Water-clear transparency

Water-clear transparency is probably the single unique and most important attribute of polycarbonate. It is of such importance because there are very few transparent polymers—especially with high optical properties. The vast majority of polymers are opaque, with a few families providing degrees of translucency. And while it is certainly true that polycarbonate is of interest in applications other than those requiring clarity, it is also true that approximately one-half of all the polycarbonate sold is formulated... 

In the eady 1920s, experimentation with urea—formaldehyde resins [9011-05-6] in Germany (4) and Austria (5,6) led to the discovery that these resins might be cast into beautiful clear transparent sheets, and it was proposed that this new synthetic material might serve as an organic glass (5,6). In fact, an experimental product called PoUopas was introduced, but lack of sufficient water resistance prevented commercialization. Melamine—formaldehyde resin [9003-08-1] does have better water resistance but the market for synthetic glass was taken over by new thermoplastic materials such as polystyrene and poly(methyl methacrylate) (see Methacrylic polya rs Styrene plastics). 

Similar investigations have been carried out on water in oil microemulsions. A microemulsion is a clear, transparent, and stable system consisting of essentially monodisperse oil in water (OAV) or water in oU (W/O) droplets with diameters generally in the range of 10-200 nm. Microemulsions are transparent because of their small particle size, they are spherical aggregates of oil or water dispersed in the other liquid, and they are stabilized by an interfacial film of one or more surfactants. 

Hahn s Explosive. A cheap explosive mixture prepared as follows Burnt lime was dissolved in raw, odorless nitric-acid so as to produce a clear transparent fluid resembling petroleum jelly. This fluid was diluted with 1 to 5 parts of water according to the desired explosive power, and then mixed with a powdered cellulosic material such as peat, sawdust, etc, until a consistant mass was obtained. After giving this mass any suitable form, it was dried and used as a... 

The clear transparent rhombohedral crystals of a-Na2C03.7H20 are unstable and readily pass into the rhombic bipyramidal crystals of /3-Na2C03.7H20. The crystals of the a-salt Boon become milk-white owing to the formation of the decahydrated salt by the re-crystallization of the heptahydrated carbonate moist with the adherent water. The solubility curve is indicated in Eig. 68. H. Lowel prepared the unstable rhombohedral or a-salt in the following maimer ... 

To a solution of 6.7 g of sodium amide in 100 ml of anhydrous diethyl ether was added dropwise 26 g of 4-isobutylbenzene cyanide while the mixture was stirred and heated under gentle reflux. After all of the 4-isobutylbenzene cyanide had been added, the mixture was heated under gentle reflux for 15 min, after which 23.4 g of ethyl iodide was slowly added dropwise thereto from the dropping funnel. After completion of the addition of the ethyl iodide, the mixture was heated under gentle reflux for an initial period of 15 min, after which it was diluted with an equal volume of water and shaken. The two layers that formed were separated and the aqueous layer was then extracted with two 50 ml portions of diethyl ether. The ether extracts were combined and then washed with two 80 ml portions of water and dried over anhydrous magnesium sulfate. The dried ether extract was then distilled at a subatmospheric pressure. In this manner, 25 g of a clear transparent uncolored liquid having a boiling point of 118-122°C at a pressure of 1mm of mercury, which consisted of 2-(4-isobutylphenyl)butyronitrile, was collected. This yield was equivalent to 83% of the theoretical. 

Fig. 2 Optical images of aminoday-metal nanoparticle composites forming clear transparent solutions in water (a) aminoclay solution, and aminoclay with (b) Au, (c) Ag, (d) Pt and (e) Pd nitnopartides.

Fig. 2 shows how the aminoday -metal nanoparticle composites form clear transparent solutions in water. The solutions are pink and yellow for Au and Ag respectively and dark brown in the cases of both Pt and Pd. The reddish-brown colour observed for Au-clay nanoparticle composites immediately after the addition of NaBH4 changed to pink with time. The solutions exhibit characteristic piasmon bands for the Au- and Ag-day suspensions at 520 nm and 410 nm respectively as shown in Fig. 3. In the cases of Pt and Pd, the characteristic absorption band for the precursor s around 260 to 280 nm was absent thereby confirming the formation of Pt and Pd nanoparticles. 7,18 TEM images of the aminoday-metal nanoparticle composites deposited on a carbon coated copper grid are shown in Fig. 4. The histograms show the average particle sizes to be around 3.5 and 5 nm respectively in the cases of Au and Ag nanoparticles. We could see the layered arrangements in the cases of Pt and Pd with the interspacing of 1.5 nm commensurate with the bilayer arrangement of aminoclays (see top right inset of Fig. 4b).

Lead Acetate TS Dissolve 9.5 g of clear, transparent crystals of lead acetate [Pb(C2H302)2-3H20] in sufficient recently boiled water to make 100 mL. Store in well-stoppered bottles. 

Materials such as colorants can range from highly transparent through varying amounts of translucency to opaque. Dyes will be truly transparent. Plastics themselves can be transparent (water clear) to opaque. These varying opacity levels of colorants and plastics are major factors considered when determining colorant formulations for plastics products. 

In an experiment you take one gram of poly(Ar-isopropylacrylamide) (PNIPA) and dissolve it in 100 grams of water at room temperature in a sealed glass vial. You notice that it is a perfectly clear (transparent) solution. 

Water is a clear, transparent liquid, colorless in thin layers. Thick layers of water have a bluish-green color. 

Procedure. The carbomer is dispersed in the glycerine and water, and a solution of the 2-ethylhexylamine in ethanol is added to the water solution with mixing until a clear transparent gel is formed. 

A) Preparation of Phenol-Formaldehyde Resin. Place in an eight-inch tube 5 g of phenol, 15 ml of 40 per cent formaldehyde solution, and 3 ml of concentrated aqueous ammonia. Heat the tube for a few minutes with a small flame until the solution becomes opaque and milky. Cool the tube, and decant the upper layer, retaining the lower viscous material. Add 10-12 drops of acetic acid to the viscous material and heat in a water bath at 60 for thirty minutes. Pour some of the liquid into a glass tube 6 mm in diameter and 100-150 mm in length, sealed at one end. Place the remainder in a small clean test tube made of thin glass. Label both tubes, and place in oven at 80° until the next laboratory period. Break the tubes cautiously to obtain the clear transparent resin. 

Microemulsions are clear (transparent and translucent are also used in the literature), thermodynamically stable, isotropic liquid mixtures of oil, water, and surfactant, frequently in combination with a cosurfactant. The aqueous phase may contain salt(s) and/or other ingredients, and the oil may actually be a complex mixture of different hydrocarbons and olehns. In contrast to ordinary emulsions, microemulsions form upon simple mixing of the components and do not require high shear conditions generally used in the formation of ordinary emulsions. Microemulsions tend to appear clear due to the small size of the disperse phase. However, clear appearance (transparency) may not be a fundamental property. Sometimes microemulsion may not look clear to the naked eye in the case where dark viscous oil exists. The solution may not be purely transparent because it contains aggregates of micelles. Quite often, we still use these terms, even in this book. Probably we should simply use the term homogeneous solution. 

Clear, viscous liquids Or white solids which dissolve in water forming transparent solns. Sol in many organic solvents. Readily sol in aromatic hydrocarbons. Only slightly sol in aliphatic hydrocarbons. Do not hydrolyze or deteriorate on storage, will not support mold growth. Polyethylene glycols are compds of low toxicity Smyth et al, J. Am. Pharm. Assoc., Sci. Ed. 39, 349 (1950). Toxicity data (PEC 400) W. Bartsch et aL, Arzneimittel-Forsch. 26, 1581 (1976). 

The resulting highly-alkylated ethylcellulose is a powdery flocculent substance which is soluble in a number of organic solvents, e.g., chloroform and alcohol, and these solutions give clear, transparent, flexible, and water-resistant films when evaporated. 

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