Sealing epoxy cement

Epoxy cement sealing. Epoxy cement sealing is done by filling a groove in the cover with epoxy cement. The battery is inserted and positioned so the... 

The majority of secondary silver cells are assembled in plastic cases. The plastic most commonly used is an acrylonitrile-styrene copolymer (SAN). This material is relatively transparent and can be sealed easily by solvent cement or epoxy. However, its relatively low softening temperature (80°C) precludes it from use in some applications. A wide variety of other plastics have been used for cell cases. Table 33.2 lists some of these materials and gives their characteristics. Metal cases have been used for some sealed cell and button ceU applications however, these present problems in sealing and in electrically isolating the electrodes from the cases and are not used widely. 

Certain polymer adhesives with a low percentage of volatile constituents are vacuum compatible and may be used in a vacuum environment if temperatures are kept within allowable limits. For example, Torr-seal epoxy cement is a low vapor pressure epoxy material that it is possible to use to 100°C. Where electrical conductivity is desired, copper or silver flakes can be added to the adhesive. 

Seals Seals are normally transparent, quick-drying, highly penetrating materials that are used to stop cement dusting and contamination by oils, etc. The moisture-cured urethanes are particularly suitable, since they penetrate to produce a hard-wearing surface. However, if safety factors preclude their use there are also epoxy and even oleo-resinous products available. 

Macroelectrodes with solid membranes contain homogeneous [142] or heterogeneous [25] membranes. The construction of an ISE of this type with an internal reference electrode is shown in fig. 4.1. For good functioning of an ISE it is necessary that the membrane be completely sealed in the electrode body, with no cracks leading to short-circuiting between the external and internal solutions. Cements based on Teflon, PVC or epoxy resin are used (170). 

Carbon electrodes. The vitreous carbon electrode usually is fabricated by sealing a plug or disk, but from a thick sheet of glassy carbon, into a glass tube with epoxy cement. The surface of the electrode is then polished until it is bright and smooth. No further treatment is necessary. 

Figure 5.38 illustrates a rotated disc electrode that is surrounded by a concentric shell of light wires sealed in epoxy cement. Products produced electro-chemically at the disc electrode are swept past the light wires, and their spec-tram is recorded by slowly scanning with the monochromator.139... 

The glass slides and spacers should be sandwiched together and the two long lateral sides sealed using an epoxy cement such as Torr Seal or Kwik. To ensure a uniform spacing, the slides should be evenly clamped between two flat 0.5"-wide bars while the epoxy dries. The edges of the slides should first be scraped with a razor blade to remove any... 

The floor of the storage site should be made of sealed cement, glazed ceramic tile, no-wax sheet flooring, or another easily cleaned material. Carpeting, wood, soil, and other absorbent floors are difficnlt or impossible to decontaminate in case of a leak or spill. For ease of cleannp, shelving and pallets should be made of nonabsorbent materials snch as plastic or metal. If wood or fiberboard materials are nsed, they should be coated or covered with plastic or polyurethane or epoxy paint. 

Polyesters and expoxies have been used to seal cracks in rock formations and to anchor rock reinforcement members in drilled holes. The mechanical properties of these materials are much better than those of Portland cement. However, the chemicals are (relative to other grouts) very expensive and very viscous. Rendering them less viscous by using diluents so that they will penetrate sands makes them even more expensive. Because of their limited application as grouts, polyesters and epoxies are not detailed further. 

In low temperature studies, it is preferable to mount the crystal in a flow cell [215]. This permits the gradual change of cryoprotectant concentration as the temperature is lowered and substrate is introduced into the crystal. A quartz capillary is attached to a brass support by epoxy cement and a tight-fitting polyethylene tube sealed to the bottom of the capillary. The capillary is filled with protein mother liquor solution. The crystal is introduced to the top and allowed to settle either on to a bed of pipe cleaner fibres placed on top of the polyethylene tube as support or on to a support made by previously introducing a constriction into the quartz capillary. The crystal may be secured further by additional fibres. The inlet polyethylene tube is sealed to the top of the capillary. The inlet and outlet tubes are then connected to the reservoir and sink, respectively (Fig. 13). 

Epoxy resin cements have been used to seal leaking metal gas plpesil and for many civil engineering applications, such as steel wire-reinforced epoxy resin cements— and the reconstruction of the Abu-Simbul Temple in Egypt.— Epoxy resin cements whose physical properties are similar to those of concrete— are discussed more completely in Chapters 3, 4 and 5. 

These resin cement systems require only moderate capital investment, yet can yield dramatic results. For example, the many thousands of cracks in the Los Angeles City Hall produced by the 1971 earthquake were repaired by the use of 20 thousand gallons of an aluminum and ceramic filled epoxy resin mortar.— Likewise, wood whose cracks have been sealed by polyurethane mortars is suitable for continuous lathe cutting for veneer manufacture. 

The more viscous, mastic-type cements include some of the epoxies, urethanes and sflicones. Epoxies adhere well to both thermosets and thermoplastics. But epoxies are not recommended for most polyolefin bonding. Urethane adhesives have made inroads into flexible packaging, the shoe industry, and vinyl bonding. Polyester-based polyurethanes are often preferred over polyether systems because of their higher cohesive and adhesive properties. Sflicones are especially recommended where both bonding and sealing are desired. 

As is described in Chapter 10, several different materials have been considered as sealants. These include zinc oxide-eugenol cements, epoxy resins and glass-ionomer cements [73,74]. In addition, calcium hydroxide paste has been used, though this material appears to be susceptible to leakage and may not be entirely satisfactory in forming a durable seal. However, its bioactivity is able to promote the physiological closure of the apex with dentine and cementum via stimulation of the odontoblast and cementoblast cells present [75]. 

Epoxy glue seal An epoxy glue seal employs either solvent cement or a thermal seal. These types of seals are often used for stationary batteries and traction cells so that coolant can be circulated through the terminals. 

---