• Journal of Chest Surgery
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• v.17 no.4
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• pp.691-697
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• 1984

After the real birth of vascular surgery occurred with the introduction of the first practical arterial prosthesis about 50 years ago, a variety of potential vascular graft had been tested and rejected. Polytetrafluoroethylene [Teflon, PTFE] was first used as a vascular prosthesis in 1957. Thereafter this pros-thesis was first used clinically in 1972 and has subsequently been widely applied as a small and medium sized vessel replacement because it is easy to use and readily available. There are numerous reports of good results about Polytetrafluoroethylene graft. We experienced the three cases of arterial bypass graft using polytetrafluoroethylene vascular pros-thesis. First, 21 years old female patient had suffered from Takayasus disease which affected the left subclavian artery and right subclavian-left axillary extra anatomical bypass graft as done. Second, 64 years old male patient had suffered from Leriche syndrome for 12 years and the left axillofemoral and femorofemoral extra anatomical bypass graft was done. Third, 34 years old male patient had suffered from recurrent Buergers disease which affected the left popliteal artery and the isolated popliteal artery segment bypass graft was done. Relatively satisfactory result was obtained in early post-operative period in all three cases.

• Korean Journal of Bronchoesophagology
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• v.8 no.1
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• pp.22-28
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• 2002

Background and Objectives : The aim of the this study is to determine the efficacy of an external prosthesis made of ringed Polytetrafluoroethylene to prevent Postanastomotic stenosis after surgical correction of extensive tracheal defects in rabbits. Materials and Methods : Thirty rabbits were used, divided into two groups of 15 animals each. Group A rabbits underwent resection of six-ring segments of the cervical trachea and tracheal end-to-end anastomosis. The Procedure used in group B was similar to that used in group A. but the tracheal anastomosis was supported by an external ringed polytetrafluoroethylene prosthesis. After six months, rabbits were killed and tracheas were resected and then compared the postanastomotic tracheal stenosis using morphometry. Results : Anteroposterior diameter, transverse diameter, cross sectional area and intra luminal perimeter of trachea was greater in group B than group A. Also inflammatory changes of mucosa and submucosa were greater in group A than group B. Conclusion : A ringed PTFE as a external stent was effective to prevent tracheal stenosis resulting from the extensive tracheal resection and tracheal reconstruction in rabbits.

• Journal of Chest Surgery
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• v.18 no.2
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• pp.314-319
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• 1985

Nineteen patients with various types of cyanotic congenital heart disease underwent systemic-pulmonary artery shunts with a microporous polytetrafluoroethylene [PTFE] graft between September, 1983, and April, 1985. Age ranged from 3 months to 18 years, and seven of them were less than 12 months old. There were seventeen Great Ormond Street type of modified Blalock-Taussig shunts, and two central polytetrafluoroethylene shunt [ascending aorta-right pulmonary artery]. There was one postoperative death [1/19=5.3%] in a 10 Kg child born with pulmonary atresia and ventricular septal defect associated with patent ductus arteriosus. He had another anomaly of imperforated anus. Relief from cyanosis was achieved in other eighteen patients with variable degree. Eighteen survivors have been followed up from 1 month to 19 months. Clinical status, auscultation, oxygen partial pressure of arterial blood, and hemoglobin have been used to establish shunt patency in all survivors. By above criteria, all survivors have good patent shunt.

• Tribology and Lubricants
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• v.20 no.1
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• pp.1-6
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• 2004

In order to identify the effect of lubricant films on abrasive abilities of diamond films, wear rates of Ruby balls slid over as grown diamond films and polytetrafluoroethylene films coated diamond films were compared by using pin-on-disk tribometer. Wear scars of Ruby balls were measured by SEM. Results showed that wear rates of Ruby balls slid over polytetrafluoroethylene coated diamond films were about 4 times lager than as grown diamond films. Coefficients of friction decreased with sliding distance at diamond disks but were almost unchanged at polytetrafluoroethylene coated ones. These results came from behaviors of wear debris, which adhered more strongly in the tracks of as grown diamond films than polytetrafluoroethylene coated ones.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.102.1-102
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• 2003

• Journal of Powder Materials
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• v.24 no.2
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• pp.102-107
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• 2017

Porous polytetrafluoroethylene (PTFE) thin films are fabricated by spin-coating using a dispersion solution containing PTFE powders, and their crystalline properties are investigated after thermal annealing at various temperatures ranging from 300 to $500^{\circ}C$. Before thermal annealing, the film is densely packed and consists of many granular particles 200-300 nm in diameter. However, after thermal annealing, the film contains many voids and fibrous grains on the surface. In addition, the film thickness decreases after thermal annealing owing to evaporation of the surfactant, binder, and solvent composing the PTFE dispersion solution. The film thickness is systematically controlled from 2 to $6.5{\mu}m$ by decreasing the spin speed from 1,500 to 500 rpm. A triboelectric nanogenerator is fabricated by spin-coating PTFE thin films onto polished Cu foils, where they act as an active layer to convert mechanical energy to electrical energy. A triboelectric nanogenerator consisting of a PTFE layer and Al metal foil pair shows typical output characteristics, exhibiting positive and negative peaks during applied strain and relief cycles due to charging and discharging of electrical charge carriers. Further, the voltage and current outputs increase with increasing strain cycle owing to accumulation of electrical charge carriers during charge-discharge.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.172-179
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• 1998

The effects of $^{60}Co\;{\gamma}-Ray$ irradiation on TSC characteristics of TFE type polytetrafluoroethylene(PTFE) were investigated. The $\alpha$ peak on TSC curve of PTFE was decreased, while the $\beta$ peak was reversely increased by the increasing of $\gamma$-irradiation doses up to 80 krad(0.8 kGy). Moreover, $\alpha$ and $\beta$ peaks on TSC curve of the irradiated PTFE are changed with the increasing of the forming temperature and forming electric field. In annealing the irradiated PTFE specimens at room temperature in air, it was shown a continuous recovery of TSC characteristics with time, which is assumed the traped charge carriers are liberated from the shallow traps and undergoes a recombination process during room temperature decay.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3411-3420
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• 2014

Deficiencies in wear and frost resistance as well as mechanical strength constitute the main causes of equipment failure under the harsh climatic conditions of the Earth's polar regions. To improve the properties of the materials used in this equipment, nanoparticle composites have been prepared from clays such as kaolinite, hectorite, and montmorillonite in combination with polytetrafluoroethylene (PTFE) or ultrahigh molecular weight polyethylene (UHMWPE). A number of techniques have been proposed to disperse silicate particles in PTFE or UHMWPE polymer matrices, and several successful processes have even been widely applied. Polymer nanocomposites that exhibit enhanced mechanical and thermal properties are promising materials for replacing metals and glass in the equipment intended for Arctic use. In this article, we will review PTFE- and UHMWPE-based layered silicate nanocomposites.

• Journal of Chest Surgery
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• v.38 no.5 s.250
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• pp.389-390
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• 2005

We report a case of a 48-year-old woman with end-stage renal failure who had a Polytetrafluoroethylene graft for hemodialysis and who had developed complications of venous outflow stenosis and venous backflow. Although venous backflow is an harbinger of graft failure, it is not enough reason to abandon the graft immediately. The patient was able to utilize her graft for 6 further months.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.34-35
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• 1994

기체혼합물의 분리및 정제기술은 에너지 절약의 관점과 새로운 기능성 고분자의 개발로 고분자막에 의한 분리법이 관심을 끌게되었다. 공기로부터 산소부화, 방사성 크세논 및 크립론의 제거, 제련소 폐가스증의 수소분리, 천연가스로부터 헬륨의 회수분야등은 실제로 산업적으로 실용화되고 있다. 그러나 고분자막은 일반적으로 투과성과 선택성이 서로 상반되는 경향을 나타내므로, 투과성과 분리성이 좋은 기능성 고분자막의 개발에 다양한 연구가 필요로 하고있다. 본 연구에서 사용한 PTFE(polytetrafluoroethylene)는 결정성 고분자로서 넓은 온도범위에서 낮은 마찰계수, 우수한 전기적 절연특성, 강한 Carbon-fluorine 겹합에 기인한 높은 열적 안정성, 화확적 불활성때문에 공업용 고분자 재료로서 독특한 위치를 차지하고 있다. 최근에 미국과 일본을 주축으로 상용화딘 공기전지(Zinc-air battery)는 PTFE막의 뛰어난 소수성과 화학적 저항성으로 수은 전지의 대체품으로 주목받고 있는데, 장기 방전시 성능 저하가 따르므로 막을 통한 산소투과성을 방전에 필요한 최소값으로 감소시키는 것이 중요한 과제가 되고있다.