Other plastic substrates

As mentioned earlier, other plastics such as poly(vinyl chloride), poly (ethylene terephthalate), polyacetals, nylons and polyimides do not present such a severe problem to the adhesives technologist as do fluorocarbon polymers or polyolefins. Nevertheless, in order to obtain very high joint strengths approaching the cohesive strength of the substrate, some form of surface pretreatment is often necessary. 

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Low angle shadowing requires that the specimen to be imaged is adsorbed to a smooth substrate. Consequently, the polyetherurethane materials were cast against the surface of a mercury puddle. This provided a surface sufficiently smooth to image individual macromolecules. The other plastic substrates were cast against glass microscope slides, and the carbon substrates vapor deposited onto the surface of freshly cleaved mica. 

Wide surface compatibility The high polarity of the base elastomer aids in developing adhesion to virtually all high polarity surfaces. Solvent-based products often develop good adhesion to low polarity surfaces such as polyolefins and other plastic substrates. 

Polyolefins, such as polyethylene, polypropylene and polymethyl pentene, as well as polyformaldehyde and polyether, may be more effectively treated with a sodium dichromate-sulfuric acid solution. This treatment oxidizes the surface, allowing better wetting by the adhesive. Flame treatment and corona discharge have also been used. Table 7.20 shows the relative joint strength of bonded polyethylene and other plastic substrates pretreated by these various methods. 

TABLE 7.20 Effect of Surface Treatments on Polyethylene and Other Plastic Substrates ... 

Classical antioxidants (AOs) like hindered phenols, Scheme 2, retard this transition metal promoted autoxidation process somewhat but give a very insufficient stabilization of powders or thin layers. However, by copolymerization with the so called "build-in" AOs, i.e. hindered phenols bearing 2-norbornene units like Ml - MS, the polymer stability could be improved. In addition, such compounds are very interesting AO s for the stabilization of other plastic substrates and rubbers [9]. AOs containing 2-norbornene units were also homo- and copolymerized to obtain polymeric stabilizers for plastics [10]. 

The adhesive must be compatible with the surfaces being bonded. Polystyrene foam is attacked by some solvent based adhesives. Also, plasticizers can migrate between adhesive and vinyls, or other plastic substrates. 

Other Materials. The amount of plastic substrates plated in 1991 for both decorative and electromagnetic shielding apphcations was estimated to be about 4.3-5.4 x 10 (13). 

Textiles, paper, and other flexible substrates such as fusible interlining, interlinking drapery and upholstered fabric, and carpets are examples of large volume applications. Another important market is with metals and other rigid materials. Included are plastics (pipes, tanks, screens, etc.) that can provide protective coatings using its variety of processing techniques. 

Although current processing temperatures for A1PO dielectrics remain above the threshold for plastic substrates, they are well within the thermal budget of several other substrates of interest for large-area applications. 

OLED on an Al-PET substrate. The device performance does not deteriorate after repeated bending, suggesting that there is no significant stress-induced change in the characteristics of the OLEDs fabricated on PET foil [71,82]. The results demonstrate the feasibility of fabricating flexible displays using a variety of plastic substrates including metal-laminated plastic foils, or a metal film sandwiched between two plastic foils. The flexible device structures enable a display to conform, bend, or roll into any shape and thus make possible other product concepts. 

Several other varieties of semiconducting electrodes have been produced by chemical vapor deposition, as noted earlier, including films of Ti02 on Ti [69], Ti02 on plastic substrates [71], and other materials, such as Fe203 and Sn02 films [11]. Most of these other electrodes have been tested as electrodes for use in photoelectrochemically induced water splitting and have not found conventional electroanalytical utility. 

THV can be readily bonded to itself and other plastics and elastomers. It does not require surface treatment, such as chemical etch or corona treatment, to attain good adhesion to other polymers, although in some cases tie-layers are necessary. For bonding THV to elastomers an adhesion promoter is compounded to the elastomer substrate.35... 

Most of the plastics discussed here could be used, not just in the manufacture of different materials and articles, but also as finishing materials in the form of coatings on other substrates. By using coatings, paper for example could be made impermeable to water or fat tin cans protected against corrosion kitchen articles and appliances made non-stick etc. Whereas films, containers and other plastic materials and articles are manufactured from polymerized materials, one often uses partly polymerized mixtures as coatings. These coating mixtures are then chemically crosslinked or thermally treated to bind them to the substrate material to make the finished product. This can cause complications for... 

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