by Reinforced Plastics magazine staff
The newly qualified prepregs use Hexcel’s HexPly M9.6G and M19G epoxy resin systems. Both are MDA free and fully compliant with Europe's REACH regulations.
The Hexcel HexPly M9G is a standard cure product. HexPly M19G cures in 15-20% less time while having the same handling and mechanical properties.
Both prepregs are suitable for shells, spars and the root end of wind turbine blades.
With the faster curing HexPly M19G less energy is required to cure the prepreg and there are potential savings in mould costs as less expensive tooling resins and coatings can be used, along with a cheaper tooling support system.
Both prepregs are constructed using Hexcel’s patented Grid Technology where the grid assists in removing air during the vacuum bag process and ensures that the void content in the final unidirectional carbon laminate is very low.
The GL Statement of Approval for Hexcel’s prepregs means that wind blade manufacturers and designers can select certified MDA-free carbon fibre/epoxy materials that have been approved for blade construction following rigorous testing and data analysis.
Hexcel is a major supplier of prepregs and composite materials to the wind energy industry from dedicated plants in Austria, China and the USA.
The company says that wind blade manufacturers are increasingly turning to carbon fibre composites for their superior mechanical properties, high strength and modulus at lower weight than alternative technologies, all requirements for the very long rotor blades used in multi-Megawatt wind turbines. In unidirectional (UD) prepregs the carbon fibres are all aligned in a single direction without the use of any stitching yarn and impregnated with an exact quantity of resin to provide optimal strength and stiffness exactly where required in the structure.
