Teflon physical properties

Mechanical Properties. Table 2 shows the physical properties of Teflon PEA (22,23). At 20—25°C the mechanical properties of PEA, EEP, and PTEE are similar differences between PEA and EEP become significant as the temperature is increased. The latter should not be used above 200°C, whereas PEA can be used up to 260°C. Tests at Hquid nitrogen temperature indicate that PEA performs well in cryogenic appHcations (Table 3). 

Nearly all of the commercially available membranes are based on Nafion. Nafion also has the largest body of literature devoted to its study because of its demonstrated industrial importance and availability. Nafion composite systems also have already become significant in both industrial and academic research. In composite structures, Nafion can be impregnated into an inert Teflon-like matrix (i.e. W. L. Gore membranes ), or inorganic additives can be added to a supporting Nafion matrix for improved physical or electrochemical properties (i.e. lon-omem °). Some critical aspects of Nation s molecular structure and physical properties will be briefly highlighted to provide a baseline for comparison with the other alternative materials discussed in this review. 

Since the discovery of Teflon by Roy Plunkett in 1937 a number of fluorinated plastics have reached commercial status. These plastics, exemplified by polytetrafluoroethylene (PIPE), have outstanding electrical, chemical, and thermal properties. AU these commercial materials are either crystaUine or semicrystalline. Teflon AF is a family of amorphous copolymers that retain the desirable electrical, chemical, and thermal properties of semicrystalline fluorinated plastics and also have such properties associated with amorphous materials as optical clarity, improved physical properties, and solubility in selected fluorinated solvents. 

The useful potential window of the equimolar AlCl3-NaCl melt extends from about 2.2 to 0 V vs. the A1(III)/A1 couple in NaCl(satd) melt. Plambeck [30] summarizes the physical properties of the equimolar (mp = 151 °C) and 63-37 mol% eutectic melts. Pyrex cells are satisfactory for use with the AlCl3-NaCl melt. Teflon has also been used in these melts, but it slowly decomposes. Experimentation with the alkali metal chloroaluminates requires the use of an inert-atmosphere glove box or a gas-tight cell. 

Physical properties were evaluated using standard DIN or ASTM specifications. The sealants were filled into Teflon molds to form homogeneous test pieces of comparable thickness. The specimens were then moisture cured and conditioned at 25 °C and 50% relative humidity for 14 days before mechanical property testing. The hardness of the cured sealant samples was measured by Shore A. Shelf life at 50 °C was determined for a maximum of 21 days. Tack-free times were determined by finger touch under ambient conditions. For adhesion testing the substrates were first wiped with either methyl ethyl ketone (aluminum, steel, glass, concrete, wood) or methanol (PVC, PMMA, ABS, polystyrene), then washed with detergent, rinsed with distilled water, and allowed to air dry prior to preparation of the test specimens. Specimens were cured for 14 days at ambient conditions. 

This improves temperature control of the material In the lines and avoids settling of reinforcing materials when they are used. All lines should be designed to be self-draining to simplify machine clean out. Smooth inside surfaced flexible hoses lined with Teflon are preferred where flexible lines are required. Where these lines are jacketed, It is preferred that the jackets be coupled to the suction side of the recirculating oil pumps to keep the oil pressures low. Should leakage occur between the jacket and the reactant streams, then It is more likely that the reactants will leak into the oil than visa versa. Oil contamination will adversely affect nylon RIM reaction speed and physical properties. Many manufacturers of RIM equipment recommend that all tanks, valves and fittings for nylon RIM machines be made of stainless steel. Mild steel and... 

Unlike inert fillers that have little effect on physical properties, reinforcing fillers such as carbon black and Teflon add to the mechanical properties of the polymer [6], Both of the polymers for rotating dynamic seals examined here contain carbon black as a reinforcing filler. Teflon is added to polyetheretherketone to increase the lubricity properties of the polymer. Ninety percent of carbon black is obtained through furnace black, which involves the combustion of thermal cracking of hydrocarbons [7], This reaction takes place at 1,200-1,400°C ... 

The RAI Research Corporation also offers a range of battery separators under the name of Permion (JL). These membranes are made by radiation grafting of a suitably active group onto an inert base film. The active groups include weak acids such as acrylic and substituted acrylic acid and stronger acidic groups such as sulfonated styrene. The base film can be Teflon R, polyethylene or polypropylene. They are thus not strictly perfluorinated membranes as is Nafion, but in chemical inertness and in many physical properties such as electrical conductivity and ion flux are useful as separators in batteries. 

Fluoropolymers. Melt processable fluoropolymers such as Teflon FEP, Tefzel ETFE, poly(vinylidene fluoride) (Kynar), and ethylene-chlorotrifluoroethylene copolymer (Halar) are suitable for wire insulation in special applications because they combine good physical properties with low flammability. They are used for instrumentation cable in process-control rooms, as well as for computer and aircraft wiring and in military applications. The... 

One way to conceptualize this phenomenon is to view the ponytails as short pieces of Teflon, which does not dissolve in any common solvent. As the ponytails become longer, some physical properties of the molecule approach those of Teflon. However, just as the miscibilities of fluorous liquid phases and organic liquid phases are highly temperature dependent, so are the solubilities of fluorous solids in fluorous or non-fluorous liquid phases. Hence, much higher solubilities can be achieved at elevated temperatures. This phenomenon can be used to conduct homogeneous reactions at elevated temperatures, with catalyst or reagent recovery by solid/liquid phase separation at lower temperatures. ... 

The best known fluorocarbon polymer is polytetrafluoroethylene (PTFE), commonly known as Teflon (DuPont). Other polymers containing fluorine are polytrifluorochloroethylene (PTFCE), polyvinylfluor-ide (PVF), and fluorinated ethylene propylene (FEP). Only PTFE will be discussed here since the others have rather inferior chemical and physical properties and are rarely used for implant fabrication. 

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