Dissolved in plastics

Several solid materials, such as organics dissolved In plastics (,22,23), phosphors sintered with polytetrafluoroethylene (30), phosphors (31), and lumogen-T (23), have been suggested as calibration standards. But most of the publications suggesting these materials (except Ref. 31) have not Included digital data for the corrected spectra. Additional Information, precautions, and pitfalls to be aware of In the use of various standards have been summarized In Reference 11 and the references cited therein. 

Sensitivity, Linearity, and Stability of Instruments. Quinine sulfate has been suggested as a standard for determining the limit of detection and linearity of Instruments (44). Some organic materials dissolved In plastics have been suggested as standards because of their stability (22), and many Inorganic Ions dissolved In glasses are quite stable. 

The selective determination of Cu(II) was accomplished by making use of pyrocatechol violet indicator, dissolved in plasticized PVC membrane as a... 

Figure 7. Schematic representation of the microenvironment of the cationic PSD diOC16(3) in a potassium sensor before (A) and after (B) extraction of potassium from the aqueous into the lipophilic membrane phase. The sensor membrane is composed of valinomycin, diOC16(3) and a lipophilic borate salt dissolved in plasticized PVC.

Nitramine (RDX or HMX) oxidizer Homogeneous colloidal propellant consisting of nitrocellulose dissolved in plasticizer comprised of nitroglycerine and inert materials Composite or double-base propellant in which polymer is dissolved in plasticizier... 

The deviation from a single exponential curve for the phosphorescence decay of some chromophores dissolved in plastics was first noted by Oster et al.(19) Nonexponential decay curves were obtained for naphthalene and triphenylene phosphorescence in polyCmethyl methacrylate) (PMMA) at room temperature (20), while exponential decays at room temperature were observed in PMMA for anthracene triplet (21), pyrene (22), and coronene phosphorescence (20). Graves et al. (23) analyzed the temperature dependence of phosphorescence parameters for a number of aromatic hydrocarbons in PMMA from 77 to 400K and suggested the existence of intermolecular thermally assisted energy transfer from the chromophore to the host plastic in the higher temperature region. 

Fig. 15. Hybrid luminescent solar concentrator. In this example, the upper plate is a uranyl glass plate functioning as the upper plate on Fig. 2, followed by a narrow air gap, and then a colourless glass plate, on which an organic dye (dissolved in plastic) is on the underside. Contrary to the case of Fig. 2, the lowest part of the device is a second air gap, followed by a mirror. Luminescent radiation emitted downward by the dye-stuff is then reflected by the mirror, and recovered for total reflections in the lower plate...

The spontaneous dissolution should be accompanied by a decrease in the free energy (AG < 0), and this is only possible at some definite values of AH and AS. As highly elastic polymers dissolve AH > 0, AS > 0, then AG < 0. Therefore highly elastic polymers can completely dissolve in plasticizers. Their dissolution is promoted by chain flexibility becanse the flexible chains diffuse into solntion in a piecemeal maimer. This process is accompanied by increase in entropy. The dissolution of flexible polymers has a diffusive character. 

Non-exponential phosphorescence decay of some chromophores dissolved in plastics were first noted by Oster et al. Such decay curves were found for naphthalene and triphenylene phosphorescence in poly(methyl methacrylate) (PMMA) at room tanperature However, the decay in PMMA at room temperature were exponential for the anthracene triplet pyrene and coronene phosphorescmce... 

The first ion-selective polymer electrodes were constructed by Simon and Stefanac [12], who obtained electrodes for determination of K and NH/by using macrocyclic antibiotics dissolved in plasticized PVC. During the same period, Ross [13] described an electrode selective towards Ca ions with a lipophilic, phospho-organic acid placed in a plasticized PVC matrix. 

To prepare the standard pH buffer solutions recommended by the National Bureau of Standards (U.S.), the indicated weights of the pure materials in Table 8.15 should be dissolved in water of specific conductivity not greater than 5 micromhos. The tartrate, phthalate, and phosphates can be dried for 2 h at 100°C before use. Potassium tetroxalate and calcium hydroxide need not be dried. Fresh-looking crystals of borax should be used. Before use, excess solid potassium hydrogen tartrate and calcium hydroxide must be removed. Buffer solutions pH 6 or above should be stored in plastic containers and should be protected from carbon doxide with soda-lime traps. The solutions should be replaced within 2 to 3 weeks, or sooner if formation of mold is noticed. A crystal of thymol may be added as a preservative. 

In the case of poly(vinyl chloride) plastics, the FWA is mixed dry with the PVC powder before processing or dissolved in the plasticising agent (see Vinyl polymers). Polystyrene, acrylonitrile—butadiene—styrene (ABS), and polyolefin granulates are powdered with FWA prior to extmsion (2,78) (see... 

Corrosion. Ammonium bifluoride dissolves in aqueous solutions to yield the acidic bifluoride ion the pH of a 5% solution is 3.5. In most cases, NH4HF2 solutions react readily with surface oxide coatings on metals thus NH4HF2 is used in pickling solutions (see Metal surface treatments). Many plastics, such as polyethylene, polypropylene, unplasticized PVC, and carbon brick, are resistant to attack by ammonium bifluoride. 

Docusate Sodium. Aerosol OT, Colace, and Doxinate are trade names of docusate sodium [577-11-7] (dioctyl sodium sulfo succinate, sodium salt of l,4-bis(2-etliylhexyl)estet butanedioic). This white, wax-like, plastic sohd, with a characteristic odor suggestive of octyl alcohol, is usually available in the form of pellets. One gram of the sodium salt slowly dissolves in about 70 mL water. Docusate sodium is freely soluble in alcohol and glycerol, very... 

Plastics. Vehicles in offset inks for plastics (polyethylene, polystyrene, vinyl) are based on hard drying oleoresinous varnishes which sometimes are diluted with hydrocarbon solvents. Letterset inks for polystyrene employ vehicles of somewhat more polar nature. Polyester or other synthetic resins (acryhc) dissolved in glycol ethers and/or esters are used in some of the older inks. Uv inks are widely used for decoration of these preformed plastic containers. 

Individual particle surfaces can be lubricated by an adsorbed film that produces a smoother surface and/or decreases interparticle attraction. A plasticized binder may serve this purpose. Forming surfaces can be lubricated by coating with a film of low viscosity Hquid such as water or oil. Die surfaces can also be coated with a solution of stearic acid dissolved in a volatile Hquid that rapidly evaporates to leave a lubricating film. 

Liquids. Liquids (33) are common forming additives in plastic, paste, and slurry processing. In plastic forming operations, the Hquid aids forming and serves as the binder/plasticizer for the system. In pastes and slurries, other additives are also dissolved or dispersed in the Hquid/solvent. Water is a good, inexpensive solvent that can be recycled. Organic Hquids such as alcohols are used to process water-sensitive materials and to dissolve water-insoluble forming additives, however, at considerably more expense. 

To reduce the amount of dust produced, water can be added to the abrasive from a circular water sprayer around the no22le. Chemical corrosion inhibitors must be dissolved in the water to prevent flash msting of the steel. Newer methods to reduce dust include the use of ice, soHd carbon dioxide (dry ice), or plastic beads as abrasives. Blasting with dry ice is inexpensive and effective, but the accumulation of carbon dioxide must be avoided in enclosures. Plastic beads are inexpensive, but the cutting efficiency is low and paint removal is slow the beads can be cleaned of paint particles and reused. 

Cobalt(II) phosphate octahydrate [10294-50-5], Co2(P0272 8H20, is a red to purple amorphous powder. The product is obtained by reaction of an alkaline phosphate and solutions of cobalt salts. The material is insoluble in water or alkaU, but dissolves in mineral acids. The phosphate is used in glazes, enamels, pigments (qv) and plastic resins, and in certain steel (qv) phosphating operations (see Enamels,PORCELAIN ORVITREOUS). 

Electroforrning is the production or reproduction of articles by electro deposition upon a mandrel or mold that is subsequendy separated from the deposit. The separated electro deposit becomes the manufactured article. Of all the metals, copper and nickel are most widely used in electroforming. Mandrels are of two types permanent or expendable. Permanent mandrels are treated in a variety of ways to passivate the surface so that the deposit has very Httie or no adhesion to the mandrel, and separation is easily accompHshed without damaging the mandrel. Expendable mandrels are used where the shape of the electroform would prohibit removal of the mandrel without damage. Low melting alloys, metals that can be chemically dissolved without attack on the electroform, plastics that can be dissolved in solvents, ate typical examples. 

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