Glass labelling

The NFPA code is represented in a diamond containing 4 sectors, respectively toxicity, inflammability, reactivity and special risks . A coloured code that will appear on glass labels, at the back of transport vehicles, room doors etc enables the danger to be better noted. It is used by American companies although some French companies have also adopted it and it appears to be an efficient device. 

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. 

After each filtration is complete, carefully remove the filter paper from the funnel with the help of a spatula, and place the filter paper and precipitate on the same watch glass labeled with your name. Dry the filter papers and precipitates by heating them either on a steam bath, with a heat lamp, or in an oven (Laboratory Methods M), as designated by your instructor. Continue to parts B and/or c while your samples are drying. 

Remove the aspirator hose, take apart the Gooch filter assembly, place the Gooch crucible on a watch glass labeled with your name, and dry the Gooch crucible and contents in the oven for about 1 hour at 110°C. Go on to part C while you are waiting for the Gooch crucible and contents to dry. 

Many silver compounds are unstable to light, and are thus shipped ia brown glass or opaque plastic bottles. Silver compounds that are oxidants, eg, silver nitrate and iodate, must be so identified according to U.S. Department of Transportation (DOT) regulations. Compounds such as silver cyanide, which is toxic owiag to its cyanide content, must carry a poison label. However, most silver compounds are essentially nontoxic. 

Bromates represent a potential fire and explosion hazard if heated, subjected to shock, or acidified. They should not be allowed to contact reactive organic matter, including paper and wood. Industrial quantities are packed in fiber dmms with polyethylene liners or in metal dmms. Laboratory quantities are supphed in glass bottles. For shipment, a yellow oxidizer label is required under DOT regulations. 

Commercial ethyl alcohol is shipped in railroad tank cars, tank tmcks, 208-L (55-gal) and 19-L (5-gal) dmms, and in smaller glass or metal containers having capacities of 0.473 L (one pint), 0.946 L (one quart), 3.785 L (one U.S. gal), or 4.545 L (one Imperial gal). The 208-L dmms may be of the unlined iron type. If a guarantee of more meticulous quaUty is desired, the dmms may be lined with phenoHc resin. AH containers, of course, must comply with the specifications of the U.S. Department of Transportation. Both 190 proof and 200 proof ethyl alcohol are considered red label (flammable) materials by the DOT, as both have flash points below 37.8°C by the Tag closed-cup method. 

We present here a simple experiment, conceived to test both the reptation model and the minor chain model, by Welp et al. [50] and Agrawal et al. [51-53]. Consider the HDH/DHD interface formed with two layers of polystyrene with chain architectures shown in Fig. 5. In one of the layers, the central 50% of the chain is deuterated. This constitutes a triblock copolymer of labeled and normal polystyrene, which is, denoted HDH. In the second layer, the labeling has been reversed so that the two end fractions of the chain are deuterated, denoted by DHD. At temperatures above the glass transition temperature of the polystyrene ( 100°C), the polymer chains begin to interdiffuse across the... 

---