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PTFE porous membrane technology: A comprehensive review. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2022.121115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Tomkovic T, Hatzikiriakos SG. Rheology and processing of polytetrafluoroethylene (
PTFE
) paste. CAN J CHEM ENG 2020. [DOI: 10.1002/cjce.23816] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tanja Tomkovic
- Department of Chemical and Biological EngineeringThe University of British Columbia Vancouver British Columbia Canada
| | - Savvas G. Hatzikiriakos
- Department of Chemical and Biological EngineeringThe University of British Columbia Vancouver British Columbia Canada
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3
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Ansari M, Vavlekas D, McCoy JL, Hatzikiriakos SG. Paste Extrusion and Mechanical Properties of PTFE. INT POLYM PROC 2015. [DOI: 10.3139/217.3130] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
The paste extrusion process of two types of PTFE has been studied in capillary extrusion using dies having different reduction ratio (RR) and die entrance angles. The extrusion pressure shows a weak increase with shear rate over a wide range of flow rates and a more significant increase with reduction ratio. Moreover, the extrusion pressure exhibits a minimum for entrance angle at around 30°. A simple analytical model based on the radial flow hypothesis (previously developed) has been found to represent the extrusion pressure adequately as a function of flow rate (shear rate) and geometrical characteristics of the capillary dies. The extrudates collected at different processing conditions were dried and tested in uniaxial extension to assess their effect on 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. These mechanical properties are also found to be insensitive to changes in the die entrance angle although the ultimate tensile strength has shown a maximum at the entrance angle of about 60°. The PTFE paste extrudates show a Poisson's ratio equal to zero in tensile experiments, thus exhibiting expansion (significant density reduction with stretching). 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 (recovery of the elastic energy stored upon removal of the tensile stress).
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Affiliation(s)
- M. Ansari
- Chemical and Biological Engineering Department , The University of British Columbia, Vancouver, BC , Canada
| | - D. Vavlekas
- Chemical and Biological Engineering Department , The University of British Columbia, Vancouver, BC , Canada
| | - J. L. McCoy
- Northboro R&D Center – Saint-Gobain , Northborough, MA , USA
| | - S. G. Hatzikiriakos
- Chemical and Biological Engineering Department , The University of British Columbia, Vancouver, BC , Canada
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4
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Ardakani HA, Mitsoulis E, Hatzikiriakos SG. Polytetrafluoroethylene Paste Extrusion: A Fibrillation Model and Its Relation to Mechanical Properties. INT POLYM PROC 2013. [DOI: 10.3139/217.2744] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effects of process conditions on fibrillation and mechanical properties of polytetrafluoroethylene (PTFE) paste extrudates have been studied using capillary rheometers having barrels of different diameter and equipped with capillary dies of various designs. The tensile strength of PTFE extrudates is measured as a function of apparent shear rate (flow rate), reduction ratio (cross sectional area of barrel to that of die), contraction angle, and diameter of the barrel. To describe the effects of die design on the quality of the final product, a basic phenomenological mathematical model has been developed. The model consists of a simple equation that explains fibril formation, due to the compression of PTFE resins, plus a kinetic equation, which is coupled with the “radial-flow” hypothesis to predict the structure and the tensile strength of extrudates. The model predictions are found to be consistent with tensile strength measurements and SEM micrographs of the PTFE extrudates.
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Affiliation(s)
- H. A. Ardakani
- Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC, Canada
| | - E. Mitsoulis
- School of Mining Engineering and Metallurgy, National Technical University of Athens, Athens, Greece
| | - S. G. Hatzikiriakos
- Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC, Canada
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6
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Guney-Altay O, Shenoy SL, Fujiwara T, Irie S, Wynne KJ. Measurement of Supercritical CO2 Plasticization of Poly(tetrafluoroethylene) Using a Linear Variable Differential Transformer. Macromolecules 2008. [DOI: 10.1021/ma8013977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ozge Guney-Altay
- Department of Chemical and Life Science Engineering, 601 W. Main Street, Virginia Commonwealth University, Richmond, Virginia 23284-3028
| | - Suresh L. Shenoy
- Department of Chemical and Life Science Engineering, 601 W. Main Street, Virginia Commonwealth University, Richmond, Virginia 23284-3028
| | - Tomoko Fujiwara
- Department of Chemical and Life Science Engineering, 601 W. Main Street, Virginia Commonwealth University, Richmond, Virginia 23284-3028
| | - Sadashige Irie
- Department of Chemical and Life Science Engineering, 601 W. Main Street, Virginia Commonwealth University, Richmond, Virginia 23284-3028
| | - Kenneth J. Wynne
- Department of Chemical and Life Science Engineering, 601 W. Main Street, Virginia Commonwealth University, Richmond, Virginia 23284-3028
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Patil PD, Isaias O, Stamboulides C, Hatzikiriakos SG, Polastri F, Kapeliouchko V. Paste extrusion of polytetrafluoroethylene (PTFE) powders through tubular and annular dies at high reduction ratios. J Appl Polym Sci 2008. [DOI: 10.1002/app.27681] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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