Polyethylene stored

The acryhc esters may be stored in mild or stainless steel, or aluminum. However, acryhc acid is corrosive to many metals and can be stored only in glass, stainless steel, alurninum, or polyethylene-lined equipment. Stainless steel types 316 and 304 are preferred materials for acryhc acid. 

Because hydrogen fluoride is extremely reactive, special materials are necessary for its handling and storage. Glass reacts with HF to produce SiF which leads to pressure buildup and potential mptures. Anhydrous hydrogen fluoride is produced and stored ia mild steel equipment. Teflon or polyethylene are frequently used for aqueous solutions. 

The high purity anhydrous copper(II) fluoride must be stored ia a tightly closed or sealed container under an atmosphere of argon. The dihydrate may be stored ia polyethylene-lined fiber dmms. The ACGIH (1992—1993) adopted toxicity value for copper as Cu is 1 mg/m, and for fluorides a F , 2.5 mg/m. ... 

The 1993 price of high purity anhydrous nickel difluoride was 0.55 /g in 100- or 250-g quantities. Small quantities are stored and shipped in polyethylene bottles, whereas large amounts are shipped in fiber board dmms with polyethylene liners. 

Titanium trifluoride can be stored in tightly closed polyethylene containers for several years. Shipping regulations classify the material as a corrosive sohd and it should be handled in a fully ventilated area or in a chemical hood. The ACGIH adopted toxicity values (1992—1993) for TiF is as TWA for fluorides as F 2.5 mg/m. ... 

Hexafluorozirconic acid [12021 -95-3]], H2ZrP, is formed by dissolving freshly prepared oxide, fluoride, or carbonate of zirconium in aqueous HP. This acid is produced commercially in a concentration range of 10 to 47%. The acid can be stored at ambient temperatures in polyethylene or Teflon containers... 

Dry oxahc acid is packed and sold in polyethylene-lined, multilayered 25-kg paper bags or in polyethylene-lined 300—600-kg PVC flexible containers. It should be stored in a cool, dry, ventilated place. For storage of its solutions at ordinary temperature, 316 stainless steel is often used as a constmction material. 

Magnesium methylate is sensitive to air and moisture, decomposing to magnesium hydroxide, carbonate, and methanol. It can be stored for one year in polyethylene bags under nitrogen or argon. 

Alkoxides should be stored under cool, dry conditions. The soHds are packed in polyethylene bags under nitrogen or argon that are shipped in dmms with foam mbber gaskets. For the Hquid alkoxides steel dmms are used, usually with a polyethylene liner. 

For shipping purposes, the ampul is placed in aluminum foil or polyethylene bags. The wrapped ampul is packed in a metal can and surrounded by an inert filler material such as vermiculite. These precautions are necessary in order to minimize the chances of ampul breakage during shipment. Most mbidium compounds, however, can be shipped as nonhazardous materials. These compounds are usually stored in glass or polyethylene botdes. 

Succinic acid and succinic anhydride are sold in 25-kg net polyethylene (PE) bags having cardboard box protection for the anhydride, in 70-liter (50-kg net) fiber dmms, and in 55-gaHon (275-lb 125-kg net) dmms. The two products must be stored in a fresh, dry, ventilated area. Succinic anhydride must be carefully protected from moisture during transportation and storage to avoid hydrolysis to succinic acid. 

Shipment and Storage. The weight per gallon is 5.6 kg. MSG is shipped and stored in 55-gaHon (0.208 m ) steel dmms or 5-gaHon (0.02 m ) steel pads with a polyethylene liner. Anhydrous MSC is also corrosive toward titanium, titanium—palladium, and zirconium as measured in metal strip tests at 50°C. It is classified as a corrosive Hquid. 

Thioglycohc acid is stored ia reiaforced polyethylene or polypropylene tanks or contaiaers. It is advisable to keep thioglycohc acid at low (<10° C) temperature to slow down self-esterification. The same care must be taken with dmms or tank tmcks. Dmms are made of polyethylene or polyethylene-liaed steel. For transport, thioglycohc acid is classified as a corrosive and toxic hquid. The handling of thioglycohc acid requires the usual precautions observed for strong acid and corrosive chemicals. 

Plasticized PVB interlayer is hygroscopic. In addition, Ts are in the neighborhood of 30°C thus, interlayer tends to adhere to itself, or block, when roUs or stacks of cut blanks are stored at ambient conditions. For these reasons handling and shipping must be carried out under controUed humidity and at temperatures weU below the sheet s T. Precut interlayer blanks and roUs are usually stored or shipped refrigerated (3—I0°C), and when roUs need to be stored or shipped at ambient conditions, the sheet is interleaved with a thin sheet of nonadhering plastic such as polyethylene. 

Liquid Eeeders. Liquid feeders employ positive-displacement metering pumps for adding aqueous solutions of sodium or calcium hypochlorite. The feed solutions are typically stored in polyethylene tanks of various capacities up to about 0.19 m (50 gal). 

Polyethylene. Low pressure polymerization of ethylene produced in the Phillips process utilizes a catalyst comprised of 0.5—1.0 wt % chromium (VI) on siUca or siUca-alumina with pore diameter in the range 5—20 nanometers. In a typical catalyst preparation, the support in powder form is impregnated with an aqueous solution of a chromium salt and dried, after which it is heated at 500—600°C in fluid-bed-type operation driven with dry air. The activated catalyst is moisture sensitive and usually is stored under dry nitrogen (85). 

Heavy metal contamination of pH buffers can be removed by passage of the solutions through a Chelex X-100 column. For example when a solution of 0.02M HEPES [4-(2-HydroxyEthyl)Piperazine-l-Ethanesulfonic acid] containing 0.2M KCl (IL, pH 7.5) alone or with calmodulin, is passed through a column of Chelex X-100 (60g) in the K" " form, the level of Ca ions falls to less than 2 x 10" M as shown by atomic absorption spectroscopy. Such solutions should be stored in polyethylene containers that have been washed with boiling deionised water (5min) and rinsed several times with deionised water. TES [, N,N, -Tetraethylsulfamide] and TRIS [Tris-(hydroxymethyl)aminomethane] have been similarly decontaminated from metal ions. 

Triacetin resistance is especially critical when filter tips are made in one location, stored, and then shipped to another location. For these operations, polyethylene-based adhesives are used because of their low polarity and therefore excellent resistance to triacetin. Where filter plugs are attached at the same location shortly after production, EVA-based adhesives are suitable and preferred. Both types of adhesives use low odor, clean tackifiers such as hydrogenated hydrocarbons or pure monomer resins (typically a-methylstyrene based). Rosin, rosin esters, and phenol-containing tackifiers are not acceptable. EVA-based adhesives use a higher level of wax (about 1 /3 of the formula) than polyethylene-based adhesives (5-20% wax) due to the lower crystallinity and slower set of EVA vs. PE. Application viscosities are 2000-5000 cP. 

Such an experience with one plastic, PVC, makes it doubly important to carefully examine any plastic to be used with a food product. The basic question to be answered is Does the plastic container provide adequate protection to the food product during the entire life cycle of the container Adequate protection of a food product in a polyethylene container implies that there is no undesirable change in the chemical content of the food during storage in the container. Thus, our study is concerned with the ways in which food products can change when stored in polyethylene containers. 

Figure 7. Five-gallon, high density polyethylene bottle as used and as shipped and stored, in a corrugated carton. Used for shipping various flavor concentrates, such as grape, orange, and root beer.

Red Meat. The in-store wrapping of fresh meats is another packaging system with interesting compatibility requirements. If red meats are packaged in a heavy polyethylene film, 2 mils thick for example, the meat will turn dark. If, however, a % mil vinyl film with high oxygen trans-... 

Adventitious surfactants also have a marked effect on the mechanism of coalescence. In studying the coalescence of curved water surfaces, Lindblad (L8) used aged distilled water that was stored for about 30 h in a polyethylene bottle opened to the air through a narrow polyethylene tube inserted in the water. He found that if fresh distilled water (water exposed not longer than 1 h to the air) was used, the delay time in coalescence was approximately half as long. Consequently, he concluded that this difference is due to some form of contamination which settled into the water or onto the water surface. 

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