Solid Epoxy

As pure materials, epoxies are brittle and have low fracture energies, ranging from 80 to 200 J/m (13). Materials whieh have been added to epoxy solids to improve toughness include hard particulate materials, (12) such as inorganic glass particles, as well as elastomers and thermoplastics such as polymethyl methacrylate. Silieone modifications of epoxies have also been made in order to improve toughness. 

Figure 3. Hydroxyl peak shift due to interaction with cycloaliphatic epoxy. Solid lines -probe acids in solvent, doted lines - after resin was introduced.

ABC acrylonitrile-butadiene-styrene ABR polyacrylate ABS acrylontrile-butadiene-styrene AC alternating current AC cellulose acetate ACES Accurate Clear Epoxy Solid ACS American Chemical Society ACTC Advanced Composite Technology Consortium ad adhesive... 

Meta-phenylenediamine, a crystalline solid with a melting point of about 60°C, gives cured resins with a heat distortion temperature of 150°C and very good chemical resistance. It has a pot life of six hours for a 200 g batch at room temperature whilst complete cures require cure times of four to six hours at 150°C. About 14 pts phr are used with the liquid epoxies. The main disadvantages are the need to heat the components in order to mix them, the irritating nature of the amine and persistent yellow staining that can occur on skin and clothing. The hardener finds use in the manufacture of chemical-resistant laminates. 

Solid epoxy resins based on the reaction product of epichlorohydrin and bisphenol A or bisphenol F mild to moderate irritants and mild sensitizers not readily absorbed through skin low volatility, exposure unlikely unless crushed or ground low toxicity... 

Fig. 5. Examples of ihe correlation between measured adhesive strength and (l+cos6). (a) Plot of data from Raraty and Tabor [171J for adhesion of ice to various solids, (b) Plot of data of Barbaris [172] for adhesion of a mixture of epoxy and polyamide resin to low density poly(ethylene) treated in various ways. Both figures from ref. [31], by permission.

Chemical Designations - Synonyms HEOD endo,exo-l,2,3,4,10,10-Hexachloro-6,7-epoxy-l,4,4a,5,6,7,8,8a-octahydro-l,4 5,8-dimethanonaphthalene Chemical Formula CjjHgCl O. Observable Characteristics - Physical State (as normally shipped) Solid Color Buff to light brown Odor Mild chemical. 

The materials of construction, from the cupboard to the fan, should be inorganic and resistant to attack by perchloric acid. For the cupboard itself suitable materials include stainless steel of types, 316 or 317, solid epoxy resin, and rigid PVC. Stainless steel has been popular for this application as it is easy to form, weld, and polish. It is, however, attacked by the acid, which causes discoloration of the metal surface and the formation of iron(III) perchlorate, which can be explosive. Ductwork, separate from other extract systems, is usually made from stainless steel or plastic materials. Fire regulations may preclude the use of plastic ductwork or require it to be sheathed in an outer casing of metal or GRP. The fan casing and impeller can both be made of plastic. 

Most comparisons of a failure criterion with failure data will be for the glass-epoxy data shown in Figure 2-36 as a function of off-axis angle 0 for both tension and compression loading [2-21]. The tension data are denoted by solid circles, and the compression data by solid squares. The tension data were obtained by use of dog-bone-shaped specimens, whereas the compression data were obtained by use of specimens with uniform rectangular cross sections. The shear strength for this glass-epoxy is 8 ksi (55 MPa) instead of the 6 ksi (41 MPa) in Table 2-3. 

Bisphenol A is a solid material in the form of white flakes, insoluble in water but soluble in alcohols. As a phenolic compound, it reacts with strong alkaline solutions. Bisphenol A is an important monomer for producing epoxy resins, polycarbonates, and polysulfones. It is produced by the condensation reaction of acetone and phenol in the presence of HCI. (See Chapter 10, p. 273)... 

Two-pack epoxies These were first patented in 1938 but were not in general production until 1947. They have been very widely used over the last decade. Produced from the by-products of the petroleum industry, the basic epoxy resins may be in the form of relatively low-viscosity liquid resins or they may be solid resins of increasing hardness. Both solid and liquid resins can then be reacted with a number of different curing agents. This means that almost any type of film and with any required properties can be made. 

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