Surface preparation nylon

There are several features to note about Figure 4.7. While water will bead on a surface prepared with PTFE or an FA, it will wet a nylon-6,6 surface. For the case of hexadecane, botlr PTFE and FA surfaces will show appreciable contact angles, while a nylon-6,6 surface will be wetted completely (0 = 0). This is the reason that oily soils are relatively difficult to remove from materials made from nylon-6,6. The surface of a material prepared with a FA using perfluoroalkyl chains often has a lower surface tension than PTFE. For comparison, the surface tensions of nylon-6,6, PTFE " and FAs are estimated to be about 46, 24, and 10-20 mN/m, respectively. 

One surface preparation method that is unique for composites employs a peel or tear ply.77 Utilization of the peel ply is illustrated in Fig. 16.5. With this technique, a closely woven nylon or polyester cloth is incorporated as the outer layer of the composite during its production layup. This outer ply is then torn or peeled away just before bonding. The tearing or peeling process fractures the resin matrix coating and exposes a clean, fresh, roughened surface for the adhesive. This method is fast and eliminates the need for solvent cleaning and mechanical abrasion. 

As a general rule, nylon surfaces demand great care in preparation for bonding. 

The variety of assays reported here displays the great versatility of luminescent detection systems. As already described, in all luminescent systems the main advantages are the high sensitivity and specificity, which reduce to the minimum the sample treatment, and the ease of use of the reagents and the luminometer. Immobilized systems greatly reduce the cost per assay on the other hand, their preparation requires expertise, especially in the surface activation step on nylon tubes. 

The surface tensions of materials prepared with are some of the lowest attainable with the reagents commonly available, which is why many carpet and textile repellents are based on the chemistry of perfluoroalkyl chains. For example, a nylon-6,6 carpet would be wetted by oily soils, which, according to Eq. (4), would be difficult to remove. The presence of a FA coating on die fiber lowers its surface tension and repels the oil contaminant. In general, a liquid dial has a high surface tension will not wet a solid with low surface tension (e.g., water on PTFE). The converse is also true. A low-surface-tension liquid will wet a high surface tension solid (e.g., hexadecane on nylon-6,6). 

Some specialty nylons are actually prepared by the technique of interfacial polymerization. In the laboratory, small quantities (1 to 100 g) can be made in a blender (similar to a kitchen blende but explosion proof), where the rapid agitation increases the surface area of the mixture, increasing the rate and efficiency of the reaction. 

In addition, two end-tethered delaminated hybrid systems prepared by in-situ polymerization - (a) Poly( -caprolactone)-montmorillonite (PCLC) and (b) nylon-6-montmorillonite (NCH) - wherein the polymer chains are end-tethered to the silicate surface via cationic surfactants [54] (Fig. 20), were also studied. 

Fig. 4.15 Solvent-exclusion contribution to image contrast is demonstrated with scanning force data acquired on a co-block-polyethylene glycolpoly amide (Nylon-12) surface (PEBAX 1,074), prepared by melting/resolidification. (a) Topographic image in water, methoxy tip termination (15 x 15 pm2) (b) friction LFM image in water, methoxy tip termination (15 x 15 pm2) (c) topographic image in water, amide tip termination (7.5 x 7.5 pm2), (d) friction image in water, amide tip termination (7.5 x 7.5 pm2). (Reprinted with permission from [32]. Copyright 1996. American Chemical Society.)...

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