Epoxy Casting resin

These transformers may be PVC taped, thermoplastic (polypropylene) moulded, fibreglass taped, polyester resin cast or epoxy resin cast depending upon the system voltage and the surroundings. HT indoor transformers, for instance, are generally polyester or epoxy resin cast, and are economical with good dielectric properties. They are resistant to humid, chemically contaminated and hazardous areas. Outdoor HT transformers, how-ever. may be epoxy... 

Figure 15.3(a) Typical indoor epoxy resin cast instrument voltage transformers up to 11 kV (Courtesy Kappa Electricals)... 

All HT CTs are normally manul aclured with epoxy resin cast. 

Table 13.6 shows the characteristics and properties of supported and nonsupported high-molecular-weight epoxy resins cast from solvent solution. A crosslinked and uncrosslinked formulation using the same high-molecular-weight epoxy is shown for comparison. 

Table IX, Physical Properties of Polyamide-Epoxy Resin Castings...

The equilibrium water saturation measured of this epoxy resin casting sample was 0.90 %wt. Using the molar water content values reported by Van Krevelen ((1], Table 18.11 page 572), an equilibrium water concentration of 2.4 %wt. is calculated. 

Formulating with Dow Epoxy Resins Casting, Potting, and Encapsulation, Dow Form... 

CONTROL PROCEDURES FOR THE PRODUCTION OF EPOXY RESIN CASTINGS. 

Molds can range from hardwood for short runs to filled and unfilled high temperature polyester (TS) and epoxy resins, cast solid urethane, sprayed metal, cast aluminum, cast porous aluminum, and machined steels. The... 

TMA has already been considered in conjunction with glass transition measurements in applications such as degree of cure or heat-distortion temperatures of epoxy resin castings. The technique has proved useful for many other applications, some of which are described below. 

Table 5. Mechanical Properties of High Performance Epoxy Resins in Unreinforced Resin Castings...

The commercial possibiUties for epoxy resins were first recognized by DeTrey Emres in Switzerland and DeVoe and Raynolds in the United States (1,2). In 1936, DeTrey Emres produced a low melting bisphenol A-based epoxy resin that gave a thermoset composition with phthaUc anhydride. Apphcation of the hardened composition was foreseen in dental products, but initial attempts to market the resin were unsuccessful. The patents were hcensed to CIBA AG of Basel, Switzerland (now CIBA-GEIGY), and in 1946 the first epoxy adhesive was shown at the Swiss Industries Eair and samples of casting resin were offered to the electrical industry. 

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. 

Epoxy resins have outstanding mechanical and electrical properties, dimensional stability, resistance to heat and chemicals, and adhesion to other materials. They are used for casting, potting, encapsulation, protective coatings, and adhesives. Epoxy glues separate the resin from the curing. igciU to be mixed just prior to use. 

Epoxy resins for printed circuits, castings, rocket motor casings, coatings, and adhesives are almost all made from bisphenol A. Polycarbonates based on bisphenol A are used in glazing applications such as aircraft windows, school windows, and other areas where a combination of toughness and high clarity are required. 

P.Y.97 is also used to lend color to cast epoxy resins and to unsaturated polyester resins it considerably accelerates the hardening process in the latter (Sec. 1.8.3.7). 

Materials Description. Three CIBA-GEIGY epoxy/hardener systems were studied Araldite 6010/906, Araldite 6010/HY 917 and Araldite 6010/972 with stoichiometries 100/80, 100/80 and 100/27, respectively. Araldite 6010 was a DGEBA epoxy resin. The hardeners 906, HY 917 and 972 were, respectively, methyl nadic anhydride (MNA), methyltetrahydro phthalic anhydride (MTPHA) and methylene dianiline (MDA). These systems were investigated previously for the matrix controlled fracture in composites (6-8). The curing cycles used can be found in (6). The ideal chemical structures of the systems are shown in Table I. Neat resins were thoroughly degassed and cast into 1.27 cm thick plates for preparation of test specimens. 

Shell Epon 828 epoxy resin was cured with 13 PHR (parts per hundred of epoxy) of triethylene tetramine as a typical polyamine, 65 PHR of Shell Epon V-15 polyamide as a typical polyamide, or 130 PHR of dodecenyl succinic anhydride as a typical anhydride. Liquid formulations were cast in 5iluminum molds and oven-cured as follows ... 

---