Diamond orifices may cut fiber costs Synthetic fiber producers use orifices called spinnerets to extrude the filaments of polymer that eventually are woven into fabrics such as polyester and nylon. But spinnerets eventually wear out from the severe conditions of high temperature and pressure and extrudate abrasiveness they are subjected to. Fiber makers lose valu able production time periodically re placing worn-out units. Now Megadiamond Corp., Provo, Utah, claims to have come up with a remedy to the problem that it says costs synthetic fiber makers millions of dollars annually in lost production. The firm believes that spinnerets made from a sintered polycrystalline diamond material are the an swer. Recent tests, the company says, show the diamond material to have great promise. According to Megadiamond president Bill J. Pope, "Comparison tests with Megadiamond involving all aspects of synthetic fiber processing—principally wear resistance and chemical inertness— have been successful, so we are very op timistic. We could have a prototype polycrystalline diamond spinneret ready for field testing within six months." In one series of tests, for example, says the firm, a polycrystalline diamond nozzle showed "no appreciable wear" after 50,000 psi of water was pumped through
it for 19 hours. By comparison, a similar tungsten carbide nozzle "deteriorated significantly" after six hours under the same conditions. The Megadiamond process produces polycrystalline diamonds by sintering finely divided (about 1 to 5 micrometer) diamond particles into a single shape. Diamond material can be either natural or synthetic, says Pope, and the finished material "won't be any more expensive than platinum," another commonly used material for making high-pressure orifices (particularly for fiber extrusion). Once formed, the polycrystalline diamonds can be cut and shaped with lasers, electrodischarge machining, and diamond brazing techniques. He says that a poly crystalline diamond orifice likely will outlast other materials about 60 to 100 times in high-pressure applications. And applications of the new material aren't limited to fiber extrusion. For ex ample, high-pressure water cutting of coal seams is feasible using diamond nozzles. High-temperature wire drawing (extru sion) also is likely. So far, Pope concedes, synthetic fiber producers haven't shown interest in the diamond spinneret, but this is probably because it is still a relatively new inven tion. Consequently, several fiber pro ducers aren't yet ready to comment about the material until they have had a chance to take a look at it under operating con ditions. D
Introducing Gulf PA-18. I f s a unique new polymer thaf s both hydrophobic and hydrophilic. -CH—CH2—CH-
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If you can use a polymer that's hydrophobic as well as hydrophilic, consider Gulf's new PA-18 poly anhydride resin. PA-18's long hydrocarbon side chain provides hydrophobic character to the otherwise highly polar structure of this low molecular weight, linear copolymer. PA-18 is soluble in aqueous hydroxides 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: D.L. Burdick, Specialty Chemicals, Gulf Oil Chemicals Company, P.O. Box 3766, Houston, Texas 77001. Or call us, at 713/226-2889.
Binder cuts wind losses of coal, other minerals Wind erosion can cause substantial losses of minerals in transit or in outdoor storage, Nalco Chemical points out. To reduce such losses, the firm has introduced Nalco 8820, a chemical binding agent. The concentrate, diluted with water and sprayed on the mineral, dries to form an insoluble crust that binds the mineral particles together, preventing wind losses and also eliminating dust problems. In a recent test, aluminum foil was buried 2 inches deep in loaded coal cars. In some cars the coal was sprayed; in others it wasn't. After shipment, the foil was exposed in the untreated cars, still buried in the treated cars. Thus, Nalco concludes, the binder works.
Specialty Chemicals Gulf Oil Chemicals Company
July 12, 1976 C&EN
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