RADIA TORFLUID
The active ingredient in radiator fluid is ethylene glycol, a two-carbon diol, which is used because of its low freezing point and high boiling point. A fluorescein dye is often added to readily identify antifreeze and make it less palatable to animals. Radiators are used with internal combustion engines to cool the engine block and pistons and maintain their specified operating temperatures. An engine’s water pump circulates the coolant through the engine block and back to the radiator, where the heat is dissipated by passage through air-cooled coils. Initially, water was circulated to cool automobile engines. In areas with cold winters, the water would freeze and destroy the delicate thin-walled coils in the radi- ator, causing leaks that lead to overheating. Ethylene glycol has a freez- ing point lower than the frigid temperatures that caused water-cooled engine problems. Ethylene glycol has the added advantage that the boil- ing point is higher than that of water, allowing the fluid to operate over a wider range of temperatures than alternative substances. The tempera- ture of the engine is controlled by the radiator fluid removing heat from the engine through the radiator, and the maximum coolant temperature is controlled with a high-temperature thermostat to control the flow rate of the liquid cooling the engine.
Ethylene glycol has a characteristically sweet smell that makes it irre- sistible to animals. The bright green or red fluorescein dye is added to warn humans and animals of the inherent danger associated with the in- gestion of antifreeze. If antifreeze is swallowed, it causes central nervous system depression followed by respiratory and cardiac distress. If untreated, ingestion leads to cardiac failure, renal failure, and brain damage.
SUPER GLUE
Superglue is ethyl-2-cyanoacrylate, which when applied to surfaces bonds and polymerizes, forming a strong bond between materials. It was discovered accidentally by an employee of Kodak Research Labs who was trying to develop an optically clear plastic for gun sights during World War II. He found that everything that the acrylate monomers touched would stick together so well that it was difficult to get the pieces apart once the acrylate cured.
Superglue is an acrylic resin that bonds to most materials instantly, and the polymerization is triggered by the hydroxide ions in water. It undergoes a process called anionic polymerization, in which the cyanoacry- late monomers link together when they come into contact with water. The chains form a durable plastic mesh that continues to cross-link until the polymer strands can no longer move. These polymers bind the surfaces being glued together by millions of polymeric strands, giving the bond exceptional strength. It is primarily used in repair work on consumer items but has recently been used successfully by forensic examiners to develop latent fingerprints and to close surgical wounds without stitches.
The polymerization process of cyanoacrylates is so fast that it can react with the water present on skin, causing it to bond skin instantly. As such, it should be handled with extreme care, because a small amount rubbed in the eye can instantly bond eyelids shut. It causes irritation of the nose, throat, and lungs from the noxious vapors of the acrylate monomer. There are different commercially available chemical variants that have slightly different setting properties and viscosities depending upon the application.
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