Bayer conducted tests to compare the properties of epoxy and vinyl ester resin systems with a polyurethane resin system. Two sets of long-flow vacuum infusion experiments were designed to compare the flow rates of the two different resins. The research team also studied the effects on the properties of fiber-reinforced composites by including multi-walled carbon nanotubes.
The team found that the nanotubes helped improve the fracture toughness of the composites. "Incorporation of a small amount of multi-walled carbon nanotubes improves the fracture [toughness] of both polyurethane and epoxy composites by as much as 48 percent," Younes said in a second press release. "The addition of carbon nanotubes is a viable option to improve the strength of wind turbine blades."
The tests were part of a recent study funded in part by a Department of Energy grant for the development of stronger composite materials for wind blades. The grant also helped fund development of the Baydur polyurethane system and will fund additional research comparing the performance of new polyurethane resin systems with those of traditional epoxy and vinyl ester resins used for wind blades.
Bayer has also developed the Baydur Resin Transfer Molding (RTM) custom polyurethane system for making wind turbine root rings and blades, as well as lightweight structural components for the transportation industry. The custom formulation improves process efficiency by offering a faster demold time than epoxy. The wall thickness of parts can be decreased, yet the material is stronger than polyester, resulting in lighter parts that maintain strength.