| Less-Polluting Resins for Molding Composite Structures |
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| Army Research Laboratory, Adelphi, Maryland | |
| Jan 31 2008 | |
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Advertisement: Each MFA monomer molecule contains one terminal polymerizable unsaturation site; hence, MFA monomers act as molecular-chain extenders, as do styrene molecules in vinyl ester resins. MFA monomers are attractive as alternatives to styrene in liquid molding resins for several reasons: they have fairly high molecular weights, are nonvolatile, and are derived from renewable sources (plant oils), and the cost of producing them has been estimated to be only slightly greater than that of styrene. (Plant oils have long been used to make polymers, but the use of them to make fatty acid monomers for use as reactive diluents is new.) The molecular structures of the fatty acids incorporated into MFA monomers affect the properties of polymers and composites made from the monomers. In general, as the lengths of fatty acid molecules decrease, viscosities of resins decrease and mechanical properties of polymers and composites become more favorable, but cost is also a factor. Among various MFA monomers, methacrylated lauric acid (MLau) monomers represent a balance among these considerations: they have good resin and polymer properties and low cost. Methacrylated octanoic acid (MOct) monomers cost more than do MLau monomers, but have lower viscosity and their polymer properties are less favorable. In a simplistic approach, one could replace all of the styrene in vinyl ester or unsaturated polyester resins with fatty acidbased monomers. However, the properties of the resulting resins and polymers would be poor, relative to properties of commercial vinyl ester resins and polymers. The approach followed in the present invention — replacing most of the styrene so as to reduce styrene content to between 10 and 25 weight percent — has been found to be a good compromise in that desired resin and polymer properties are retained, while the volatile organic contents of resins, and the corresponding amounts of volatile organic compounds emitted into the atmosphere are reduced by amounts ranging from 50 to 80 percent. This work was done by John J. La Scala, Theresa Glodek, Caroline Lochner, Philip Myers, Steven Boyd, and James M. Sands of the Army Research Laboratory; Xing Geng and Giuseppe R. Palmese of Drexel University; Ashiq Quabili, Stephen Andersen, and John Gillespie, Jr. of the University of Delaware; Ken Patterson, Frank Bruce, Edward Bartling, Charlie Johnson, and Lawrence Coulter of Hill Air Force Base; Roger Crane of the Naval Surface Warfare Center Carderock; and Michael Starks and Jorge Gomez of the Red River Army Depot. This Brief includes a Technical Support Package (TSP).
Less-Polluting Resins for Molding Composite Structures (reference ARL-0026) is currently available for download from the TSP library. Login first to download.
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