Polytetrafluoroethylene test methods

ISO 8829 1990 Aerospace - Polytetrafluoroethylene (PTFE) hose assemblies - Test methods ISO 8913 1994 Aerospace - Lightweight polytetrafluoroethylene (PTFE) hose assemblies, classification 204 degrees C/21000 kPa - Procurement specification ISO 9528 1994 Aerospace - Standard-weight polytetrafluoroethylene (PTFE) hose assemblies, classification 204 degrees C/21000 kPa - Procurement specification ISO 9938 1994 Aerospace - Polytetrafluoroethylene (PTFE) hose assemblies, classification 204 degrees C/28 000 kPa- Procurement specification ISO 10502 1992 Aerospace - Hose assemblies in polytetrafluoroethylene (PTFE) for use up to 232 degrees C and 10 500 kPa - Procurement specification ISO 13000-1 1997 Plastics - Polytetrafluoroethylene (PTFE) semi-finished products -Part 1 Requirements and designation... 

Table 3.42 summarizes the standard test methods for characterization of polytetrafluoroethylene parts. These tests are often specified by the customer, and suppliers of parts are expected to meet them consistently. 

ASTM D6040-01 Standard Guide to Standard Test Methods for Unsintered Polytetrafluoroethylene (PTFE) Extruded Film or Tape... 

A4.1 The cup thermometer, which conforms also to the specifications for the low-range thermometer used in the Pensky-Martens flash tester. Test Method D 93, is frequently supplied by the thermometer manufacturer with a metal or polytetrafluoroethylene ferrule intended to fit the collar on... 

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].

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. 

In developing a method that requires filtration, adsorption of the analyte onto the filter must be taken into account. For dilute solutions of adriamycin, >95% is adsorbed to cellulose ester membranes and about 40% to polytetrafluoroethylene membranes [19]. For more concentrated solutions, as would be encountered in bulk formulation testing, filter ad-... 

Polytetrafluoroethylene parts have good wear properties, as seen from the data in Table 3.27. The resistance of unfilled PTFE to wear is less than that of filled compositions. Data from tests measuring wear rate are presented in Tables 3.28-3.30. They should be viewed with an understanding that none of the techniques represent an actual wear situation. In all three methods, a new surface is exposed to abrasion during the repeated motion of the abrading surface. 

Tests were then carried out on porous Teflon (polytetrafluoroethylene) (experiment 12, Table I). Commercially available membranes were procured, 10 microns in pore diameter. These pores were reduced in size by various combinations of application of heat and pressure to the membrane. A desalinization of 10 to 24% with a flux of 0.032 gallon per sq. foot per day was the best result obtained by this method. 

Our studies showed that the inner surface of the cardiovascular System was hydrophobic surface with Yc(Zis.)=29 dyne/cm. We could easily select polytetrafluoroethylene as the material with a smaller critical surface tension than 29 dyne/cm to make test materials. Figure-3 shows the surface properties of the inner surface of the cardiovascular system and polytetrafluoroethylene in relation to wetting properties viewed from Zisman s plots. How should we treat polytetrafluoroethylene to minimize the difference in wetting properties between the surface of polytetrafluoroethylene and the inner surface of the cardiovascular system. We tried to improve the surface properties of polytetrafluoroethylene by using the graft copolymerization method and expansion method. 

D 1457 Specification for PTFE Molding and Extrusion Materials D1675 Method of Testing Polytetrafluoroethylene Tubing D 1710 Specification for TFE Fluorocarbon Rod... 

Table 14.3 contains data that compares the results of plasma treatment and sodium etching for four fluo-ropolymers. Peel strengths of untreated and treated samples were measured by bonding them into T-peel specimen using the flexibilized epoxy adhesive Scotch-Weld 3553 (available from 3M Corp.). The laminates were cured for several hours at 70°C and peel tested at 12.5 cm/min pull rate. Polytetrafluoroethylene does not accept plasma treatment as well as PEA and FEP, as indicated by its relatively low peel strength. Sodium etching is the only effective method of modifying the surface of PTFE. 

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