Vespel

Du Pont produces this polymer under the trade names of Kapton, Pyrafin, Vespel, and Pyre-ML. The trade names refer to polyimides used for film, semiconductor coatings, mol ding applications, and wire enamel, respectively. They have exceUent thermal, electrical, and physical properties. 

Some typical properties of a fabricated solid grade (Vespel-Du Pont) are given in Table 18.13 together with some data on a graphite-loaded variety and a commercial polyamide-imide (Torlon 2000—Amoco). 

The limited tractability of the polymer makes processing in conventional plastics form very difficult. Nevertheless the materials have been used in the manufacture of seals, gaskets and piston rings (Vespel-Du Pont) and also as the binder resin for diamond grinding wheels. 

Property Units ASTM test Vespel, unfilled Vespel, 15% graphite filled Torlon 2000, unfilled... 

SEAT 81C-TEFLON, KEL-F, ORVESPEL 83C-BUNA-N 81S-TEFLON,KEL-F, OR VESPEL 83S-BUNA-N... 

Teflon, Kel-F, Vespel or Buna-N 316 stainless steel 17-4 stainless steel or 316 SS 316 stainless steel 316 stainless steel... 

Figure 9.9 Schesatic diagrans of flow-through cell. A, and solvent elimination interfar B, for SFC/FTIR. For A (1) polished stainless steel lig..v.pipe (2) zinc selenide window (3) PTFE spacer (4) viton rubber o-ring (5) graphitized Vespel nicroferrule (6) deactivated fused-silica capillary tubing (7) bolt with Allen nut (8) stainless steel end-fitting and (9) stainless steel body of flow cell.

Fig. 3.14. Relative linear thermal expansion coefficient of (1) Invar, (2) Pyrex, (3) W, (4) Ni, (5) Cuo.7Ni03, (6) stainless steel, (7) Cu, (8) brass, (9) Al, (10) Torlon, (11) soft solder, (12) Vespel SP-22, (13) Hg, (14) In, (15) Araldite, (16) Stycast 1266, (17) PMMA, (18) Nylon, (19) Teflon [60]. Some additional data are Ag between (8) and (9) Stycast 2850 GT slightly larger than (9). The integral contraction between 300 and 4K is 103AL/L = 11.5, 4.2, 6.3 and 5.7 for Stycast 1266, Stycast 2850 GT, Vespel SP-22 and solders...

Fig. 13.3. Relative thermal expansion of Torlon compared with those of PMMA [55], Vespel SP22...

Actymid, Aurum, Compimide, Cuming C-Stock, Duratron, Imidex, Kapton, Kerimid, Kinel, Meldin, Neopreg, Nolimid, Nomex, Sintimid, Upilex, Upimol, Vespel, Willmid. 

Multinuclear NMR spectroscopy is being used increasingly to study catalytic reactions. In order for such studies to be possible, all contact betv een the sample solutions and the metal part of the cell body has to be avoided because of possible catalytic effects. All materials in contact vith the sample solution have to be chemically inert and nonmetallic quartz, glass, PTFE, Vespel (polyimide polymer, Dupont de Nemours), PCTFE (poly-chlorotrifluoroethylene), Viton seals, etc. 

Figure 2.11 High pressure NMR probe using a toroid detector (from Ref [29]). SP-1 Vespel...

Many of the bisbenzocyclobutene polymers are relatively unaffected by organic solvents and aqueous media. In Table 11 are shown some of the results which were obtained in a solvent pick-up study carried out on the bisbenzocyclobutene polyester 40 [2]. Of all of the solvents, only trichloroethylene and methyl ethyl ketone were absorbed to any significant extent at 70 °C over the four-week course of the experiment. None of the polymer samples dissolved in the solvents that were tested and only a slight swelling was observed with those liquids which were significantly absorbed. The small effect of aqueous sodium hydroxide on the bisbenzocyclobutene polyester is deserving of note since a control sample of a commercial polyimide (Vespel ) dissolved completely in two days under the conditions of this test. 

Fig. 10. Radiation effects on the flexural strength on pure and glass-fabric filled poly-imides irradiated at 4.9 K. (O) Spaulrad ( ) Norplex (A) Vespel...

A1 MAS NMR spectra were measured at 104.26 MHz using powerful 0.6 ps radiofrequency pulses with a 0.2 s recycle delay. Samples were spun at 3.4 kHz in an aluminium-free probehead and Vespel rotors. Chemical shifts are quoted in ppm from external A1(H20)63+. 10000 transients were acquired for each spectrum. 

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