Bayer Material Science has developed a class of polyurethane-based composites for use in large windmill blades.
The company said it developed the class of stronger composite materials in response to the wind power industry’s move toward developing and manufacturing longer, larger, and more productive blades.
Bayer details the results of the development of the low-viscosity, long-gelling polyurethane in a paper published by Dr Usama Younes, principal scientist with Bayer, and Frank Bradish, a researcher with Molded Fibre Glass Research Company.
The characteristics of the newly introduced Baydur resin infusion polyurethane systems were compared against those of epoxy- and vinyl-ester-based composites.
Peter Emrich, Moulded Fibre Glass’s vice-president of technology, told The Engineer: ‘High-fibre volume polymer composites can be brittle and subject to failure from out of plane stresses. However, polyurethane resins are very tough.’
He said the polyurethane composite has excellent fatigue performance, which makes it particularly appealing for use in large wind turbine blades.
Emrich added the work completed by Bayer shows that polyurethane composites have similar or better properties to epoxy and can cure faster.
He said: ‘Faster cure allows for shorter cycles, more output, lower costs. Also the polyurethane has very good coupling to carbon and polymer fibres allowing broader use of these composites.’
The project focused on megawatt-class wind blades but Emrich believes the results could be applied to structural elements in smaller parts, produced in high volume, such as those found in transportation vehicles and sporting goods.
Bayer said that the polyurethane composites are environmentally friendly as they contain low-to-no volatile organic compounds and use sustainable raw materials from renewable resources.