GULF PA-18. ITS A UNIQUE POLYMER THAT'S BOTH HYDROPHOBIC HYDROPHIUC. -CH—CH2—CHCH,),
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Plastic sheets stand up to brine filtration service A sand filtration bed, supported by porous plastic sheets, undergoes backwashing at Weyerhaeuser's chlorine plant in Longview, Wash. Built to withstand the corrosive service of cleaning up saturated brine at 140° F and a pH of 11.5, the filter has provided seven years of continuous service. The plastic sheets—made by Glasrock Products of polyethylene with a controlled porosity structure of omnidirectional, interconnecting pores—replaced conventional aluminum oxide filter plates in the rebuilt filter. The binder that cemented the ceramic plates together had been subject to attack by the brine solution. The filter was originally rebuilt with a double layer of thin porous plastic sheets; these have now been replaced with new 0.5-inch thick sheets.
intensity of the longer UV waves and appear beneficial in curing TiCVfilled materials. An alternate system is the pulsed UV lamp, which yields much higher peak intensity but lower average intensity than other UV sources. According to Knappe, the attractiveness of radiation curing has been largely attenuated by indirect economic effects from the oil embargo of 1973. For example, a major investment barrier has all but stopped the building of new EB installations. No EB units are being built unless the technical innovations that EB technology represent are paramount. Resistance to the high unit prices for radiation-cured materials, though sometimes a problem, usually can be overcome upon realization that the materials are much more extensible than conventional materials. Radiation-cured systems are generally quite competitive in Europe.
Demand for radiation-cured materials in Europe will be particularly high in metal decoration, wood coatings, and such flexible plastic materials as flooring products. One obstacle to growth of radiation curing, Knappe says, may be occupational safety problems, particularly those relating to the handling of monomers. Health hazards attributed to the radiation itself have disappeared with the use of properly designed equipment. Monomer handling problems also can be overcome without great difficulty, but the perceived problem still persists. If the energy crisis of the past few years has made the investment climate for radiation curing somewhat speculative, it has also increased the importance of process efficiency. In the long term, gains in efficiency may more than offset any other consideration. •
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If you can use a polymer that's hydrophobic as well as hydrophilic, consider Gulfs new PA-18 polyanhydride resin. PA-18's long hydrocarbon side chain provides hydrophobic character to the otherwise highly polar structure of this medium molecular weight, linear copolymer. PA-18 is soluble in both aqueous systems and organic solvents. It becomes hydrophobic upon solvent evaporation. Gulf PA-18 is also extremely reactive. Because of its anhydride groups, PA-18 can offer you a wide range of useful products through reaction with aqueous bases, ammonia, amines, alcohols and epoxides. PA-18 can be crosslinked, too. Only Gulf has PA-18. And it's now available in commercial quantities. Write us for technical information, suggested applications, free one-pound sample and a price list. Write: C. E. Tuttlc Specialty Chemicals, Gulf Oil Chemicals Company, P.O. Box 3766, Houston, Texas 77001. Or call us, at 713/750-3235.
Gulf Specialty Chemicals Gulf Oil Chemicals Company A division of Gulf Oil Corporation
Oct. 23, 1978 C&EN
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