Optically transparent plastics

The use of optically transparent plastics in windshield canopies and other glazing areas is another example of their functional use. Low K-... 

Other authors, such as Yano and co-workers (2005) have indicated the extraordinary potential of nanocellulose as a reinforcement material in optically transparent plastics, for instance, or as a substrate for bendable displays. In their opinion, the composite remained optically transparent even at high fiber contents. 

From ships to submarines to mining the sea floor, certain plastics can survive sea environments, which are considered more hostile than those on earth or in space. For water-surface vehicles many different plastic products have been designed and used successfully in both fresh and the more hostile seawater. Figure 2-55 is an example where extensive use is made using unreinforced and reinforced plastics meeting structural and nonstructural product requirements. Included are compartments, electronic scanners, radomes, optically transparent devices, food storage and dispensing containers, medical products, buoyant devices, temperature insulators, and many more. 

Photoelastic measurement is a very useful method for identifying stress in transparent plastics. Quantitative stress measurement is possible with a polarimeter equipped with a calibrated compensator. It makes stresses visible (Fig. 5-2). The optical property of the index of refraction will change with the level of stress (or strain). When the photoelastic... 

This photoelastic stress analysis is a technique for the nondestructive determination of stress and strain components at any point in a stressed product by viewing a transparent plastic product. If not transparent, a plastic coating is used such as certain epoxy, polycarbonate, or acrylic plastics. This test method measures residual strains using an automated electro-optical system. 

These qualities are considered in most applications for transparent plastics, forming a basis for directly comparing the transparency of various grades and types of plastic. The data are of value when a material is considered for optical purposes. Many transparent plastics do not have water clarity, and, for this reason, the data should indicate whether... 

Opacity or transparency is important when the amount of light to be transmitted is a consideration. These properties are usually measured as haze and luminous transmittance. As reviewed haze is defined as the percentage of transmitted light through a test specimen that is scattered more than 2.5° from the incident beam. Luminous transmittance is the ratio of transmitted light to incident light. Table 5-7 provides the optical and various other properties of different transparent plastics. 

In this test for transparent plastics, the loss of optical effects is measured when a specimen is exposed to the action of a special abrading wheel. In one type of test the amount of material lost by a specimen is determined when the specimen is exposed to falling abrasive particles or to the action of an abrasive belt. In another test, the loss of gloss due to the dropping of loose abrasive on the specimen is measured. The results produced by the different tests may be of value for research and development work when it is desired to improve a material with respect to one of the test methods. The variables that enter into tests of this type are... 

In IMS, supportive materials, whose surfaces are coated with conductive materials, are used in principal. In the simplest way, the tissue slices can be placed on a metal MALDI plate directly.9 In this case, however, the target plate must be cleaned carefully after the measurement is over. Currently, the method commonly used is that samples are prepared on a disposable plastic sheet or a glass slide coated with series of conductive materials. In particular, a plastic sheet (ITO sheet) or glass slide (ITO glass slide available from Bruker Daltonics K.K., Billerica, MA, or Sigma, St. Louis, MO) coated with ITO (indium-tin oxide) is useful because it has superior optical transparency... 

The index of refraction of transparent plastics may be determined by placing a drop of a specified liquid on the surface of the polymer before measuring the index with a refractometer. An optical microscope is used to measure the index of refraction in an alternative method (ASTM-D542). 

In a typical spectroelectrochemical measurement, an optically transparent electrode (OTE) is used and the UV/vis absorption spectrum (or absorbance) of the substance participating in the reaction is measured. Various types of OTE exist, for example (i) a plate (glass, quartz or plastic) coated either with an optically transparent vapor-deposited metal (Pt or Au) film or with an optically transparent conductive tin oxide film (Fig. 5.26), and (ii) a fine micromesh (40-800 wires/cm) of electrically conductive material (Pt or Au). The electrochemical cell may be either a thin-layer cell with a solution-layer thickness of less than 0.2 mm (Fig. 9.2(a)) or a cell with a solution layer of conventional thickness ( 1 cm, Fig. 9.2(b)). The advantage of the thin-layer cell is that the electrolysis is complete within a short time ( 30 s). On the other hand, the cell with conventional solution thickness has the advantage that mass transport in the solution near the electrode surface can be treated mathematically by the theory of semi-infinite linear diffusion. 

Dicthylcncglycol-lm-(allylcarbonatc). marketed as C.R-39 . is finding increasing use where optical transparency is required. It is the primary material used in the manufacture of plastic lenses for eyewear because of its light weight, dimensional stability, abrasion resistance, and dye-ability. Other applications for this product include instrument panel covers, camera filters, and myriad glazing uses. In these applications, the solvent and chemical resistance of die material are important. 

Reagents and indicators are immobilized, occluded or dissolved in supports which are formed by cross-linked polymers, plasticized polymers or organic and inorganic activated surfaces. The waveguide itself, the cladding of an optical fiber or any other optical element can be the support. However, it must obey two basic functions act as a liquid-solid or gas-solid interface and, if radiation crosses through it to allow the signal transmission, be an optically transparent material. 

The main disadvantage is that at least one of the substrates must be transparent to the radiation initiating cure. This requirement prevents also the filling or pigmenting of such materials. Nevertheless, many applications are being developed—bonding glass, transparent plastics, jewellery, and optical fibres. 

Optically transparent electrode — (OTE), the electrode that is transparent to UV-visible light. Such an electrode is very useful to couple electrochemical and spectroscopic characterization of systems (- spectroelectro-chemistry). Usually the electrodes feature thin films of metals (Au, Pt) or semiconductors (In203, SnCb) deposited on transparent substrate (glass, quartz, plastic). Alternatively, they are in a form of fine wire mesh minigrids. OTE are usually used to obtain dependencies of spectra (or absorbance at given wavelengths) on applied potentials. When the -> diffusion layer is limited to a thin layer (i.e., by placing another, properly spaced, transparent substrate parallel to the OTE), bulk electrolysis can be completed in a few seconds and, for -> reversible or - quasireversible systems, equilibrium is reached for the whole solution with the electrode potential. Such OTEs are called optically transparent thin-layer electrodes or OTTLE s. 

Finally, optically transparent electrodes comprised of Sn02 or ln203 thin films on glass, quartz, or plastic are widely used to study electrochemical reactions under illumination in solution. Spectral studies of reactants, intermediates, or products can be also performed to gain some molecular insight into electrode kinetics. 

Additional opportunities in the styrene plastics industry exist for the development of products having such unique properties as high heat resistance and optical transparency. Arco produces the Dylark family of heat-resistant styrene plastics, which are copolymers of styrene-maleic anhydride. These products have a good balance of mechanical properties and have a heat distortion (under ASTM D68) of 234 F (33) which is markedly higher than homo polystyrene. 

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