Dow Epoxy, a business unit of The Dow Chemical Company, has introduced the new DOW COMPAXX™ 900 foam core system, which is designed to enable the fabrication of wind blades exceeding 40 meters in length. Dow continues to offer the COMPAXX 700 foam core system for use in wind blades of less than 40 meters.
This latest addition to the COMPAXX line of foam core systems is a structural foam that can help minimize composite weight, which is critical in the production of longer wind blades. The weight savings are made possible by low resin pick-up during fabrication. The foam’s small cell size—up to 100 times smaller than cells in chemical blown foams such as PVC—limits the amount of resin that can fill cut cells at the surface. In addition, the closed cell structure of the material prevents penetration of the resin deeper into the foam. Although resin pickup is low, the inherent ductile properties of COMPAXX 900 produce excellent skin-to-core bonds, and composites made with system exhibit excellent fatigue resistance.
The new foam core system exhibits higher static performance than PVC foam due to the continuous extrusion process used to produce DOW COMPAXX™ 900. The process allows very accurate control of cell expansion and produces cells that are homogeneous in size. The result is a material with optimum mass distribution, uniform cell structure, and consistent wall thickness, factors that enable the new foam to outperform core materials with the same density, such as PVC.
Dow says that DOW COMPAXX™ 900 can be used in the shear web, shell, and in all other parts of wind turbine blades where high performance structural foam is required. It is recyclable, and waste material created during the kitting process or panel manufacturing can be recovered. The foam and final composite material can be recycled by grinding and used as filler in other products. Refer to the Material Safety Data sheet for further details on disposal considerations.
According to Gino Francato, business development manager for Dow’s wind group, “DOW COMPAXX 900 is the product of Dow chemistry and materials science expertise. DOW COMPAXX foam core systems are advanced materials, engineered specifically for wind blade applications. They can reduce fabrication costs and improve wind blade mechanical performance, which makes them excellent replacements for PVC, SAN, and PET, as well as balsa.” Learn more at www.dow.com.