• Title/Summary/Keyword: silicone

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Relationship between Weather-Resistance and Mixing Ratio of Mill-Base and Let-Down Silicone/Acrylic Resins (안료분산용 및 희석용 실리콘/아크릴수지의 배합비와 내후성과의 상관관계)

  • Jo Hye-Jin;Shim Il-Woo;Hahm Hyun-Sik;Park Hong-Soo
    • Polymer(Korea)
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    • v.30 no.4
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    • pp.350-356
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    • 2006
  • In order to investigate the effect of the composition of weather-resistant coatings on physical properties, three different weather-resistant coatings were prepared by varying the ratio of a mill-base silicone/acrylic resin and let-down silicone/acrylic resin in weight ratios of 2 : 8, 3 : 7, and 4 : 6. The physical properties and weather-resistance of the prepared coatings were tested. It was found that the thermal stability, salt spray exposure, and weather-resistance were improved with increasing the amount of silicone. The optimum mixing ratio of mill-base silicone/acrylic resin to the let-down silicone/acrylic resin was 2 : 8. The coating containing silicone component of 30 wt% was found to be suitable as high weather-resistant coatings.

Regulation of Transforming Growth Factor ${\beta}1$, Platelet-Derived Growth Factor, and Basic Fibroblast Growth Factor by Silicone Gel Sheeting in Early-Stage Scarring

  • Choi, Jaehoon;Lee, Eun Hee;Park, Sang Woo;Chang, Hak
    • Archives of Plastic Surgery
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    • v.42 no.1
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    • pp.20-27
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    • 2015
  • Background Hypertrophic scars and keloids are associated with abnormal levels of growth factors. Silicone gel sheets are effective in treating and preventing hypertrophic scars and keloids. There has been no report on the change in growth factors in the scar tissue following the use of silicone gel sheeting for scar prevention. A prospective controlled trial was performed to evaluate whether growth factors are altered by the application of a silicone gel sheet on a fresh surgical scar. Methods Four of seven enrolled patients completed the study. Transforming growth factor (TGF)-${\beta}1$, platelet-derived growth factor (PDGF), and basic fibroblast growth factor (bFGF) were investigated immunohistochemically in biopsies taken from five scars at 4 months following surgery. Results In both the epidermis and the dermis, the expression of TGF-${\beta}1$ (P=0.042 and P=0.042) and PDGF (P=0.043 and P=0.042) was significantly lower in the case of silicone gel sheet-treated scars than in the case of untreated scars. The expression of bFGF in the dermis was significantly higher in the case of silicone gel sheet-treated scars than in the case of untreated scars (P=0.042), but in the epidermis, the expression of bFGF showed no significant difference between the groups (P=0.655). Conclusions The levels of TGF-${\beta}1$, PDGF, and bFGF are altered by the silicone gel sheet treatment, which might be one of the mechanisms of action in scar prevention.

The Clinical Analysis of Two Layer Vasovasostomy Using Silicone Tube (실리콘 관을 이용한 이층 정관정관 문합술)

  • Choi, Eui Chul;Choi, Hwan Jun;Yun, Jong Hyun;Kim, Yong Bae
    • Archives of Plastic Surgery
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    • v.36 no.2
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    • pp.183-187
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    • 2009
  • Purpose: Because of the volume of elective sterilizations performed in the world during the past decade, the vasectomy was a popular method for male sterilization in Korea and this, in turn, had been followed by an increase in the number of patient requiring vasectomy reversal with the high rate of subsequent divorce and remarriage. Recently, many authors have reported high success rates of vasovasostomy using microsurgical techniques and we performed modified two layer vasovasostomy with intravasal silicone tube to increase postoperative patency and pregnacy rate. Methods: Microscopic vasovasostomy was performed in 9 patients and their average age was $35.78{\pm}1.36years$(from 28 years to 44 years) from June 2006 to June 2008 at our department using modified two layer vasovasostomy with silicone tube insertion. Standard Guibor silicone tube, consisting of two 17.7 cm, 0.064 cm diameter, malleable, stainless steel probes connected by 29 cm of silicone tubing wedged onto disposable probes, were used in all cases. Results: Success rates were 88.8 % for patency and pregnancy 44.4 % for pregnancy in modified two layer vasovasostomy with silicone tube insertion. The patency rates were higher in cases of long postoperative day and in cases of short duration of vasectomy and vasovasostomy. Conclusion: We used a modified method to correspond the patency and pregnancy rate in microscopical modified two layer vasovasostomy using the intravasal silicone tube permanently. This method brings normal patency in microsurgical vasovasostomy because the silicone tube prevent obstruction of anastomosed site of the vas permanently.

Effects of Hydroxy Silicone Oil on Insulation Properties of Silicone Rubber (Hydroxy Silicone Oil이 실리콘 고무의 절연특성에 마치는 영향)

  • Kang, Dong-Pil;Park, Hoy-Yul;Ahn, Myeong-Sang;Kim, Dae-Whan;Lee, Hoo-Bum;Oh, Se-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.11a
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    • pp.51-54
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    • 2002
  • 폴리머 애자용 Shed 재료의 전기방전에 대한 열화내성과 표면발수성은 제품의 장기성능에 있어서 가장 중요한 물성들이다. 그러나 무기보강재의 첨가량이 많아 무결점 성형성을 만족하도록 하기 위해서 Process Oil의 사용이 불가피한데 사용하는 오일의 종류와 양에 따라 옥외절연물의 장기성능에 영향을 주는 표면발수성이나 방전내성은 크게 차이가 나는 것으로 밝혀져 있다. 본 논문에서는 화학적 구조와 점도가 다른 몇 종의 hydroxy silicone oil(HS 오일)을 혼련 (kneading) 하는 과정에 첨가하여 이들 오일의 종류와 양이 고무의 기본적인 물성, 발수성, 방전열화내성, 내트래킹성 등에 어떻게 영향을 주는가를 조사하였다. 코로나 처리시간에 따라서 접촉각의 저하정도와 코로나 처리 후 경과시간에 따른 발수성의 회복특성을 조사하였다. HS 오일의 접도에 따라 초기발수성, 발수성 회복특성의 차이가 많았다. 점도가 낮을수록 초기 발수성 저하는 크며 회복속도는 빠른 반면 점도가 높을수록 초기 발수성 저하는 작은 반변은 발수성 회복속도는 다소 느리게 나타났다 내트래킹성 결과는 점도가 높을수록 우수한 특성을 보였다. 결론적으로 폴리머 애자용 실리콘고무의 컴파운딩에서 실리콘오일의 선택은 성형작업성, 발수성회복특성, 열화내성 외에 가격 등을 고려하여 최적화가 필요하다.

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Preparation of Polysiloxane Composite Films with Microphase-Separated Silicone Oiol by Photocrosslinking (광가교 반응에 의한 미세 상 분리된 실리콘 오일을 함유하는 폴리실록산 복합체 필름의 제조)

  • 이정분;김정수;강영구;김동욱;이창진
    • Polymer(Korea)
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    • v.27 no.1
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    • pp.3-8
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    • 2003
  • Polysiloxanes with methacrylate groups at both terminals were synthesized by a hydrosilylation reaction between allyl methacrylate and hydride-terminated polysiloxanes. The polysiloxane methacrylates with high molecular weights could be prepared through the reaction of polysiloxane methacrylates and octamethylcyclotetrasiloxane with an acid catalyst. The structures of the prepared polysiloxane methacrylates were verified by $^1$H- and $^{29}Si-NMR.$ The polysiloxane methacrylates were freely miscible with silicone oils. Polysiloxane films with microphase-separated liquid silicone oil were prepared by photo-crosslinking the mixture of polysiloxane methacrylates and silicone oil. Scanning electron microscopy (SEM) of the films showed that the size of silicone oil droplets became smaller with a lower loading of silicone oil, lower molecular weight of polysiloxane methacrylate, and lower molecular weight of silicone oil.

Effectiveness of Endoscopic Dilatation & Silicone Stent Insertion for Tracheobronchial stenoses : Preliminary study (기관-기관지 협착에서 내시경적 확장술 및 실리콘 스텐트의 유용성 : 예비보고)

  • Lee, Kyong-Soo;Park, Dong-Wook;Kim, Kyu-Hun;Kim, Jae-Wook;Koh, Yoon-Woo;Kim, Do-Jin;Lee, Seung-Won
    • Korean Journal of Bronchoesophagology
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    • v.15 no.1
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    • pp.50-55
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    • 2009
  • Objectives: Endoscopic airway dilatation and stenting has been developed to treat the airway stenosis without potential morbidities of open surgery. We report the clinical results of endoscopic airway dilatation with silicone stenting in patients with posttuberculous bronchial stenosis(PTBS) and with severe main tracheal stenosis who have poor general conditions Methods : A prospective observation study of five patients, who have undergone endoscopic airway dilatation and silicone stenting between Feb 2007 and Feb 2009. A total of twelve patients were treated with endoscopic airway dilatation, among them 5 patients were included in this study. three patients were treated with newly designed silicone stent (Natural stent: TNO Co., Seoul, South Korea) because of poor surgical conditions and longer stenotic segment Results: 3 patients were grade III PTBS, and the other 2 patients were grade IV post tracheotomy main tracheal stenosis. One patient of PTBS were treated with silicone stent following endoscopic dilatation because of longer stenotic segment. Two patients of main tracheal stenosis patients were treated with silicone stent because of tracheal lumen collapse. There was no severe postoperative complications except mild granulation tissue formations Conclusions : Endoscopic dilatation including silicone stenting could be a useful method for treating patients with PTBS, and for main tracheal stenosis patients with poor general surgical conditions

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Investigation of Recovery Characteristic in Silicone Rubber Used for Outdoor Insulation by Measuring Leakage Current (누설전류 측정을 통한 옥외용 실리콘 절연재의 회복특성)

  • Huh, Chang-Su;Youn, Bok-Hee;Lee, Sang-Youb;Lee, Jong-Han
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1605-1607
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    • 1999
  • Silicone rubber have presently been using in large number for a variety of outdoor HV applications. Silicone rubber have the properties of low surface energy and are able to retain its hydrophobicity or water repellency, thereby suppress the leakage current in the present of moisture and contamination. In this paper, we investigated the recovery characteristics of silicone rubber by measuring the leakage current under salt-fog.

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Breakdown characteristics of EPDM/XLPE laminate (XLPE /EPDM laminate의 절연파괴 특성)

  • Nam, Jin-Ho;Suh, Kwang-S.
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1596-1598
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    • 1999
  • In order to determine what influences the interfacial breakdown between two internal dielectric surfaces. We studied the interfacial breakdown phenomena at several interfacial conditions. With the increase of interfacial pressure, at first breakdown strength in interfaces was increased, and then saturated. Breakdown strength in interface pasted with silicone oil was higher than that with silicone grease. As a function of heat treatment time in a vacuum oven interfacial breakdown strength was increased much in XLPE/EPDM laminates pasted with silicone grease but increased a little in that with silicone oil. As an increase of curing agent in silicone oil and grease, breakdown strength in interfaces was increased and then saturated.

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A Study on Anti-Pollutions Characteristics of RTV Silicone Rubber (RTV 실리콘 고무의 내오손 특성에 관한 연구)

  • Huh, Chang-Su;Lee, Sang-Youb;Youn, Bok-Hee;Hwang, Myung-Kun;Lee, Jong-Han
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1651-1653
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    • 1999
  • Room Temperature Vulcanizing (RTV) Silicone Rubber has been widely used to coat porcelain insulator to prevent formation water filming on insulator surface. and RTV silicone rubber has water repellency to suppress leakage current and consequent flashover. RTV silicone rubber's surface has been degradated by outdoor condition such as dust, salt, and water. etc. ESDD(Equivalent Salt Deposit Density) and leakage currents are increased by polymer surface toughness and degradation. In this paper, we investigated relations of surface toughness, ESDD, and leakage currents.

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