Epoxy phenolic molding

For many years prior to the development of high-temperature thermoplastics and thermosets, such as the polyimides. polysulfones, and epoxies, phenolic molding material dominated the high temperature-resistant market. This emphasizes their ability to resist temperature degradation in the 400-500°F (204-260 C) range. Because phenolics were found to possess excellent ablative properties, it has been reported that both the American and Soviet space efforts used them in combination with certain other... 

Single-package epoxy-phenolic molding materials (14) usually utilize a solid epoxidlzed novolak and a phenolic novolak resin in a formulation such as that shown below ... 

In addition to electrical uses, epoxy casting resins are utilized in the manufacture of tools, ie, contact and match molds, stretch blocks, vacuum-forrning tools, and foundry patterns, as weU as bench tops and kitchen sinks. Systems consist of a gel-coat formulation designed to form a thin coating over the pattern which provides a perfect reproduction of the pattern detail. This is backed by a heavily filled epoxy system which also incorporates fiber reinforcements to give the tool its strength. For moderate temperature service, a Hquid bisphenol A epoxy resin with an aHphatic amine is used. For higher temperature service, a modified system based on an epoxy phenol novolak and an aromatic diamine hardener may be used. 

Common to all reinforced plastics are two ingredients, resin and reinforcement. Resin is an oiganic material, usually of high molecular weight, that can be molded and set into a final shape. Resins are of two basic types. Thermoplastic resins soften upon heating, are shaped in a mold, and retain that shape when cooled. Common examples are nylon, polyethylene, polypropylene, and polycarbonate. Thermosetting resins are placed in a mold and cured by the use of a catalyst, heat, or both, until they harden in the shape of the mold. Common examples are polyester, vinyl ester, epoxies, phenolics, and p olyure thanes. 

TEDLAR films are supplied with different surface characteristics. A (one side adherable) and B (both sides adherable) surfaces are used with adhesives for bonding to a wide variety of substrates. These surfaces can be bonded with a variety of adhesives, including acrylics, polyesters, epoxies, elastomeric adhesives, and pressure-sensitive mastics. The S surface has excellent antistick properties and is being used as a mold-release film for parts made from epoxies, phenolics, elastomers, and other polymeric materials.94... 

The base-catalyzed reaction of an epoxy resin with the phenolic resin produces a cross-linked polyether structure that is resistant to chemicals and heat and is a good moisture vapor barrier. Since the curing mechanism does not produce byproducts, thick sections may be obtained without voids and low shrinkage. Applications that employ the advantages of epoxy-phenolic formulations Include molding materials, laminates, coatings, and adhesives. 

RTM is compatible with a variety of thermosetting polymers including polyester, vinyl ester, epoxy, phenolic, modified acrylic, and hybrid polyester-urethane. A convenient typical viscosity of thermoset precursors is in the range of 0.2-0.6 Pa s. The RTM process has the following advantages (i) emissions are lower than in open-mold processes such as spray-up or hand lay-up (ii) it can produce parts faster, as much as 5-20 times faster than open-mold techniques (iii) the mold surface can produce a high quality finish (iv) complex mold shapes can be achieved and... 

Reinforced plastics are composites in which a resin is combined with a reinforcing agent to improve one or more properties of the resin matrix. The resin may be either thermosetting or thermoplastic. Typical thermosetting resins used in RPs include unsaturated polyester, epoxy, phenolic, melamine, silicone, alkyd, and diallyl phthalate. In the field of reinforced thermoplastics (RTFs), virtually every type of thermoplastic material can be, and has been, reinforced and commercially molded. The more popular grades include nylon, polystyrene, polycarbonate, polyporpylene, polyethylene, acetal, PVC, ABS, styrene-acrylonitrile, polysulfone, polyphenylene sulfide, and thermoplastic polyesters. 

Notable among the thermoplastic materials are polyethylene, polypropylene, polyvinyl chloride, the styrene synthetic rubber blends, the acrylics, and the fluorocarbons. Notable among the thermosetting reinforced materials are the polyesters, epoxy, and the furan resins as custom-made reinforced materials, and the phenolic and epoxy resins molded, filament-wound, and/or extruded with reinforcement. AU these materials are available as piping, sheet stock, and miscellaneous molded and fabricated items. These materials, particularly polyvinyl chloride, polypropylene, and reinforced polyesters, are now being used extensively for ventilating ductwork in handling corrosive fumes. They have proved to be economically improved over metals such as stainless steel, lead. 

The most important resin types used in production of curable molding compounds are phenolic, urea, melamine, unsaturated polyester, epoxide and diallyl phthalate resins. Curable molding compounds built up with these bonding agents are described in DIN 7708" (Phenoplasts and Aminoplasts), DIN 16911 and 169132 (Polyester Molding Compounds and Polyester Resin Mats), and DIN 16912 (Epoxy resin Molding Compounds). There is as yet no standard for diallyl phthalate masses, for the test method see ISO 1385 - 1.02.1977. 

CAS 21645-51-2 EINECS/ELINCS 244-492-7 Uses Filler, flame retardant, smoke suppressant for spray-up or hand lay-up FRP applies., filament winding, panel prod., resin injection, SMC/ BMC, acrylic sheet rigidizing, cast polyester parts, epoxy encapsulat-ing/potting, powd. coatings, epoxy elec, laminates, phenolic molding, flexible PU foams... 

Uses Filler, additive for plastics, coating, friction, refractory, ceramic, construction, elastomer, sealant, and adhesive applies., for nylon, phenolic molding compds., epoxy, polyester, PU/polyurea Featiffes Cost-effective functional filler surf, modifications can improve processing, bonding between resin and filler, mech. and phys. props., material handling and warehousing, etc. 

Cold molding Compression molding Epoxy, phenolic, polyester (thermoset), polyurethane (thermoset)... 

Another class of epoxy resins is the novolacs, particularly the epoxy cresols and the epoxy phenol novolacs. These are produced by reacting a novolac resin, usually formed by the reaction of o-aesol or phenol and formaldehyde with epichlorohydrin. These highly functional materials are particularly recommended for transfer molding powders, electrical laminates, and parts in which superior thermal properties, high resistance to solvents and chemicals, and high reactivity with hardeners are needed. 

Early resin materials used in mold compound formulations were sihcones, phenolic resins, and bisphenol-A or bisphenol-F epoxies. Because of shortcomings in performance, these materials have been displaced by epoxy phenol or cresol novalac resins (ECN resins) and by the biphenyl- and tris(triphenylmethane)-type epoxies (70) (Fig. 20). The high cross-link density of ECN-based materials results in low moisture absorption rate and higher thermal stabihty than... 

Non-silicone for thermosets Synthetic wax-based product For injection molding, encapsulating, potting For epoxy, polyester and phenolic molding Maximum operating temperature 450F... 

A list of materials regarded as high-performance polymers (Table 17.10) overlaps the list of Table 17.9 to some extent, but also includes thermosets such as epoxy, phenolic, and silicone molding resins. As with most molded plastics, high-tanperature performance is enhanced by reinforcement with glass, boron, or carbon or aramid fibers. The thermosets are seldom used without reinforcement. Several are inclnded in Figures 17.6 and 17.7. 

The thermoplastic or thermoset nature of the resin in the colorant—resin matrix is also important. For thermoplastics, the polymerisation reaction is completed, the materials are processed at or close to their melting points, and scrap may be reground and remolded, eg, polyethylene, propjiene, poly(vinyl chloride), acetal resins (qv), acryhcs, ABS, nylons, ceUulosics, and polystyrene (see Olefin polymers Vinyl polymers Acrylic ester polymers Polyamides Cellulose ESTERS Styrene polymers). In the case of thermoset resins, the chemical reaction is only partially complete when the colorants are added and is concluded when the resin is molded. The result is a nonmeltable cross-linked resin that caimot be reworked, eg, epoxy resins (qv), urea—formaldehyde, melamine—formaldehyde, phenoHcs, and thermoset polyesters (qv) (see Amino resins and plastics Phenolic resins). 

Even though most of the literature on processing specifically identifies or refers to thermoplastics (TPs) as in this book, some thermosets (TSs) are used (TS polyesters, phenolics, epoxy, etc.). The TPs reach maximum heat prior to entering cool mold cavities, whereas the TSs reach their maximum temperature in hot molds (Fig. 6-3). 

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