Bonded Film Components

Acrylics Tungsten diselenide Isopropyl alcohol Toluene 

Organic Heat-Cured Inorganic Amyl acetate 

Sodium borate Titanates Inorganic ceramic Boric oxide Silica Alumina Calcium fluoride Metal Silver Nickel Gold Tantalum Indium/lead  

However, there can be little doubt that many of the commercial formulations are still based on the research work carried out between 1950 and 1980, and the work published in that period will therefore be still relevant. 

Hopkins and Campbell described a film based on polyphenylenesulphide (PPS). This is a very strong and inert poiymer with good thermal stability to over 300°C after curing. It can be slush or melt-coated onto metal surfaces, but gives a 

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Apart from the three major components of the bonded film, the binder, the molybdenum disulphide, and the solvent or dispersant, many other substances may be incorporated, and several have already been mentioned. 

A number of different metals have been used in powder form as additives to bonded molybdenum disulphide films. They include gold, silver, nickel and tantalum, and it has been suggested that they improve film life by helping to facilitate readhesion of lubricant debris to the substrate. Many other components have been added to bonded films as corrosion inhibitors, anti-oxidants, dispersion stabilisers and biocides, and many different solvents have been used. There is therefore an almost infinite variety of possible formulations, and several hundred have been produced commercially. 

The initial properties of bonded films as applied vary considerably depending on the type of binder, the ratio of binder to molybdenum disulphide and other components, the nature of the drying or curing process, and the way in which the film was applied, in particular there is a wide variation in hardness from very soft (silicones and alkyds) to very hard (metals and ceramics), and this has important implications for the way in which a film is used and even the purpose for which it is used. 

Figure 5. Alditol acetates as resolved on the trlfluoro-propylnethyl silicone DB-210. Split Injection, Isothermal at 220°C 30 m x 0.25 nm column coated with a bonded 0.25 pm film. Components 1, rhamnltol 2, fucltol 3, rlbl-tol 4, arablnltol 5, mannitol 6, galacltol 7, glucl-tol 8, Inositol.

Figure 6. Free underivacized steroids as resolved on the 50% phenyl-polymethylslloxane DB-17. Split injection at 260 isothermal 30m X 0.2Smm column coated with a 0.15 m bonded film of DB-17, hydrogen carrier at 44cm/sec. Components 1, coprostane (5-B-cholestane) 2, 5-y5-androsterone 3, 5-01-cholestane 4, androsterone 5, eplandrosterone (trans-androsterone) 6, 17-estradiol 7, -estradiol 8, estrone 9, progesterone 10, cholesterol 11, estriol 12, stigmasterol.

Figure 7. Methyl esters of unsaturated fatty acids as resolved on the 25%-cyanopropyl-25%-phenyl methyl siloxane DB-225. Split Injection to a 30m x 0.25mm column coated with a 0.25 m bonded film, hydrogen carrier at 46cm/sec, isothermal at 200 °C. Components 1, 14 1 methyl myristoleate 2, 16 1 trans methyl palmite-laidate 3, 16 1 cis methyl palmitoleate 4, 18 1 trans methyl elaidate 5, 18 1 cis methyl oleate 6, 18 2 trans methyl linolea-laidate 7, 18 2 cis methyl linoleate 8, 18 3 methyl linoleate ...

Figure 8> Dimethyl esters of the dlcarboxlllc adds as resolved on the dlcyanoallyl silicone DB-275. Split Injection to a 30 m x 0.25 mm column with a 0.15 pm bonded film of DB-275. Hydrogen carrier at 40 cm/sec 110 C 1 min, 4 /mln to 150. Components as shown.

The prime function of adhesives is to mechanically attach or bond devices, components, heat sinks, wire, connectors, and other parts onto a circuit board or an interconnect substrate. Adhesives are also used as pastes or films to attach lids in sealing cavity packages and as dielectric films in fabricating multilayer interconnect substrates. The most important consideration in obtaining a reliable adhesive bond is the ability of the adhesive to flow and wet the surfaces. For a reliable bond, strong adhesion to both surfaces and strong cohesion within the adhesive are necessary. 

In spread coating (laquering), solutions of film-forming polymers are applied and the solvent allowed to evaporate. Metallic and nonmetallic components and films of cellulose or aluminum are lacquered. Lacquered cellulose films are less permeable to water vapor, but poly(ethylene)-bonded films compete with these on the market (Section 12.2.6). Paints and lacquers... 

Apart from their use as tie layers in coextension, the modified polymers can find other adhesive applications such as improving adhesion of extrusion coatings, thermal lamination interplies, and as dispersions or powder coatings. As coatings, the modified polymers applied to metal surfaces can act as an adhesive layer to bond plastic components. A particularly useful version is to prepare a coextended film of a non-modified base polymer such as polyethylene or polypropylene, forming the bnlk of the structure, and apply a thin layer of the modified polymer to one or both external surfaces. This steucture may now be used to thermally bond to a metal substrate. 

In a detailed analysis, the TPD curve for the sample fired at 350 °C was separated into five peak components using a Gaussian-type waveform (Figure 23). Component (a) is presumably due to physisorbed H2O (mere adsorption of H2O) on the surface of the Zr02 thin films. This was confirmed experimentally as discussed in the next subsection. Component (e) can be attributed to the desorption of H2O through nanopores of the crystallized Zr02 thin film. Component (b) can be ascribed to the desorption of H2O and/ or chemisorbed Zr-OH bonds at the surface area. For components (c) and (d), H2O desorption may have occurred because of the following reaction (s Zr-OH + HO-Zr = —> = Zr-O-Zr = + H2O). 

Suppose next that extensibility of the film is taken into account. If the bonded film supports a uniform equi-biaxial mismatch stress <7 then the elastic energy density per unit area of interface far ahead of the line of separation compared to h is W+ = a hf/Mf = t /h Mf. For points far behind the separation point, the nonzero stress components are Oxx = q/h and ayy = + (1 — these values are based on the constraint that... 

As a tme thermoplastic, FEP copolymer can be melt-processed by extmsion and compression, injection, and blow molding. Films can be heat-bonded and sealed, vacuum-formed, and laminated to various substrates. Chemical inertness and corrosion resistance make FEP highly suitable for chemical services its dielectric and insulating properties favor it for electrical and electronic service and its low frictional properties, mechanical toughness, thermal stabiUty, and nonstick quaUty make it highly suitable for bearings and seals, high temperature components, and nonstick surfaces. 

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