Polyethylene Sheet

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

An aluminum alloy cooling water conduit section was removed from a machine that made polyethylene sheeting. A large hole had formed just below a in. (1.9 cm) cooling water orifice. The designed orifice is shown in Fig. 8.11, with the elliptically shaped corroded hole just below. 

Much effort has been expended to try and produce flat-top foams. In one process polyethylene sheets placed along the side-walls of the trough rise with the foam. In another technique the reactants are metered from the mixing head into a fixed trough in which partial expansion takes place. The foaming material is then drawn over a weir by a moving band of paper and then drawn down a slope so that the top surface maintains a constant level as the material expands. 

Slip membrane serves to reduce friction between the slab and sub-base to minimize subsequent slab cracking. This is normally a polyethylene sheet. It may also serve as a damp-proof membrane ... 

Some use has been made in the water industry of loose envelopes of polyethylene sheeting and with the increasing lengths of submarine pipeline requiring heavy concrete coatings for reducing buoyancy, the use of a heavily filled bituminous coating is projected. 

Laminated tapes In more general use now than pressure sensitive tapes are tapes consisting of polyvinyl chloride or polyethylene films in conjunction with butyl rubber. These tapes are applied with an adhesive butyl rubber primer. Thicknesses of up to 0-75 mm are in use and loose protective outer wraps of p.v.c. or polyethylene sheet are commonly applied. Tape quality control is exercised with reference to ASTM standard test methods and may include water vapour transmission rate and elongation. 

Repairs to the coating are made with either hot-melt polyethylene sticks or polyethylene sheet patches with mastic profiling compounds for small damaged areas. Large repair areas are best treated as for field weld joint coating, where either heat-shrink crosslinked polyethylene sleeves or cold-applied self-adhesive laminate tapes are employed. 

Unpigmented paint samples were brushed onto a potassium bromide crystal or polyethylene sheet (paint film thickness about 5 microns) and stored at controlled relative humidity using saturated salt solutions in closed vessels or a climate controlled room. 

Rasmussen et al. (.15) on reactions of acid chloride groups on the surface of a polyethylene sheet with nucleophiles in aqueous solution, but because of the small number of reacting groups, highly sensitive spectroscopic techniques had to be used to follow the process. 

Due to difficulties often encountered in sealing subfloors and insulating pipes in crawlspace houses, which rarely have a poured floor slab, another radon-resistant alternative that can be applied after construction should be considered. This mitigation technique is a variation of the successful SSD methods used in basements. Polyethylene sheeting is often used as a moisture barrier applied directly over the soil in crawlspaces. The polyethylene sheeting can be used as a gastight barrier that forms a small-volume plenum above the soil where radon collects. A fan can be installed to pull the collected soil gas from under the sheeting and exhaust it outside the house. 

The wide-width polyethylene sheets should be set directly on the earth in a way that produces at least 1-ft overlaps. Some field applications have included a bead of caulking to seal between sheets of... 

Egley GH (1983) Weed seed and seedling reduction by soil solarization with transparent polyethylene sheets. Weed Sci 31 404-409... 

Numerical and experimental studies. Soil Sci 131 82-87 Mahrer Y, Naot O, Rawaitz E, Katan J (1984) Temperature and moisture regimes in soils mulched with transparent polethylene. Soil Sci Soc Am J 48 362-367 Malathrakis NE, Loulakis MD (1989) Effectiveness of the type of polyethylene sheet on soil solarization. Acta Hort (ISHS) 255 235-242... 

In his work, Penefsky simply used 1 ml Plastipak tuberculin syringes fitted with porous disks cut with a cork borer (0.193 inch inside diameter) from polyethylene sheets (1.5 mm thick, 70 micrometer pore size) available from Bolab, Inc. (Deery, NH). Note The rubberized plungers of most syringes frequently contain lubricants, and these agents may bind to enzymes or they may dissolve and contaminate some enzyme preparations. 

Fig. 16. Time-resolved small-angle X-ray scattering patterns from polyethylene sheet recorded during stretch (12 mm/min, 32% stretch/min) in the horizontal direction. An exposure time for each pattern was 1 s. Intervals between exposures were 70 s. An X-ray wavelength was 0.155 nm...

An expl powa contg NGu 9 7, Amm Nitrate 77.7, starch 11.6 and w 1%, is applied to polyethylene sheet overlaid stainless steel sheet and detonated from one end with a percussion cap)... 

Gel support sheet (e.g., porous polyethylene sheet, Curtin Matheson)... 

The optional porous polyethylene sheet is hydrophobic, and it is difficult to get water or buffer into the pores. Be sure to hydrate or wet it properly by spraying water under pressure through the sheet or by submerging the entire polyethylene sheet in methanol and then submerging in high-purity water. 

Fill the transfer tank with lx transfer buffer. Submerge the gel cassette holder, fiber pads, and polyethylene sheet (after initial hydration as described in step 1) in transfer buffer. Place them inside the tank or submerge in transfer buffer using a separate tray. 

A sheet of porous polyethylene is preferred as a support because it is rigid and facilitates handling, but filter paper can be used as a simple alternative. If the polyethylene sheet is used, place it with the smooth side up (toward the gel). 

Figure B3.2.2 Electroblotting with a tank transfer unit. The polyacrylamide gel containing the protein(s) to be transferred is placed on the smooth side of the polyethylene sheet (or filter paper sheets) and covered with the PVDF membrane and then a single sheet of filter paper. This stack is sandwiched between two fiber pads and secured in the plastic gel holder cassette. The assembled cassette is then placed in a tank containing transfer buffer. For transfer of negatively charged protein, the membrane is positioned on the anode side of the gel. Charged proteins are transferred electrophoretically from the gel onto the membrane.

Fig. 1. Apparent secant modulus (stress/strain) in tension at 0.1% strain and at various sample aspect ratios measured at a strain rate of 10 4s 1. Isotropic polyethylene sheet at 22 °C (sample cross section 1 mm X 3 mm)...

To prevent evaporation, polymerization can be carried out in a closed system, such as an enclosed vessel, or the concrete can be wrapped in polyethylene sheet. Another possibility is carrying out the polymerization under water, which is especially attractive for decreasing monomer loss. The monomer in the specimen is usually not miscible with water so that it has little effect on the properties of the concrete-polymer. 

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