Polytetrafluoroethylene density

Fig. 11. Effect of polyolefin primers on bond strength of ethyl cyanoacrylate to plastics. All assemblies tested in accordance with ASTM D 4501 (block shear method). ETFE = ethylene tetrafluoroethylene copolymer LDPE = low-density polyethylene PFA = polyper-fluoroalkoxycthylene PBT = polybutylene terephthalate, PMP = polymethylpentene PPS = polyphenylene sulfide PP = polypropylene PS = polystyrene PTFE = polytetrafluoroethylene PU = polyurethane. From ref. [73].

Powdered Teflon for use in pyrots is covered by US Mil Spec MIL-P-48296IPA) (1 May 1974), Polytetrafluoroethylene (TFE) . Three classes of material are specified (1,2 3). The requirements are purity, 99.4% min infrared spectrum, peaks consistent with figure shown color, TFE shall be opaque and the color shall range from white to gray moisture, 0.05% max ash, 0.1% max mp, 337° 10°C packing density, Class 1 — 1.18 0.13g/cc, Class 2 - 1.25 0.02g/cc, Class 3- 1.14 0.09g/cc particle size by sieve analysis, Class 1 — 95 15 microns, Class 2 — 237 27 microns, Class 3 — 200 30 microns particle size distribution by sieve analysis, as specified in Table 1... 

Figure 4. Relative charge density persisting in various polymer compositions as a function of time after initial charging. The polytetrafluoroethylene system traps retain charge indefinitely whereas those in the polyethylene terephthalate decay...

ISO 7258 1984 Polytetrafluoroethylene (PTFE) tubing for aerospace applications -Methods for the determination of the density and relative density ISO 7313 1984 Aircraft - High temperature convoluted hose assemblies in polytetrafluoroethylene (PTFE)... 

The magnitude of n is related to the density of the substance and varies from 1.000 and 1.3333 for vacuum and water, to about 1.5 for many polymers and 2.5 for white pigment, titanium (IV) oxide (titanium dioxide). The value of n is often high for crystals and is dependent on the wavelength of the incident light and on the temperature. It is usually reported for the wavelength of the transparent sodium D line at 298 K. Typical refractive indices for polymers range from 1.35 for polytetrafluoroethylene to 1.67 for polyarylsulfone. 

The bulk (or volume) specific resistance p is one of the most useful electric properties that can be measured. Specific resistance is a physical quantity that may differ by more than 1023 in readily available materials. This unusually wide range of conductivity is basic to the wide use of electricity and many electric devices. Conductive materials, such as copper, have p values of about 10-6 ohm cm, while good insulators, such as polytetrafluoroethylene (PTFE) and low-density polyethylene (ldpe), have p values of about 1017 ohm cm. 

Nafion (17) is a perfluorinated polymer related to teflon (polytetrafluoroethylene). An electrode is conveniently coated by allowing an ethanolic solution of the polymer to evaporate. The film produced is stable, rather more so in fact than other polymer films, e.g. polyvinylpyridine (see Section 57.3.2.2). At the microscopic level the polymer separates into two phases, the bulk polymer and the lower density ionic cluster phase. Diffusion of ions can occur quite freely for example, the diffusion coefficient of Na+ in Nafion (MW 1200) is only slightly less than in water.44... 

A routine method for determining relative crystallinity based on the amorphous bands in the spectrum has proved more rapid and precise than the x-ray method. In practice, the ratio of the 778 cm-1 (12.85 ft) and 2367 cm-1 (4.22 ft) band intensities is measured. Use of a ratio eliminates the thickness measurement and increases precision to about 1% at 50% crystallinity and considerably better at higher levels. A density measurement and an infrared crystallinity determination when combined give an estimate of the fraction of microvoids which can occur in molded specimens of polytetrafluoroethylene. The density of a sample is predicted on the basis of its crystallinity as measured by the infrared method and the difference between this density and the actual density measured by displacement in water is a measure of the microvoid content. This determination is precise to about 0,2% voids by volume. By the use of confirmatory infrared measurements, it is possible to check the possibility that the presence of a substantial percentage of voids may have led to erroneous indications of the molecular weight in the standard specific gravity test discussed earlier. 

PS PSF PSU PTFE PU PUR PVA PVAL PVB PVC PVCA PVDA PVDC PVDF PVF PVOH SAN SB SBC SBR SMA SMC TA TDI TEFE TPA UF ULDPE UP UR VLDPE ZNC Polystyrene Polysulfone (also PSU) Polysulfone (also PSF) Polytetrafluoroethylene Polyurethane Polyurethane Poly(vinyl acetate) Poly(vinyl alcohol) poly(vinyl butyrate) Poly(vinyl chloride) Poly(vinyl chloride-acetate) Poly(vinylidene acetate) Poly(vinylidene chloride) Poly(vinylidene fluoride) Poly(vinyl fluoride) Poly(vinyl alcohol) Styrene-acrylonitrile copolymer Styrene-butadiene copolymer Styrene block copolymer Styrene butadiene rubber Styrene-maleic anhydride (also SMC) Styrene-maleic anhydride (also SMA) Terephthalic acid (also TPA) Toluene diisocyanate Ethylene-tetrafluoroethylene copolymer Terephthalic acid (also TA) Urea formaldehyde Ultralow-density polyethylene Unsaturated polyester resin Urethane Very low-density polyethylene Ziegler-Natta catalyst... 

As an example, Table 2 compares the results obtained using a smooth Cd cathode and a hydrophobicized Cd electrode prepared from powdered Cd, carbon, acetylene black A-437E, and polytetrafluoroethylene (PTFE) [31]. The current efficiency and current density increased for smooth Cd... 

FIG. 2 Bovine serum albumin adsorption to different polymer surfaces at 37°C in phosphate-buffered solution. The initial albumin concentration is 3 mg/ml. PVA poly(vinyl alcohol), PMMA poly(methyl methacrylate), PET polyethylene therephthalate), PP polypropylene, HDPE high-density polyethylene, PTFE polytetrafluoroethylene. (From Ref. 1.)... 

The following commercial polymeric substrates have been investigated low density polyethylene (PE, Dow Chemical Canada Inc.) polyimide (PI, DuPont Kapton H), polytetrafluoroethylene (PTFE, DuPont Teflon), polycarbonate (PC, Mobay Corp.) and surface-lubricated (with glycerol ester) polyvinylchloride (FVC, Canadian Occidental Petroleum Ltd). After plasma treatment, the samples were exposed to ambient atmosphere for 10 - 30 minutes while being transferred to the following... 

The dielectric constant of polytetrafluoroethylene is 2.1 and remains constant within the temperature range from -40 C to 250°C (-40°F to 482°F) within the frequency range from 5 Hz to 10 GHz. It changes somewhat, however, with density and factors that affect density. The dielectric constant was found not to change over 2 to 3 years of measurements [38]. 

The compns are based upon a copolymer of vinylidene fluoride and perfluoropropylene (Viton A) with polytetrafluoroethylene (Teflon) and various metals and oxidizers. A number of extrudable formulations are listed in Table 15 (Ref 57). The major advantages claimed for these proplnts are high density impulse, compatibility with highly energetic proplnt ingredients and resistance to high centrifugal forces... 

DSC curves can also be used to identify individual polymers in a polymer mixture. This is a rather unique capability of DSC or DTA. Figure 10.17 shows DSC curves of plastic waste. The individual melting peaks reveal the waste s polymer content. By comparing these curves with DSC curves of pure polymers, we can assign the melting peaks as those of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), Nylon-6, Nylon-66 and polytetrafluoroethylene (PIPE). 

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