Epoxies fluoropolymers

TABLE 1.57 EPOXY, FLUOROPOLYMER AND POLYETHYLENE RESINS-DURIRON (continued)... 

Some of the most important materials developed and used in large amounts during this time period were epoxies, fluoropolymers, polycarbonates, polyethers, polypropylene, and polyurethanes. Of course, the areas of free-radical, cationic and anionic polymerization grew concurrently. Perhaps the two most important developments in the area of synthesis were those of heterogeneous and stereoregular polymerization. 

In general, research on classes of materials is connected with that on materials with specific properties but includes somewhat more general research on composites, polyurethanes, epoxies, fluoropolymers, ferroelectric liquid crystals (especially those with fast switching times), polymer-polymer miscibility, double network elastomers, crystallization in polymers, polymeric Langmuir-Blodgett and other multilayer films, and polymer-stabilized synthetic membranes. 

When the relation between D and M is established, we can easily convert G(D) obtained by dynamic LLS into a differential molecular weight distribution, such as fw(M). We have successfully applied the above methods to various kinds of polymeric and colloidal systems, such as for Kevlar [15, 23], fluoropolymers (Tefzel Teflon) [12,30-35,52], epoxy [53-55],polyethylene [56,57], water-soluble polymers [18,50-51,58,59], copolymers [60-62], thermoplastics [63-65] and colloids [66-72]. Three of those applications are illustrated below. 

A wide variety of synthetic polymer resins can be used as water repeUents for concrete. These include acrylates, epoxies, chlorinated mbber, polyvinylbutyral, urethanes, elastomeric sUicones, and fluoropolymers. They are generaUy appUed from organic solvents or, in some cases, aqueous dispersions or latexes. Some have the disadvantage of inducing gloss and discoloration in the treated masonry. 

MAJOR POLYMER APPLICATIONS POM, PA, PC, PBT, epoxy, phenoxy, vinyl ester, fluoropolymers... 

Coatings are usually classified according to the resin binder. Thus, names such as acryhc, alkyd, epoxy, or chlorinated rubber are commonly used to identify coatings with those classes of binders. Other classes of coatings, as the fluoropolymers [10,11] have also become of common application e.g. in cod-coated steel. 

Though the majority of printed circuit boards (PCBs) at present are two-dimensional and made of glass-filled epoxy resins, increasing miniaturization has led to more PCBs being multi-layered with several copper circuits sandwiched between insulating layers. In these applications, because of the added stress due to thermal expansion, specialty materials such as polyamides and fluoropolymers have been increasingly used. 

Plastics find extensive use in several areas of fiber optic cables. Buffer tubes, usually extruded from high-performance plastics such as fluoropolymers, nylon, acetal resins, or polybutylene terephthalate (PBT) are used for sheathing optical fibers. A blend o PVC and ethylene vinyl acetate (EVA) polymer, such as Pantalast 1162 of Pantasote Incorporated, does not require a plasticizer, which helps the material maintain stability when in contact with water-proofing materials. PVC and elastomer blends, Carloy 6190 and 6178, of Cary Chemicals are also used for fiber optic applications (Stiffening rods for fiber optics are either pultruded epoxy and glass or steel. Around these is the outer jacketing, which is similar to conventional cable.)... 

Can we improve the scratch resistance of polymer-based materials Fortunately, the answer is yes. One way is to apply a low concentration additive to a given polymer-based material. This is much easier said than done— but possible (72,73). In Figure 19 we see the residual depth Rh in a commercial epoxy as a function of concentration of an added fluoropolymer for various forces applied by... 

Figure 22-2. Onsite testing panel of the Last Judgment mosaic after 2 years of outdoors exposure. Left (6) is the sol gel/functionalized fluoropolymer coating combination. Right (1) is an epoxy polymer exhibiting delamination.

Fluoropolymers. There are no known adhesives for fluoropolymers that give bonds of adequate strength without pretreatment. Simple, low-quality bonds can be obtained with contact adhesives. After chemical pretreatment, for example, with a solution of an alkali metal naphthalenide in THF, polyfluorocarbons can be bonded with high strength by using epoxy and polyurethane adhesives. 

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