Advances reported in alloying and compatibilization.
Developments in thermoplastic alloys and compatibilization technology, unveiled at the recent Compalloy '91 conference in New Orleans, include a new polymethylpentene with glass-fiber coupling agents, a polycarbonate/nylon alloy, an acrylic-imide copolymer used to modify nylon 6 for blow molding, and an experimental blend of liquid-crystal polymer and PTFE.
The fourth annual conference, sponsored by Schotland Business Research Inc., Princeton, N.J., once again provided a forum for discussion of recent advances in the dynamic field of proprietary compatibilization technology and polymer modifiers (see PT, May '90, p. 25). New alloys and compatibilizers are widely considered to be the vanguard of polymer technology research for the 1990s.
A new developmental grade of Crystalor polymethylpentene (PMP), which features 30% glass reinforcement and a proprietary coupling agent, is being introduced by Phillips 66 Co., Bartlesville, Okla. William H. Beever, supervisor of Phillips' alloys, blends and compounds section, says mechanical properties of the new Crystalor HBG-30HP have been enhanced through a proprietary coupling agent, which promotes improved fiber/matrix adhesion. Beever says the glass-reinforced polyolefin fills a cost/performance niche between polypropylene and nylon, and will be priced around $2/lb tl.
The new compound is designed mainly for injection molding. The neat resin's inherently high clarity makes grades with low glass levels suitable for applications such as containers and vessels that require translucence as well as mechanical strength, heat resistance, and the chemical resistance of a polyolefin, according to Beever.
Crystalor HBG-30HP has a processing window of 500 to 600 F. Flow and molding characteristics, which are still being fine-tuned through final development efforts, are expected to be similar to PP. Properties are shown in the accompanying table.
Phillips also is developing a new higher strength coupled version, Crystalor HBG-40HP, with 40% glass. Though it's not yet commercial, Beever says it will provide mechanical properties approaching those of engineering thermoplastics. In addition, Phillips is working on impact-modified Crystalor grades, designed for toughness at down to -20 F.
New details on the formulation of alloys that combine the thermal resistance, dimensional stability and mechanical properties of polycarbonate with the chemical resistance, electrical properties, and processing advantages of nylon, have been unveiled by D&S Plastics International, Troy, Mich., a joint venture of Dexter Corp. and Solvay Polymers, whose main compounding location is the Grand Prairie, Texas, plant formerly belonging to Dexter Plastics. Dexter has licensed this material technology in Japan, and is now seeking additional licensees in the U.S.
The Dexcarb alloy series, first introduced in 1986, is created by the compatibilization of approximately equal amounts of polycarbonate and nylon 6 or 66 (see PT, Sept. '86, p. 12; June '87, p. 11). According to Khemchand J. Nangrani, director of technology, various combinations of three compatibilizing agents are used at 2-20% total levels: thermoplastic polyurethane block copolymer, polyetherimide (GE's Ultem), and an unnamed maleated thermoplastic elastomer. Twin-screw extruders are used in making the alloys.
PHOTO : Twin micrographs show improved fiber/matrix adhesion in Phillips' new glass-coupled Crystalor PMP (right), vs. an uncoupled PMP/glass system (left).
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|Title Annotation:||thermoplastic alloys|
|Author:||Gabriele, Michael C.|
|Date:||Apr 1, 1991|
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