$, $Lightplast^{(R)}$. All groups excluding Ostron $100^{(R)}$, Instant tray $mix^{(R)}$ are significant difference (p<0.05). Drying time after applying adhesive, the tensile bond strength of tray resin was insignificantly decreased in order of 10 min drying time group. 1 min drying time group. 5 min drying time group. 2. In case of Permlastic $regular^{(R)}$ the bond strength of tray resin was insignificantly decreased in order of Ostron $100^{(R)}$. SR $Ivolen^{(R)}$, Instant tray $mix^{(R)}$ $Lightplast^{(R)}$. About drying time after applying adhesive, the tensile bond strength of tray resin was significantly decreased in order of 5 min drying time group, 10 min drying time group, 1 min drying time group(p<0.05). 3. In case of Exaflex $regular^{(R)}$. the bond strength of tray resin was decreased in order of $Lightplast^{(R)}$, SR $Ivolen^{(R)}$, Instant tray $mix^{(R)}$, Ostron $100^{(R)}$. $Lightplast^{(R)}$ was significant difference(p<0.05). About drying time after applying adhesive, the tensile bond strength of tray resin was decreased in order of 5 min drying time group, 10 min drying time group, 1 min drying time group(p<0.05). Especially 5 min ding time group was significant difference(p<0.05). According to the results of this study, we can see the greatest tensile bond strength when using Impregrm $F^{(R)}$ and Permlastic $regular^{(R)}$ with self curing tray resin, when using Exaflex $regular^{(R)}$ with light activated tray resin In my opinion, adhesive should be dried more than 5 min before impression taking to achieve the greatest tensile bond strength.