Effect of thermal aging on the crystal structural characteristics of poly(tetra fluoro ethylene)

Jain, Anjana; Vijayan, Kalyani

doi:10.1002/pen.20906

Cited by 9 publications

(3 citation statements)

References 23 publications

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“…A reduction in Nomex® fiber crystallinity measured by X‐ray has also been reported as a result of thermal aging 6. For its part, PTFE has been shown to experience an increase in crystallinity both when thermally aged below its melting temperature of 327°C9 and as a result of argon ion implantation 10…”

Section: Introductionmentioning

confidence: 94%

Effect of thermal aging on the mechanical and barrier properties of an e‐PTFE/Nomex® moisture membrane used in firefighters' protective suits

Aidani

Dolez

Vu‐Khanh

2011

J of Applied Polymer Sci

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Moisture membranes play a key role in high performance protective clothing by preventing outside water to get in while allowing the human body to perspire properly. However, these membranes are confronted to high environmental constraints, in particular within firefighters' protective clothing. The resulting aging effect may lead to modifications of their performances, for example their mechanical or barrier properties. In this study, the thermal aging of an e-PTFE/NomexV R moisture membrane was carried out at five temperatures between 190 and 320 C. The effect of aging on the mechanical performance was assessed by tensile tests and trapezoid tear strength measurements. Variation in the moisture membrane water vapor permeability due to aging was also studied. Large modifications in the membrane mechanical properties as a result of thermal aging were recorded. It was associated in part with a degradation of the NomexV R fibers. The membrane water vapor permeability was observed to decrease with aging time below 220C while values larger than those corresponding to the unaged material were measured above that temperature. This was possibly related to the occurrence of two competing phenomena relative to water vapor permeability: closure of pores in the e-PTFE laminate and creation of cracks and holes. These results show that the aging of the moisture membrane must be considered carefully while estimating the service life of protective clothing.

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Section: Introductionmentioning

confidence: 94%

Effect of thermal aging on the mechanical and barrier properties of an e‐PTFE/Nomex® moisture membrane used in firefighters' protective suits

Aidani

Dolez

Vu‐Khanh

2011

J of Applied Polymer Sci

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“…Thus, we can observe the light on the whole POF. The outer layer of POF can choose the medical polymer material, such as Poly Methyl Methacrylatemethacrylic Acid (PMMA) [30], [31], Poly Tetra Fluoro Ethylene (PTFE) [32], [33], and others. The POF mainly includes two components: outer layer and central layer, and the schematic diagram is shown in Figure 2.…”

Section: B Image Acquirement Methodsmentioning

confidence: 99%

Laparoscopic Image-Guided System Based on Multispectral Imaging for the Ureter Detection

Yu¹,

Song²,

Liu³

et al. 2019

IEEE Access

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The iatrogenic ureter injury is a common medical negligence in the gynecology, abdominal, and urinary surgeries. Anatomically, the ureter is covered by peritoneum and connective tissue, and the doctor cannot observe it directly in surgery. The ureter injury may cause significant complications for patients and medical disputes. It is important to indicate the ureter position for aided surgery of the doctor. To provide ureter position for doctors in the laparoscopic surgery, we design an image-guided endoscope system that includes a novel endoscopic video system with a visible-light camera and an infrared camera. The visible-light camera is to capture the coeliac image and the infrared camera is to capture the ureter position, simultaneously. To extract accurate ureter position in the infrared image, we also propose a self-adaptive threshold segmentation algorithm to extract the real ureter position as accurately as possible. The self-adaptive threshold and scattering factor are taken in to full account for the ureter segmentation. In addition, the scattering property of light is also discussed to choose the optimal light. Finally, we design and develop the image-guided endoscope system, and experiment it on the animal. The experimental results demonstrate that the proposed image-guided endoscope system achieves 93.8% and 90.6% in terms of true positive rate and positive predictive value, respectively. The processing speed of the proposed algorithm can reach about 165 frames per second (f/s), and the frame rate is far faster than the frame rate (30 f/s) of the traditional endoscope system. The accuracy and processing ability of the system can satisfy the clinical demand. The iatrogenic ureter injury may be decreased when the surgeons perform the operations with the ureter position displayed in real time. INDEX TERMSEndoscope system, ureter injury, image-guided, multispectral imaging, ureter detection.

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“…According to XRD observation [9], the initial hexagonal arrangement of PTFE chains is left unaffected by thermal exposure at 360 'C. But the unit cell registers a residual anisotropic volume expansion, IExternal Sample Electrodes which results in a decrease of real permittivity.…”

Section: Permittivity Measurementsmentioning

confidence: 99%

Dielectric Properties of PTFE Wiring Insulation as a Function of Thermal Exposure

Bowler

Yoon

et al. 2008

2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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The study of polymers used in electrical insulation of wiring is important to the aerospace industry due to potential loss of life and aircraft in the event of an electrical fire caused by breakdown of wiring insulation. In this work, the effect of thermal exposure on the permittivity of PTFE is studied in order to examine the feasibility of developing of a capacitive nondestructive testing method to indicate the presence of a significant defect in the wiring insulation, following thermal exposure, by measuring its permittivity. Measurements of permittivity, obtained using a Novocontrol dielectric spectrometer with a temperature-controlled sample cell, reveal a significant reduction in permittivity as a function of duration of heat exposure at 360 'C. The capacity of PTFE samples was also measured over the frequency range 1 Hz to 1 MHz at various temperatures from -150 to 300°C.

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Effect of thermal aging on the crystal structural characteristics of poly(tetra fluoro ethylene)

Cited by 9 publications

References 23 publications

Effect of thermal aging on the mechanical and barrier properties of an e‐PTFE/Nomex® moisture membrane used in firefighters' protective suits

Effect of thermal aging on the mechanical and barrier properties of an e‐PTFE/Nomex® moisture membrane used in firefighters' protective suits

Laparoscopic Image-Guided System Based on Multispectral Imaging for the Ureter Detection

Dielectric Properties of PTFE Wiring Insulation as a Function of Thermal Exposure

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