Optical properties product

Methyl methacrylate is only one of a family of monomers, including the various esters of acrylic, methacrylic, and ethacrylic acids, which are polymerized to produce the thermoplastic resins known as the acrylates. A wide variety of reactions and starting materials may be utilized for their production however, the principal commercial product is polymethyl methacrylate, sold by Du Pont and Rohm Haas under the trade names of Lucite and Plexiglas, respectively. These materials were introduced to the United States market in 1936 (44) and have received widespread acceptance due principally to their outstanding optical properties. Production in 1949 was reported as about 22,000,000 to 25,000,000 pounds and peak wartime capacity was above30,000,000 pounds. While this can account for only about 2% of the current production of propylene for chemical purposes, the acrylate resins are of considerable commercial importance as they are sold at a relatively high price and are the only materials available that will meet the requirements for certain military and civilian products. 

Optics. Good optical properties and low thermal resistance make poly(methyl methacrylate) polymers well suited for use as plastic optical fibers. The manufacturing methods and optical properties of the fibers have been reviewed (124) (see Fiber optics). Methods for the preparation of Fresnel lenses and a Fresnel lens film have been reported (125,126). Compositions and methods for the industrial production of cast plastic eyeglass lenses are available (127). 

One of the requirements of this process is that the melt maintain good contact with the chill roU, ie, air must not pass between the film and the roU. Otherwise, air insulates the plastic and causes it to cool at a rate different from the rest of the plastic and this spoils the appearance of an otherwise satisfactory product. The melt should not emit volatiles, which condense on the chill roU, reduce heat transfer, and mar the film s appearance. The cast film process allows the use of a higher melt temperature than is characteristic of the blown film process. The higher temperature imparts better optical properties. 

Tantalum and niobium are added, in the form of carbides, to cemented carbide compositions used in the production of cutting tools. Pure oxides are widely used in the optical industiy as additives and deposits, and in organic synthesis processes as catalysts and promoters [12, 13]. Binary and more complex oxide compounds based on tantalum and niobium form a huge family of ferroelectric materials that have high Curie temperatures, high dielectric permittivity, and piezoelectric, pyroelectric and non-linear optical properties [14-17]. Compounds of this class are used in the production of energy transformers, quantum electronics, piezoelectrics, acoustics, and so on. Two of... 

The contaminated powdered material usually causes problems during crystal growth and degraded the electric and optic properties of the final products. 

The main techniques employed in quantitative analysis are based upon (a) the quantitative performance of suitable chemical reactions and either measuring the amount of reagent needed to complete the reaction, or ascertaining the amount of reaction product obtained (b) appropriate electrical measurements (e.g. potentiometry) (c) the measurement of certain optical properties (e.g. absorption spectra). In some cases, a combination of optical or electrical measurements and quantitative chemical reaction (e.g. amperometric titration) may be used. 

The shape of a photometric titration curve will be dependent upon the optical properties of the reactant, titrant, and products of the reaction at the wavelength used. Some typical titration plots are given in Fig. 17.23. 

Within the limitations on the physical properties which generally restrict plastics to low precision optics, plastics materials have found wide applications in optical products that range from lights to binders for electroluminescent phosphors to fiber optics and lasers. They represent an easily worked material with a wide range of desirable optical properties in simple to complex shapes. In this review the discussion has been limited to the differences between plastics and optical glass materials and to some of the unique design possibilities that are especially important for plastics. Using the optical arts and the... 

The pace of development has increased with the commercialization of more engineering plastics and high performance plastics that were developed for load-bearing applications, functional products, and products with tailored property distributions. Polycarbonate compact discs, for example, are molded into a very simple shape, but upon characterization reveal a distribution of highly complex optical properties requiring extremely tight dimension and tolerance controls (3,223). 

The III-V and II-VI compounds refer to combination of elements that have two, three, five, or six valence electrons. They have semiconductor properties and are all produced by CVD either experimentally or in production. The CVD of these materials is reviewed in Ch. 12. Many of their applications are found in optoelectronics where they are used instead of silicon, since they have excellent optical properties (see Ch. 15). Generally silicon is not a satisfactory optical material, since it emits and absorbs radiation mostly in the range of heat instead of light. 

The creation of microstmcture with well-defined electrical or optical properties is critical to the production of integrated circuits and recording materials. The processes used to define... 

By the use of microstructured mixers, pigment and other particulate syntheses can be improved. In this way, finer particles with more uniform size distribution were yielded for the commercial azo pigment Yellow 12 (see Fig. 2) [11]. The particles formed in the microstructured mixer have better optical properties such as the glossiness or transparency at similar tinctorial power. Since the micro-mixer made pigments have more intense colour, lower contents of the costly raw material in the commercial dye products can now be employed which increases the profitability of the pigment manufacture. 

Electrochemical as well as nonelectrochemical techniques are used when studying these aspects. Electrochemical techniques are commonly used, too, in chemical analysis, in determining the properties of various substances and for other purposes. The nonelectrochemical techniques include chemical (determining the identity and quantity of reaction products), radiotracer, optical, spechal, and many other physical methods. Sometimes these methods are combined with electrochemical methods for instance, when studying the optical properties of an electrode surface while this is polarized. Nonelectrochemical techniques are described in more detail in Chapter 27. 

Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (SijN ), and boron nitride (BN) offer a wide variety of unique physical properties such as high hardness and high structural stability under environmental extremes, as well as varied electronic and optical properties. These advantageous properties provide the driving force for intense research efforts directed toward developing new practical applications for these materials. These efforts occur despite the considerable expense often associated with their initial preparation and subsequent transformation into finished products. 

Processes such as film extrusion, fiber spinning, injection molding, and drawing tend to impart orientation to products made from semicrystalline polymers. Mechanical, dielectric, and optical properties, to mention only three, are often strongly influenced by orientation. X-ray diffraction offers a direct approach to studying crystallite orientation because the Intensity that is diffracted into a detector placed at an appropriate position is directly proportional to the number of crystal lattice planes that are in the correct orientation for diffraction. The principles of such measurements are well described in textbooks 0,2). 

Nitrogen heterocycles are especially interesting, since they constitute an important class of natural and nonnatural products, many of which exhibit useful optical properties these have been recently synthesized and evaluated as probes in bioassays purposes 141 —441. Despite the diversity of these compounds, benzoxadiazole, acridone, and acridine fluorophores were chosen as a focus in biolabeling applications. 

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