Polymer epoxy-metal

Dispersion forces57 , which result from temporary variations in the distribution of electron density in atoms, can account for up to 90 per cent58 of the adhesion forces between non-polar polymers and metal substrates (bond energy 0.5-5 Kcal/ mole)50 . However, for the adhesion of epoxy resins and other polar polymers to metals, dispersion forces are of secondary importance when compared to the electromagnetic and mechanical interactions discussed above. 

For webs, the substrate electrode is usually a vapor-deposited, semitransparent metal layer (Ritchie and Fenn, 1987 Chen, 1993). Al, Ni, and Cr are commonly used. The use of semi-transparent electrodes permits the use of rear exposures for erase purposes. In the case of drums, the metal cylinder serves as the electrode. Usually, a thin, less than 1 pm, blocking layer is interposed between the electrode and the photoreceptor to prevent charge injection. This layer must not be so thick that a residual potential builds up during cycling. Many insulating polymers have been used acrylic polymers, epoxy resins, polyamides, polyesters, polyphosphazenes, polysiloxanes, polyurethanes, vinyl polymers, etc. 

HDPE, composite materials such as epoxy-glass fiber and epoxy-carbon fiber, and laminate structures such as polymer films on bulk metal substrates. Thin-conductive film heaters were made of electrically conductive paints, electrically conductive polymer films, metal foils (stainless-steel, copper, titanium, and titanium alloys), and thin metal films sputtered on a ceramics or glass. The samples dimensions varied from a few centimeters to 5m. 

Lamothe RM, Nunes J, Evaluation of fixturing for compression testing of metal matrix and polymer/epoxy composites, Chait R, Papirno R eds., Compression Testing of Homogeneous Materials and Composites, ASTM STP 808, American Society for Testing and Materials 241-253, 1983. 

The newest oxidizer to appear in significant use in pyrotechnics, anunonium perchlorate (AP), has found considerable use in modem solid-fuel rocket propellants and in the firewoiks industry. The Space Shuttle alone uses approximately 2 million pounds of solid fuel per launch the mixture is 70% ammonium perchlorate, 16% almninum metal, and 14% organic polymer/epoxy, with a trace of iron oxide catalyst that can be varied to modify the bum rate. The aluminum powder is a surprising ingredient to find in a propellant, since it generates solid rather than gaseous reaction products, but its substantial heat output as a fuel and its excellent thermal conductivity both contribute to an enhancement of the bum rate of this propellant formulation. 

Sufficient titanate leads to a fully hardened polymer. Using only enough titanate to react with free hydroxyls, the resin may subsequently be cured at lower cost with conventional cross-linking agents. The titanated epoxy resin has a low power factor, which is important in electrical appHcations, eg, potting components and insulation (see Embedding). Titanates improve adhesion of metals to epoxies. 

A variety of materials has been proposed to modify the properties of asphaltic binders to enhance the properties of the mix (112), including fillers and fibers to reinforce the asphalt—aggregate mixture (114), sulfur to strengthen or harden the binder (115,116), polymers (98,117—121), mbber (122), epoxy—resin composites (123), antistripping agents (124), metal complexes (125,126), and lime (127,128). AH of these additives serve to improve the properties of the binder and, ultimately, the properties of the asphalt—aggregate mix. 

Most successful composites combine the stiffness and hardness of a ceramic (like glass, carbon, or tungsten carbide) with the ductility and toughness of a polymer (like epoxy) or a metal (like cobalt). You will find all you need to know about them in Chapter 25. 

There have been other approaches to obtaining rubber/metal adhesion besides primers or additives consisting of phenolics or epoxies plus halogenated elastomers. For example, carboxylated polymers (olefins and diolefins copolymerized with acrylic acid monomers) have shown excellent adhesion to metals. Very little carboxyl is necessary, and polymers with carboxyl contents as low as 0.1% show good adhesion when laminated to bare steel. When these materials possess... 

Historically, polymer-matrix composite materials such as boron-epoxy and graphite-epoxy first found favor in applications, followed by metal-matrix materials such as boron-aluminum. Ceramic-matrix and carbon-matrix materials are still under development at this writing, but carbon-matrix materials have been applied in the relatively limited areas of reentry vehicle nosetips, rocket nozzles, and the Space Shuttle since the early 1970s. 

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