Color chroma

Gr. chroma, color) Discovered in 1797 by Vauquelin, who prepared the metal the next year, chromium is a steel-gray, lustrous, hard metal that takes a high polish. 

LC can be used for both volatile and nonvolatile substances, but GC can handle only volatile substances. Chromatography was originally a method for separating and displaying mixtures of colored substances on a colorless column of solid material. The word chromatography is derived from chroma (color) and graph (writing). 

Chromium was first isolated and identified as a metal in 1789 by Vauquelin who was working with a rare mineral, Siberian red lead or crocoite [14654-05-08] PbCrO (3). The name chromium comes from the Greek word chroma color and resulted from the wide variety of brilliant colors... 

To illustrate this effect on colors, three single-pigment colors (blue, red, and yellow) were developed in three different resin systems. Blue and yellow were produced in acetal (POM), polyphenylene sulfide (PPS), and LCP. The red color was prepared in nylon 6,6, PPS, and LCP. The acetal and nylon resins are translucent while the PPS and LCP are opaque at the 3.2-mm sample thickness. In all three colors, the more translucent resins produced visually more brilliant, higher chroma colors than the more opaque resins with increased diffuse scattering. 

This discussion illustrates the effect light scattering of the polymer has on the resulting color. In real life, if LCP is required for a particular application, the examples in Table 23.3 show that deep, dark colors or bright, high-chroma ones cannot be achieved. A customer currently using these higher chroma colors in other resins such as polycarbonate needs to be educated that these same colors cannot be achieved in LCP... 

Antistatic additives are designed to be present on the surface of the molded part to achieve the full antistatic benefit. The types of additives used to enhance antistatic properties include quaternary ammonium salts, alkyl sulfonates or phosphate plus alkali metals, ethoxylated amines, or gylcerol esters. Antistatics are typically used at higher levels than other additives such as antioxidants. Therefore, antistatics are likely to increase light scattering, making it more difficult to achieve the higher chroma colors. 

Cr chromium, 24, 1797 from the Greek chroma (color) since it is used in pigments (e.g., chrome yellow). 

Of these barriers, the one that is most overlooked is the first. Many of the new thermoplastic materials coming into the market place are blends and alloys that are specifically engineered to provide a combination of the properties of the individual polymers. Often these materials combine crystalline and amorphous polymers with an impact modifier. The products of these marriages often contain a maze of phase boimdaries that result in light scattering (miUdness) equivalent to as much as 0.5% titanium dioxide. Obtaining high chroma colors (e.g., some electrical code colors or even a jet black) in the presence ofthis inherent miUdness becomes an expensive proposition. Often so much color has to be added to the material formulation that critical material properties are affected - a double whammy, cost and performance. 

Features Patented creates multicolor effects, brilliant color, glittering et-tects outperforms traditional pearlescent pigments in chroma, color purity, brightness, transparency, and retlectivity Regulatory Approved tor food contact FireShield H [Laurel Ind. Hatwick Std. Distrib.]... 

Metachromasia, from meta, a change in the kind of, and chroma, color, refers to the qualitative change which occurs in the color of certain dyes when they interact with other substances. The term was originally applied by Paul Ehrlich to the phenomenon of color change when a dye is adsorbed onto a substrate. Thus, cartilege and other mucopolysaccharide-containing tissues are stained red by toluidine blue. Similarly, Hartley observed that when bromophenol blue solution is added to cetrimide solution the color changes from purplish blue to clear blue. 

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