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Relevant bibliographies by topics / Polytetrafluoroethylene expanse

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Academic literature on the topic 'Polytetrafluoroethylene expanse'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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Journal articles on the topic "Polytetrafluoroethylene expanse"

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Bui, Hieu T., Aidan RW Friederich, Emily Li, David A. Prawel, and Susan P. James. "Hyaluronan enhancement of expanded polytetrafluoroethylene cardiovascular grafts." Journal of Biomaterials Applications 33, no. 1 (2018): 52–63. http://dx.doi.org/10.1177/0885328218776807.

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Heart disease continues to be the leading cause of death in the United States. The demand for cardiovascular bypass procedures increases annually. Expanded polytetrafluoroethylene is a popular material for replacement implants, but it does have drawbacks such as high thrombogenicity and low patency, particularly in small diameter grafts. Hyaluronan, a naturally occurring polysaccharide in the human body, is known for its wound healing and anticoagulant properties. In this work, we demonstrate that treating the luminal surface of expanded polytetrafluoroethylene grafts with hyaluronan improves hemocompatibility without notably changing its mechanical properties and without significant cytotoxic effects. Surface characterization such as ATR-FTIR and contact angle goniometry demonstrates that hyaluronan treatment successfully changes the surface chemistry and increases hydrophilicity. Tensile properties such as elastic modulus, tensile strength, yield stress and ultimate strain are unchanged by hyaluronan enhancement. Durability data from flow loop studies demonstrate that hyaluronan is durable on the expanded polytetrafluoroethylene inner lumen. Hemocompatibility tests reveal that hyaluronan-treated expanded polytetrafluoroethylene reduces blood clotting and platelet activation. Together our results indicate that hyaluronan-enhanced expanded polytetrafluoroethylene is a promising candidate material for cardiovascular grafts.

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Legeais, JM, and G. Renard. "KERATOPROSTHESIS: EXPANDED POLYTETRAFLUOROETHYLENE SUPPORT STUDY." International Ophthalmology Clinics 29, no. 1 (1989): 19. http://dx.doi.org/10.1097/00004397-198902910-00006.

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McCulloch, Timothy M., and Henry T. Hoffman. "Medialization Laryngoplasty with Expanded Polytetrafluoroethylene." Annals of Otology, Rhinology & Laryngology 107, no. 5 (1998): 427–32. http://dx.doi.org/10.1177/000348949810700512.

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Symptomatic unilateral laryngeal paralysis may be treated successfully by a wide variety of surgical techniques. These techniques share the concept that stabilization of the paralyzed vocal fold in a median position will improve glottic function. Medialization laryngoplasty with expanded polytetrafluoroethylene (ePTFE) incorporates the general principles of established medialization procedures, yet is unique in its simplicity. The technique does not require special instrumentation, employs incremental adjustment of vocal fold position, and utilizes an implantable material with a long history of patient safety. We describe this new technique and report on the outcome of our first 16 patients treated. No surgical or implant-related complications have occurred. Voice results were measured from preoperative and postoperative video and voice recordings by four independent observers using a standardized assessment tool. Voice grade and breathiness were evaluated on a four-point scale (0 = normal and 3 = abnormal, extreme). The mean overall grade improved from 2.3 ± 0.6 to 1.1 ± 0.6, and breathiness from 2.0 ± 0.8 to 0.4 ± 0.4. The technique is simple, the implant material has been in clinical use for decades, and the voice results are good to excellent.

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Deysine, Maximo. "Hernia repair with expanded polytetrafluoroethylene." American Journal of Surgery 163, no. 4 (1992): 422–24. http://dx.doi.org/10.1016/0002-9610(92)90045-s.

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Uhl, Christian, Carolin Hock, Thomas Betz, Markus Greindl, Ingolf Töpel, and Markus Steinbauer. "Comparison of venous and HePTFE tibial and peroneal bypasses in critical limb ischemia patients unsuitable for endovascular revascularization." Vascular 23, no. 6 (2015): 607–13. http://dx.doi.org/10.1177/1708538114568701.

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Background We examined short- and long-term outcomes of tibial and peroneal venous and heparin-bonded expanded polytetrafluoroethylene bypasses in patients with critical limb ischemia who were unsuitable for endovascular revascularization. Methods A retrospective analysis was done for all patients who underwent tibial and peroneal bypass surgery in our department between October 2007 and October 2012. Vein was the preferred graft material and used whenever possible. Results One hundred and ninety-eight crural grafts were included. Indications for the surgery were rest pain (30.3%) or ulcer or gangrene (69.7%). Autologous veins were used in 109 cases (vein group) and heparin-bonded expanded polytetrafluoroethylene grafts were used in 89 cases (heparin-bonded expanded polytetrafluoroethylene group). At three years, primary patency for the vein group was 68.2% versus 34.1% for the heparin-bonded expanded polytetrafluoroethylene group ( P = .000) and secondary patency was 69.8% versus 35.5% ( P = .001). Limb salvage was 81.8% for the vein group versus 56.5% for the heparin-bonded expanded polytetrafluoroethylene group ( P = .000) and survival was 62.8% versus 46.7% ( P = .019). Conclusions The results of our study show that autologous vein grafts are still first choice for tibial and peroneal bypasses in patients with critical limb ischemia. If no adequate vein is available, heparin-bonded expanded polytetrafluoroethylene bypasses are an acceptable alternative to an otherwise impending major amputation.

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Hanff, Gunnar, Lars B. Dahlin, and GÖRan Lundborg. "Reconstruction of Ligaments with Expanded Polytetrafluoroethylene." Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery 26, no. 1 (1992): 43–49. http://dx.doi.org/10.3109/02844319209035182.

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Butany, Jagdish, Michael J. Collins, and Tirone E. David. "Ruptured synthetic expanded polytetrafluoroethylene chordae tendinae." Cardiovascular Pathology 13, no. 3 (2004): 182–84. http://dx.doi.org/10.1016/s1054-8807(04)00006-7.

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Cox, Sue Ellen. "Who Is Still Using Expanded Polytetrafluoroethylene?" Dermatologic Surgery 31 (November 2005): 1613–15. http://dx.doi.org/10.2310/6350.2005.31249.

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Branson, Denis F., George J. Picha, and John Desprez. "Expanded Polytetrafluoroethylene as a Microvascular Graft." Plastic and Reconstructive Surgery 76, no. 5 (1985): 754–63. http://dx.doi.org/10.1097/00006534-198511000-00017.

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Aumsuwan, Nattharika, Sabine Heinhorst, and Marek W. Urban. "Antibacterial Surfaces on Expanded Polytetrafluoroethylene; Penicillin Attachment." Biomacromolecules 8, no. 2 (2007): 713–18. http://dx.doi.org/10.1021/bm061050k.

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Dissertations / Theses on the topic "Polytetrafluoroethylene expanse"

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Gravier, Nicolas. "L'utilisation du polytetrafluoroethylene expanse (gore-tex) en chirurgie palpebrale." Nancy 1, 1990. http://www.theses.fr/1990NAN11059.

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CAVIGNEAUX, DECOURTEIX-TURQUET ISABELLE. "Techniques chirurgicales dans la suspension palpebrale pour la cure du ptosis : etude a propos de 6 cas personnels." Limoges, 1988. http://www.theses.fr/1988LIMO0152.

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Vavlekas, Dimitrios A. "Role of fibrillation on Poisson's ratio of expanded polytetrafluoroethylene (PTFE)." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62175.

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The polytetrafluoroethylene (PTFE) paste extrusion was studied to elucidate the role of structure formation (fibrillation) on the Poisson’s ratio of final products such as stents and other implants. In particular two types of PTFE have been studied in capillary extrusion using dies having different reduction ratios (RR) and die entrance angles. The extrudates collected at different processing conditions, were tested in uniaxial extension to assess their mechanical properties. The tensile modulus, yield stress and ultimate tensile strength of the obtained extrudates were found to be increasing functions of reduction ratio, although the opposite effect was found for the ultimate elongational strain. Moreover, a PTFE paste was extruded using a capillary rheometer at various temperatures through cylindrical dies of different reduction ratios (1-D structure samples). Uniaxial tensile experiments were performed on the collected extrudates using the SER at different temperatures and Hencky strain rates. A nonlinear viscoelastic model (Matsuoka) was used to model the transient tensile results. An empirical model was also developed to predict the tensile ultimate strength as a function of processing conditions such as temperature and die reduction ratio, as well as, the testing operating conditions i.e., temperature and Hencky strain rate. PTFE flat profiles were extruded using slit dies, which promoted orientation of fibrils in two directions (2-D structure samples). Uniaxial tensile experiments were performed on the collected extrudates using the SER at different temperatures and Hencky strain rates to determine mechanical properties. Poisson’s ratio was determined using image analysis and the results were compared using data from the 1-D structure samples. Polarized Raman spectroscopy was used to gain additional information on the degree of fibril orientation at different locations along and across the width and length of the extrudates. Finally, a simple model was derived for the density change in tensile deformation by taking into the account the Poisson’s ratio and the strain recovery. Results of the Raman spectra and the strain recovery coefficient from density changes, were found to be in agreement with the fibril structure/morphology obtained from SEM micrographs.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

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Schwartz, Mark Aaron. "Molecular and Cellular Dynamics of the Healing Response Associated with Implanted Expanded Polytetrafluoroethylene." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1410%5F1%5Fm.pdf&type=application/pdf.

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Query, Michael Earl. "Ultrasound-induced thermal therapy of hyperplasia in ringed expanded polytetrafluoroethylene (eptfe) access grafts." Thesis, The University of Utah, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1553446.

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Hemodialysis vascular access, the interface between a dialysis patient and a dialysis machine, is quite literally the lifeblood of a patient's health. Vascular access dysfunction is the leading cause of hospitalization in hemodialysis patients. The occlusive growth of neointimal hyperplasia (NH) in expanded polytetrafluoroethylene (ePTFE) ringed grafts is the primary cause of failure. To further develop a proposed thermal ultrasound treatment to reduce or prevent NH in arteriovenous vascular grafts, the acoustic properties of ePTFE were studied in water and alcohol solutions. Previous reports of ePTFE acoustic properties are critiqued. It was found that the acoustic transmission and attenuation through ePTFE, and therefore the potential for an ultrasound-based therapy for NH, are heavily dependent on the medium in which the graft is immersed, suggesting that the acoustic properties of implanted grafts will change as grafts mature in vivo. The acoustic impedance and attenuation of water-soaked ePTFE were 0.478 ± 1.43 × 10^-2 MRayl and 1.78 ± 0.111 Np/cm*MHz, respectively, while the acoustic impedance and attenuation of ePTFE in alcohol were 1.49 ± 0.149 MRayl and 0.77 ± 1.1 × 10^-2 Np/cm*MHz, respectively. The use of focused ultrasound to heat implanted ringed ePTFE grafts was numerically modeled from 1.35- and 1.443-MHz transducers for in vitro geometries. Power deposition and heating, in turn, differed by an order of magnitude between various graft acoustic properties. Graft rings were predicted to be substantial absorbing and scattering features. In vitro phantom models were constructed: one with and one without thermocouples. At 1 W of acoustic power, the maximum temperature rise was 8˚ C. The thermocouple model containing a water-soaked graft did not experience heating in the far graft wall. The MRTI model confirmed that the graft rings are an absorbing/scattering feature. Heating was not prevented in the presence of water flow through the graft. Water was not heated significantly. Overall, results suggest ultrasound exposure can be used to generate temperature rises corresponding with the potential prevention or inhibition of NH in ringed ePTFE vascular grafts. A hybrid therapeutic/diagnostic transducer design with a therapeutic semi-annular array surrounding a diagnostic linear array is presented. Compared to a solid transducer of the same dimensions, there were only marginal aberrations in the focal plane. Numerical optimization of the element drive configuration indicated that the least distorted focal plane was produced by uniform phase and magnitude at each element.

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Musil, Ian, Vanessa Jensen, Jolyon Schilling, Boyd Ashdown, and Tyler Kent. "Enterobacter cloacae infection of an expanded polytetrafluoroethylene femoral-popliteal bypass graft: a case report." BioMed Central, 2010. http://hdl.handle.net/10150/610188.

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INTRODUCTION:Enterobacter cloacae infections are common among burn victims, immunocompromised patients, and patients with malignancy. Most commonly these infections are manifested as nosocomial urinary tract or pulmonary infections. Nosocomial outbreaks have also been associated with colonization of certain surgical equipment and operative cleaning solutions. Infections of an aortobifemoral prosthesis, an aortic graft, and arteriovenous fistulae are noted in the literature. To our knowledge, this is the first isolated account of an E. cloacae infection of a femoral-popliteal expanded polytetrafluoroethylene bypass graft.CASE PRESENTATION:A 68-year-old Caucasian man presented with fever and rest pain in the right lower extremity five months after the placement of a vascular expanded polytetrafluoroethylene graft for femoral-popliteal bypass. Computed tomography angiography demonstrated peri-graft fluid that was aspirated percutaneously with image guidance and cultured to reveal E. cloacae. The graft was revised and then removed. The patient completed a six-week course of ceftazidime and is currently without signs of infection. There were no other reports of E. cloacae graft infections in any patients receiving treatment in the same surgical suite within a month of this report.CONCLUSION:Isolated cases of E. cloacae infection of surgical bypass grafts are rare (unique in this setting). Clinicians should have a high index of suspicion for device contamination in such cases and should consider testing for possible microbial reservoirs. Graft removal is required due to the formation of biofilm and the recent emergence of Enterobacteriaceae producing extended-spectrum beta-lactamase in community acquired infections.

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Rodrigues, Rui Alexandre Cardoso. "Regeneração óssea vertical na reabilitação com implantes: resultados a longo prazo." Master's thesis, [s.n.], 2015. http://hdl.handle.net/10284/5280.

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária
Os procedimentos de Regeneração Óssea Guiada (ROG) visam fornecer ao paciente melhoras, a nível estético e funcional, aumentando o volume e disponibilidade óssea. Actualmente realizam-se procedimentos para aumento do rebordo ósseo com o intuito de possibilitar a colocação de implantes dentários e melhorar a sua estética. Será descrita nesta revisão bibliográfica a Regeneração Óssea Guiada (ROG) para aumento vertical do rebordo alveolar e posterior colocação de implantes, bem como a previsibilidade da técnica e as suas taxas de sucesso. Existem vários materiais disponíveis para a técnica de ROG vertical, porém as membranas de politetrafluoroetileno expandido não-reabsorvível (PTFE-e) com reforço de titânio em associação com enxerto (1:1) autógeno e mineral de osso bovino desproteinizado (DBBM) constituem, actualmente, a primeira escolha quando se pretende o aumento ósseo vertical. A ROG para aumento vertical, apresenta boas taxas de sucesso e previsibilidade, contudo necessita de um operador com experiencia pois é uma técnica de muita exigência. Esta técnica pode ser realizada prévia ou em simultâneo com a colocação dos implantes.
Guided Bone Regeneration (GBR) procedures aim to provide the patient with aesthetical and functional improvements, increasing the bone volume and availability. Currently, procedures to increase the bone ridge are undertaken with the objective of allowing the placement of dental implants and improve their aesthetical appeal. Guided Bone Regeneration (GBR) for the vertical augmentation of the alveolar ridge and consequent implant placement will be described in this bibliographical review, as well as the predictability of the technique and its success rates. There are several materials available for the vertical GBR technique, however the membranes of expanded non-resorbable polytetrafluoroethylene (PTFE-e) with titanium reinforcement in association with autogenous graft (1:1) and deproteinized bovine bone mineral (DBBM) currently represent the first choice when a vertical bone augmentation is intended. The GBR for vertical augmentation features good success rates and predictability, however it requires an experienced operator, as it is a demanding technique. This can be performed previously or simultaneously with the placement of implants.

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Hernández, Tecanhuey Gerardo. "Uses and techniques of Polytetrafluoroethylene (PTFE) in dentistry." Master's thesis, 2018. http://hdl.handle.net/10284/7232.

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Due to its versatility, polytetrafluoroethylene ( PTFE ), is widely applied in dentistry and offers many advantages for its clinical use. The need to put in one paper the largest number of techniques, in which PTFE is used, is the main reason for conducting this literature review. The source of literature were international data bases: B-on, Pub Med, SciELO, ScienceDirect, Web of Science, searched by keywords with inclusion and exclusion criteria for a previous selection of the papers. For the analysis these techniques will be grouped in the different areas of dentistry to which correspond, such as : conservative dentistry, peri-implant surgery, orthodontics, endodontics and oral hygiene. The organization and description of techniques conducted in this study allows to identify the main functions that PTFE serves in dentistry, which are: mechanical barrier; filling or packing material; spacer element to simulate cement layer; surface coating; biofilm removal instrument.
Devido à sua versatilidade, o politetrafluoretileno (PTFE) é amplamente aplicado na odontologia e oferece muitas vantagens para o seu uso clínico. A necessidade de colocar num documento o maior número de técnicas, nas quais o PTFE é utilizado, é a principal razão para a realização desta revisão de literatura. A fonte da literatura foram bancos de dados internacionais: B-on, PubMed, SciELO, ScienceDirect, Web of Science, pesquisados usando palavras-chave com critérios de inclusão e exclusão para a seleção prévia dos artigos. Para sua análise estas técnicas serão agrupadas nas diferentes áreas da odontologia a que correspondem, tais como: odontologia conservadora, cirurgia peri-implantar, ortodontia, endodontia e higiene bucal. A organização e descrição das técnicas conduzidas neste estudo permitem identificar as principais funções que o PTFE atende em odontologia, que são: barreira mecânica; enchimento ou material de embalagem; elemento espaçador para simular camada de cimento; revestimento de superfície; instrumento de remoção de biofilme.

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Books on the topic "Polytetrafluoroethylene expanse"

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Kahn, S. Lowell, and Sergio Rojas. Deployment Finesse of the Gore Excluder Stent Graft. Edited by S. Lowell Kahn, Bulent Arslan, and Abdulrahman Masrani. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199986071.003.0002.

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The Gore Excluder stent graft was approved for use in the United States by the US Food and Drug Administration (FDA) in 2002. The Excluder is a modular, bifurcated endoprosthesis utilized in the treatment of abdominal aortic aneurysms. The Excluder endoprosthesis is constructed from an expanded polytetrafluoroethylene film and an incorporated “weldless” nickel–titanium stent skeleton for support. The device features no sutures, infrarenal fixation, and is made to be inserted through 12–18 Fr introducer sheaths. Since its approval by the FDA, the Excluder has undergone multiple changes, including profile reductions, the addition of an impermeable membrane (due to early graft material design associated with type IV endoleaks), and, most notably, a repositioning mechanism labeled the C3 Excluder. This chapter discusses multiple techniques of deployment of the Gore Excluder stent graft.

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Book chapters on the topic "Polytetrafluoroethylene expanse"

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Law, Nicholas. "Expanded Polytetrafluoroethylene." In Abdominal Wall Hernias. Springer New York, 2001. http://dx.doi.org/10.1007/978-1-4419-8574-3_37.

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Wikol, Michael, Bryce Hartmann, Michael Debes, Cherish Robinson, Scott Ross, and Uwe Beuscher. "Expanded Polytetrafluoroethylene Membranes and Their Applications." In Filtration and Purification in the Biopharmaceutical Industry. CRC Press, 2019. http://dx.doi.org/10.1201/9781315164953-20.

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Steinsapir, Kenneth D. "Midface Lifting with Expanded Polytetrafluoroethylene Orbital Rim Implants." In Midfacial Rejuvenation. Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1007-2_8.

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Tokiwa, T., J. Kano, X.-Y. Meng, M. Kodama, and T. Matsumura. "Morphology and Function of Rat Hepatocytes Cultured on Expanded Polytetrafluoroethylene Surface." In Animal Cell Technology: Basic & Applied Aspects. Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5161-0_50.

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Ahlfeld, S. K., R. L. Larson, and H. R. Collins. "Anterior Cruciate Ligament Reconstruction in the Chronically Unstable Knee Using an Expanded Polytetrafluoroethylene (PTFE) Prosthetic Ligament." In Surgery and Arthroscopy of the Knee. Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-72782-5_45.

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LeBlanc, K. A. "Two-Phase In Vivo Comparison Studies of the Tissue Response to Polypropylene, Polyester, and Expanded Polytetrafluoroethylene Grafts Used in the Repair of Abdominal Wall Defects." In Peritoneal Adhesions. Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-60433-1_44.

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Ebnesajjad, Sina. "Polytetrafluoroethylene." In Expanded PTFE Applications Handbook. Elsevier, 2017. http://dx.doi.org/10.1016/b978-1-4377-7855-7.00002-x.

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Ebnesajjad, Sina. "Expansion of Polytetrafluoroethylene Resins." In Expanded PTFE Applications Handbook. Elsevier, 2017. http://dx.doi.org/10.1016/b978-1-4377-7855-7.00005-5.

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Ebnesajjad, Sina. "Surface Modification of Expanded Polytetrafluoroethylene." In Expanded PTFE Applications Handbook. Elsevier, 2017. http://dx.doi.org/10.1016/b978-1-4377-7855-7.00013-4.

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Ebnesajjad, Sina. "Manufacturing Polytetrafluoroethylene by Emulsion Polymerization." In Expanded PTFE Applications Handbook. Elsevier, 2017. http://dx.doi.org/10.1016/b978-1-4377-7855-7.00003-1.

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Conference papers on the topic "Polytetrafluoroethylene expanse"

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Legeais, Jean-Marc, Gilles Renard, Jean-Marie A. Parel, Gabriel Simon, and Yves Pouliquen. "Artificial cornea: cellular ingrowth and transparency of an expanded polytetrafluoroethylene." In OE/LASE '92, edited by Jean-Marie Parel. SPIE, 1992. http://dx.doi.org/10.1117/12.137412.

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Kanthabhabha Jeya, Rahul Palaniappan, and Abdel-Hakim Bouzid. "Characterisation of Polytetrafluoroethylene and Fiber Based Gaskets Under Creep and Thermal Ratcheting." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65271.

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The objective of this research work is to typify PolyTetraFluoroEthylene (PTFE) and fiber based gaskets. Recurrent employment of Teflon based gaskets as asbestos gasket replacement in certain applications is due to their effective leak tightness and excellent chemical resistance. The research investigates the effect of cyclic and determinant temperature on the phenomenon of creep and thermal ratcheting under compressive load. The tests are performed at 4000 and 6000 psi compressive stress on virgin PTFE (vPTFE) and expanded PTFE (ePTFE) along with Inorganic Fiber Gaskets (IFG) at different temperatures. The Universal Gasket Rig (UGR) is utilized to perform the convoluted analysis of creep-thermal ratcheting coupling at different stress levels on selected gasket materials. The actual cumulative damage due to thermal ratcheting is separable into upper and lower bound regions indicating the highest and lowest of ratcheting temperature regions. The effect of thermal ratcheting tends to saturate after 12 and 15 cycles for expanded PTFE and fiber gaskets while no saturation is observed with virgin PTFE gaskets even after 20 thermal cycles. IFG and virgin PTFE gaskets exhibited similar percentage of thickness reduction under different applied stresses while expanded PTFE showed a maximum reduction under the least applied stress. The influences of temperature and load are manifested in the compressive creep property which in turn dictates the magnitude of cumulative damage due to thermal ratcheting. Lastly, the impact of creep and thermal ratcheting on the Coefficient of Thermal Expansion (CTE) is evident as the magnitude of CTE upsurges with the extent of induced damage.

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JOHNSON, MICHAEL. "Expanded PTFE (polytetrafluoroethylene) fibers - Extending the limits of textile technology in aerodynamic decelerator systems." In 10th Aerodynamic Decelerator Conference. American Institute of Aeronautics and Astronautics, 1989. http://dx.doi.org/10.2514/6.1989-913.

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Zhu, Guangyu, Masakazu Nakao, Qi Yuan, and Joon Hock Yeo. "in-vitro Assessment of Expanded-Polytetrafluoroethylene Stentless Tri-leaflet Valve Prosthesis for Aortic Valve Replacement." In 10th International Conference on Biomedical Electronics and Devices. SCITEPRESS - Science and Technology Publications, 2017. http://dx.doi.org/10.5220/0006184401860189.

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Chen, Wei-Ling, and Chung-Dann Kan. "In Vitro Hemodynamic Evaluation of Right Ventricle–Pulmonary Artery Continuity Reconstruction Through a Trileaflet Expanded Polytetrafluoroethylene Valved Conduit." In 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE, 2018. http://dx.doi.org/10.1109/embc.2018.8513179.

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Zahedmanesh, Houman, Paul Gatenholm, and Caitríona Lally. "Bacterial Cellulose: A Potential Vascular Graft and Tissue Engineering Scaffold." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206343.

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Cardiovascular disease is the major cause of morbidity and mortality in the adult population and treatment of many of the patients struggling with such diseases requires surgical interventions involving replacement of diseased arteries. Although currently it is possible to replace large arteries with synthetic grafts made of materials such as polyester and expanded polytetrafluoroethylene (ePTFE) [1], these materials may not be used as small size grafts given their thrombogenicity and propensity for intimal hyperplasia [2]. As a result, development of suitable grafts as a substitute for small size arteries (< 6mm in diameter) such as the coronary arteries remains a daunting challenge.

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Czerwinski, John, Vijay K. Garikipati, Charlene N. Jones, et al. "A Collaborative Approach to Achieving a Gas-Tight Seal Using Expanded Polytetrafluorethylene (ePTFE) Gaskets in a Fiberglass-Reinforced Plastic (FRP) Lap-Joint Flanges." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78847.

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The work presented here is a collaborative approach to achieving a reliable gas tight seal in fiberglass reinforced plastic (FRP) flanged joints using expanded polytetrafluoroethylene (ePTFE) gaskets. There are many advantages to incorporating FRP flanged piping systems in today’s chemical process industry plant build. As regulations on reliability and fugitive emissions become stricter, it is more important than ever to eliminate possible damage and leak paths at the flanged connections in these systems. This paper details a case study on a collaboration between a chemical plant operator (end user), an ePTFE gasket manufacturer, and a FRP piping original equipment manufacturer. Over a twenty-four month period a FRP flanged system was designed and validated using a custom FRP stub and ring, also known as a lap joint, flange with an ePTFE gasket. The result was the development of a FRP bolted flange system that successfully achieved a reliable gas tight seal for aggressive chemicals. Beginning with a theoretical model and ending with experimental lab analyses, the conclusive results are included herein.

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Silva, Ana C., Florian Werner, and Lucas Xavier. "The Influence of Elevated Temperature in Creep Relaxation of Various PTFE Gaskets Production Methods." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84077.

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Abstract:

Polytetrafluoroethylene (PTFE) products have been widely used for industrial sealing applications due to their outstanding chemical resistance as well as their electrical, anti-stick, impact resistance and low friction properties. Diverse PTFE flat gaskets production methods are available in the industry, which include the combination of a selected Resin Type and a determined manufacturing process, being able to provide a wide range of several types of PTFE gaskets, with different mechanical characteristics. The production method has significant impact on the mechanical properties of the PTFE gaskets, especially the creep relaxation property at elevated temperatures. Therefore, the gasket behavior at high temperatures and, consequently, the bolted flanged joint (BFJ) performance, directly depends on both selected Resin Type and gasket manufacturing process. One of the most used PTFE gasket types is produced from multiaxially expanded PTFE sheets. As it is known, different types of stretching, among other factors, confer to the gasket particular mechanical characteristics. This type of gasket exhibits a very low gasket seating stress, and it is the preferred type for most low bolt load flanges. This paper presents a study of the creep relaxation property at room and elevated temperatures of expanded PTFE gaskets manufactured by different Resin Types and processes of expanding PTFE materials. Experimental results are presented comparing EN 13555 [1] Qsmax, PQR and ΔeGc parameters of the produced PTFE gaskets.

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Grant, Kenneth R., and Tom Lokey. "Gasket Testing Regimen for Transportation Intermediate Bulk Containers." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28771.

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Comprehensive testing using various different gasket types and materials was performed in order to determine the best overall performance in gasket suitability and leakage reliability on an IBC (Intermediate Bulk Container), provided by a tank manufacturer. Prior to testing, the tank was filled with water just below the elevation of the manway, and the remaining space was charged with air. Testing was performed in two phases. Phase 1 was conducted as a simple pressure test with the container in a static state. For Phase 2, a test procedure was developed to include temperature and pressure variations, soak and dwell times, torque value calculations, leakage rates, sustainability, and a simulation of artificial vibration effects on bolted flange connections. Utilizing the Phase 2 procedure gives the ability to compare the various gasket materials under real world conditions, which will reveal the optimum gasket that provides the safest and most reliable connections for the transportation industry. Four corrosion resistant polytetrafluoroethylene (PTFE) based gasket materials were selected to be tested on the IBC. The gasket materials included virgin PTFE, glass-filled PTFE, tanged 316 stainless steel reinforced expanded PTFE (ePTFE), and corrugated 316 stainless steel reinforced expanded PTFE. All testing was performed indoors in a controlled environment. Testing on each gasket type was performed using the same equipment, while following the same test procedures.

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10

Kobayashi, Takashi, and Chihiro Zenyoji. "Effectiveness of Retightening in Maintaining Higher Residual Bolt Loads and Tightness of Bolted Flanged Connections." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45472.

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Abstract:

Bolt loads reduce significantly after tightening of bolted flanged connections in which expanded PTFE (Polytetrafluoroethylene) gaskets are used. Bolts are often retightened after a while to compensate for the reduction of bolt loads in practice. The visco-elastic characteristic of PTFE gaskets is the main cause for the phenomenon. The flexibility of the bolt-flange system also affects the phenomenon. However, effects of the retightening on the residual bolt loads and the tightness of flanged connections have not been clarified yet. In this paper, an analytical model of a bolted flanged connection, in which the flanges, the bolts and the gasket are represented by spring constants, is proposed. The residual bolt forces and the deflection of the gasket were estimated based on the analytical model of the bolted flanged connection and a creep characteristic of the gasket. Thus, the relationship between gasket deflection and the tightness of the bolted flanged connection are clarified. Based on the analytical method, the effectiveness of retightening was discussed from the view points of the residual bolt load and the tightness.

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