Containers plastic

In a plastic container the chemist dissolves her golden yellow freebase oil into some DCM, ether or ethanol. The chemist then starts a steady dripping of the sulfuric acid into the HCl/salt and white, puffy HCI gas will start to exit the glass rod or pipette which is at the end of the hose. That tip is then plunged into the sol-vent/freebase solution to bubble the gas through the solvent. 

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. 

The procedure specifies that the standard and sample solutions should be stored in plastic containers. Why is it not a good idea to store the solutions in glass containers ... 

The General Tests and Assays. This section of the USP gives methods for tests that are general in nature and apply to a number of the substances. Procedures are iacluded for such tests as heavy metals, melting point, chloride, sulfate, sterility, bacterial endotoxins, and pyrogens. Also iacluded are descriptions of various analytical techniques, such as spectrophotometry, chromatography, and nmr, and descriptions of tests to be used on glass or plastic containers, mbber closures, etc. 

Cobalt difluoride [10026-17-2] C0F2, is a pink solid having a magnetic moment of 4, 266 x 10 J/T (4.6 Bohr magneton) (1) and closely resembling the ferrous (Fep2) compounds. Physical properties are Hsted in Table 1. Cobalt(II) fluoride is highly stable. No decomposition or hydrolysis has been observed in samples stored in plastic containers for over three years. 

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. 

Lead-loaded plastics containing up to 90 wt % lead are used in x-ray protection as aprons and temporary shields in medical and industrial appHcations. Leaded glass is used to attenuate radiation where viewing the ongoing process is requited. Steel-jacketed containers fihed with lead or special lead containers are used to transfer, ship, and store fuel rods, radioactive sources, and nuclear waste. Lead is generahy used where space is limited. 

The future for mica is ia the speciaUty plastic market, eg, as a molecular barrier ia plastic containers and ia plastic automobile parts. 

Chemical Applications. Chemical analysis can be conveniently accelerated by heating of samples in small pressure-tight plastic containers (168-171). 

Rotational Molding. Large containers and some toys are manufactured with a specialized technique caHed rotational mol ding. A rotational mol ding machine contains several large metal molds that can be rotated in two perpendicular planes. A load of fine LLDPE particles is introduced into each mold, and the mold assembly is transferred into an oven. Inside the oven, heated molds rotate at speeds ranging from 10 to 40 rpm. The polymer powder melts and is uniformly distributed on the internal surface of each mold. After the container is formed, the mold assembly is removed from the oven and cooled at which point the plastic containers are removed. 

Increasingly, plastics are being used as parenteral packaging (qv) materials. Plastics such as poly(vinyl chloride), polyethylene, and polypropylene are employed. However, plastics may contain various additives that could leach into the product, such as plasticizers (qv) and antioxidants. PermeabiUty of plastics to oxygen, carbon dioxide, and water vapor must be tested in the selection of plastic containers. Furthermore, the plastic should withstand sterilization. Flaking of plastic particles should not occur and clarity necessary for inspection should be present. 

To complete the assembly of a cell, the interleaved electrode groups are bolted to a cov er and the cover is sealed to a container. Originally, nickel-plated steel was the predominant material for cell containers but, more recently plastic containers have been used for a considerable proportion of pocket nickel-cadmium cells. Polyethylene, high impact polystyrene, and a copolymer of propylene and ethylene have been the most widely used plastics. 

In the past few years many changes have occurred in the packaging materials utilized for distilled spirits. Traditionally, distilled spirits have been packed primarily in glass containers of approved ATF sizes. Over the last 5—10 years, plastic containers, primarily poly(ethylene terephthalate) (PET), have been utilized by increasing numbers of distillers. Because of environmental concerns, the last two years have seen a change back to glass on some of these package sizes. However, the 50 mL miniature bottie continues to be primarily packed in PET plastic containers. 

The usual containers for shipping are glass for small quantities, and steel cans, dmms, or tank cars for bulk items. Over a period of time, moisture passes through the walls of some plastic containers. If this occurs, the more hydrolytically unstable borate esters may hydroly2e. Thus caution should be used when storing borate esters in plastic. In addition, shipping in metal cans or dmms is not acceptable where hydrolysis can lead to a corrosive product, such as a halogenated alcohol. 

Solution sodium chlorite is shipped by producers and distributors in specified plastic containers, plastic dmms, tote tanks, isotainers, and tank tmcks. Dry product is shipped in 45.36 kg, 50 kg, and 80 kg capacity dmms in the United States. Sodium chlorite is not authorized for bulk transport as a soHd. 

Tissue Conditioners. Tissue conditioners are gels designed to alleviate the discomfort from soft-tissue injury, eg, extractions. Under a load, they exhibit viscous flow, forming a soft cushion between the hard denture and the oral tissues. The polymer in tissue conditioners is often the same as that used for resilient liners. The liquid is a plasticizer containing an alcohol of low volatility (219,220). 

Some of the more obvious sources of contamination of solvents arise from storage in metal drums and plastic containers, and from contact with grease and screw caps. Many solvents contain water. Others have traces of acidic materials such as hydrochloric acid in chloroform. In both cases this leads to corrosion of the drum and contamination of the solvent by traces of metal ions, especially Fe. Grease, for example on stopcocks of separating funnels and other apparatus, e.g. greased ground joints, is also likely to contaminate solvents during extractions and chemical manipulation. 

Fig. 24.4. (a) Vacuum forming is good for making simple shapes out of sheet. (b) Blow moulding is used to make plastic containers. 

Dmms comprise metal, lined metal or plastic containers with capacity up to 60 gallons (227 L) and are the largest containers considered in the following sections. Metal and plastic-lined metal drums can have either fixed or removable heads. It should always be ensured that dmms are sealed prior to... 

Filling and Emptying Small Nonconductive Containers Subject to capacity limitations described in 5-8.4 it is common to handle flammable liquids in small glass or plastic containers. The following should be considered for frequent indoor liquid transfers of about 0.5 L (approxi-... 

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