Rocky Hill, Connecticut -- Henkel is offering a new high-performance polyurethane adhesive that it claims "prevents crack propagation on wind blades and delivers excellent long-term structural integrity on turbine assemblies."
Henkel also says its Macroplast UK 1340 is the first polyurethane adhesive approved by Germanischer Lloyd (GL). The adhesive also cures rapidly at room temperature, reduces production costs, and shortens production cycles by 15 to 30 percent, says Henkel.
GL requirements primarily relate to an adhesive's tensile shear strength, resistance to ageing, creep behaviour and glass transition temperature. Macroplast UK 1340 has a tensile shear strength, exceeding 20 MPa at -40 to +80°C and a Tg of 65°C and higher.
In tests, Henkel said the adhesive shows superior dynamic fatigue strength, which allows wind blades to handle deflection, dynamic load and stress on the adhesive bond line and reduces the risk of stress cracking.
According to Henkel, the bonding agent passed a four month test by the Fraunhofer Institute for Wind Energy and Energy System Technology IWES in which a 40-m Enercon blade was subjected for four months to stresses and strains that would normally occur over 20 years.
Henkel says the joints passed all static and dynamic load tests specified in the IEC 61400-23 standard to determine the rated load and fatigue behaviour of blades.
The test criteria specified for approval of wind energy plants were met without any problems, the company adds, noting that Enercon specifications were also satisfied in this test.