Nylon columns

Woelm nylon column DCC-5 was used, giving a packed column of silica gel 66-67 cm. high and 32 mm. in diameter. 

Marine polymeric DOC has often been given the special name of Gelbstoff (Ger., yellow material, after the name given it by Kalle cf. his review of the subject in 1966) it was first recognized in the 1930s as the basis for the color of seawater. On the basis of a cursory similarity to the humic substances of soils and freshwaters, it has been called marine humus, although it may actually bear practically no molecular resemblance to the other polymers of this type. In an early comparison of the two classes of material, Sieburth and Jensen (1968) concentrated both marine and freshwater Gelbstoff on nylon columns, eluted them with NaOH,... 

It should be briefly mentioned that glycosidases have also been used whilst immobilised on a powdered nylon column [11] and a non-ionic Amberlite resin [31] so that the enzyme can be recycled for several experiments. 

Caprolactam Extraction. A high degree of purification is necessary for fiber-grade caprolactam, the monomer for nylon-6 (see Polyamides). Cmde aqueous caprolactam is purified by solvent extractions using aromatic hydrocarbons such as toluene as the solvent (233). Many of the well-known types of column contactors have been used a detailed description of the process is available (234). 

CycIohexanediamine s commercial origin is its presence as a minor 0.1 <1% coproduct of hexamethylenediamine [124-09-4] produced by hydrogenation of adiponittile [111-69-3]. Fractional distillation by up to four columns in a series is routine commercial practice to purify nylon grade acychc diamine the cmde cycloahphatic diamine requires further refining before use as a specification intermediate. 

The XK column system is a medium-pressure jacketed glass column system designed for operating pressures up to 5 bar (0.5 MPa). Column dead volumes are less than 0.1% of the total column volume. Wetted materials include EPDM, TEFZEL, superpolyoxymethylene, and flurorubber. Columns use nylon nets of 10-)Lim mesh size and may be used with most SEC media with particle diameters >20 /xm. Columns are intended for use with aqueous solutions and... 

FIGURE 6.19 Polyamide. Column Shodex GPC HFIP-80S + HFIP-803, 8 mm i.d. x 300 mm x 2. Eluent S mM CFaCOONa/HFIP. Flow rate 1.0 mL/min. Detector Shodex Rl. Column temp. 40°C. Sample 0.05%. SOO /iL. Poly(hexamethylene adipamide) (Nylon 66). 

As a final example of column durability and solvent resistance in small pore gels we were able to resolve nylon 6 oligomers using a methanol mobile phase and 205-nm UV detection as shown in Figure 13.29. In fact, polar solvents such as acetone, acetonitrile, methanol, and 2-propanol, are used routinely as needed with no ill effects. 

Figure 12-10. The Inventa-Fisher process for producing nylon 6 from caprolactam (1) Melting station, (2,3) polymerization reactors, (4) extruder, (5) Intermediate vessel, (6) extraction column, (7,8) extraction columns, (9) cooling silo.

Removal of solvent from the extracts leaves a residue that is purified by dry-column chromatography.2 The residue is dissolved in 40 ml. of acetone in a 300-ml., round-bottomed flask, 30 g. of silica gel (Note 8) is added, and the acetone is removed with a rotary evaporator. The resulting solid mixture is placed on top of 360 g. of dry silica gel (Note 8) packed in flexible nylon tubing (Note 9), and the column is developed with 420 ml. of 10 1 (vjv) benzene-acetone. Approximately 150 ml. of solvent drips from the bottom of the column toward the end of development, and this eluent is collected in 25-ml. fractions and checked for product by thin layer chromatography (Note 10). The column itself is then cut into 2-cm. sections, the silica gel in each section is eluted with three 25-ml. portions of ethyl acetate, and the eluent from each section is analyzed by thin-layer chromatography (Note 10). Combination of all the product-containing fractions yields 1.2-1.5g. (40-47%) of the benzylated compound as an oil, n 1.6083 (Notes 11 and 12). 

In die case of nylon-6,6 waste recycled by ammonolysis, nylon is treated with ammonia in die presence of a phosphate catalyst. Reaction occurs at 330°C and 7 MPa. Distillation of die reaction mixture produces ammonia which is recycled and three fractions containing (a) caprolactam, (b) HMDA and aminocaproni-trile, and (c) adiponitrile. Aminocapronitrile and adiponitrile are hydrogenated to yield pure HMDA, and die caprolactam is eidier converted to aminocapronitrile by further ammonolysis or distilled to produce pure caprolactam. The HMDA produced by this process is extremely pure (>99.8).1 The main impurities are aminomediylcyclopentylaniiiie and tetrahydroazepine, which are expected to be removed more effectively in the larger distillation columns employed in the larger plants. 

Hie hydrolytic depolymerization of nylon-6 was followed by gel permeation chromatography (GPC), viscometry, and gravimetry. GPC determinations were performed on a Waters 150C chromatography system using benzyl alcohol as die eluant, two Plgel 10-p.m crosslinked polystyrene columns, and a differential refractometer detector. The flow rate was 1 mL/min. The concentration of the polymer solutions was 0.5 wt% and dissolution was accomplished at 130°C. 

In this section a short description of a comparison between experimental and simulation results for heat transfer is illustrated (Nijemeisland and Dixon, 2001). The experimental set-up used was a single packed tube with a heated wall as shown in Fig. 8. The packed bed consisted of 44 one-inch diameter spheres. The column (single tube) in which they were packed had an inner diameter of two inches. The column consisted of two main parts. The bottom part was an unheated 6-inch packed nylon tube as a calming section, and the top part of the column was an 18-inch steam-heated section maintained at a constant wall temperature. The 44-sphere packed bed fills the entire calming section and part of the heated section leaving room above the packing for the thermocouple cross (Fig. 8) for measuring gas temperatures above the bed. 

Glass columns for separation by gravity flow glass, metal or nylon tubing for pressurized systems fraction collector, detector and recorder. 

The reasons are pretty simple, if not obvious. How re you going to see where to make the cuts if you run colorless samples Even though nylon tubing is transparent to UV light, and theoretically you can see the compounds under UV, many eluents absorb in the UV, and the whole column would just look dark. Then you d probably get into trouble guessing where to make the cuts in the tubing to get the compounds separated. Just stick to colored compounds. And don t say I didn t warn you. 

Columns for gel permeation chromatography must have both a minimal dead space volume at the outlet, to prevent broadening of the zones developed during the separation, and a suitable bed support, e.g. nylon mesh, which will retain the gel without becoming blocked. The length of the column affects the resolution,... 

Medley (M4) working in vacuum also found that mercury became positively charged relative to nylon, mica, and Alkathene6 film. He obtained the contact by bringing a column of mercury up against a film of the other material, the back of which was covered with a stationary film of mercury connected to an electrometer, which measured the charge after the contact... 

Groom and Luong [103] designed a flow-through biosensor for cyanide consisting of a column packed with rhodanase immobilized on a preactivated nylon membrane attached to the surface of a hydrogen peroxide... 

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