Chemical vapor curing

CVC chemical vapor curing DDR draw down ratio... 

Chemical vapor polymerization of polyimides follows a different route from that of parylenes described above, in that, it is usually a two step process. First the monomers are adsorbed on the surface of the substrate resulting in the formation of a short-chained oligomer intermediate, and then the films are cured at a higher temperature ( 300°C) to form the desired... 

Cold Vulcanization. — The material in thin strips, or sheets, is passed through, or dipped into a solution of sulfur chloride (S2CI2) in carbon disulfide, or carbon tetrachloride. Some of the sulfur chloride remains united, physically or chemically, with the caoutchouc, and the excess is neutralized with ammonia. By this process the goods acquire a soft velvet feel, but unfortunately are liable to perish rather easily. A variation of the method, technically known as the vapor cure, consists of treating the goods with the vapors of sulfur chloride. Subsequent neutralization with ammonia is, of course, necessary. 

Aliphatic amines Convenience Room temperature cure, fast elevated-temperature cure Low viscosity Low formulation cost Moderate chemical resistance Critical mix ratios Strong skin irritant High vapor pressure Short working life, exothermic Poor bond strength above 80°C Rigid, poor peel and impact properties Adhesives and sealants Casting and encapsulation Coatings... 

Solvents and diluents are used to lower the viscosity of epoxy resins systems either to permit easy compounding with other ingredients or to aid in application of the adhesive onto a substrate. Both solvents and diluents are low-molecular-weight liquid compounds that are chemically and physically compatible with epoxy resins and their curing agents. They differ primarily by their vapor pressure. 

Fillers often have a significant effect on the moisture resistance, the moisture-vapor transmission rate, and the solvent and chemical resistance of the cured adhesive bond. The effect, however, can be in either direction. Some fillers such as calcium carbonate tend to lower acid resistance, whereas others, such as silica or aluminum, may tend to lower alkali resistance. 

Eyes, Nose, and Throat. All the epoxy resins are low in acute oral toxicity. However, most epoxy chemicals and their vapors can irritate the eyes, nose, and throat. Some people develop headaches as a result of this irritation. Eye contact with epoxy resins could result in slight, transient irritation. However, curing agents, solvents, and diluents can cause severe irritation. In event of eye contact, the eyes should immediately be flushed with plenty of water and then medical attention sought. 

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