06/05/2012

www.gupta-verlag.de/polyurethanes

New PU systems for larger, yet lightweight wind turbine blades

Current materials are not designed to withstand these increased demands. Lighter weight composite materials with increased stiffness and enhanced fatigue endurance properties offer a promising solution. Bayer MaterialScience LLC's newly developed class of polyurethane systems offer stronger, tougher polymers ideal for producing polyurethane composites suitable for manufacture of large parts by vacuum infusion. The company's Baydur polyurethane system possesses low-viscosity and long-gelling properties. Comparative testing against epoxy and vinyl ester-based composites reveals the Baydur polyurethane system provides several key advantages, including: Superior tensile fatigue, interlaminar fracture toughness and fatigue crack growth;Ultra-low volatile organic compounds (VOCs);Faster infusion time;Use of sustainable raw materials from renewable resources. Bayer Principal Scientist Dr. Usama Younes has shared the results of a recent study, funded in part by a Department of Energy (DOE) grant that details the development of this Baydur polyurethane system during two presentations. His first presentation, "Polyurethane structural components for wind turbine blades," was during the Sandia National Laboratories Wind Turbine Blade Workshop, held on 1 June 2012 in Albuquerque, NM, USA. He also presented during a poster reception at the American Wind Energy Association WindPower 2012 conference, held 3 - 6 June 2012 in Atlanta, GA, USA. As part of his presentations, Dr. Younes explained tests comparing properties of incumbent epoxy and vinyl ester resin systems with a polyurethane resin system. Younes detailed compressive strength tests of polyurethane resins compared with epoxy resins, showing that polyurethane systems are roughly one-third stronger than epoxy resins. Other testing compares polyurethane with unsaturated polyester and indicates that polyurethane composite's impact strength is nearly double that of unsaturated polyester composites. Additional testing also shows that polyurethane-based carbon fibre systems offer enhanced fatigue resistance compared with epoxy resins. Younes also discussed testing that included two sets of long flow, vacuum-infusion experiments designed to compare the flow rates of the different resins, and studies that show a clear trend toward improvement in the fracture toughness of composites from the presence of multi-walled carbon nanotubes. "This research is important across the wind energy value chain, demonstrating that polyurethanes may provide distinct technology advantages that current resins in use would not, especially as the market continues to increase the size of turbine blades," said Sharon Papke, head, Wind Energy, Bayer MaterialScience LLC. "At Bayer we leverage a broad business portfolio to provide solutions to the wind energy market and meet industry needs." Development of the Baydur polyurethane system is the result of a DOE grant (DOE award number DE-EE0001361) for the development of new, stronger composite materials for wind blades. The grant also helped fund additional research comparing the performance of new polyurethane resins systems with those of traditional epoxy and vinyl ester resins used for wind blades. The grant's scope included investigating the effect of carbon nanotubes on the performance of polyurethane, epoxy and vinyl ester composites.

www.gupta-verlag.de/polyurethanes