CONTROLLING THE REACTION RATE OF ANIONIC POLYAMIDE-6 FOR VACUUM INFUSION OF COMPOSITE WIND TURBINE BLADES

摘要

In order to manufacture large thermoplastic composite wind turbine blades with an otherwise fast reacting anionic polyamide-6 casting resin, the reaction rate has to be decreased to accommodate for the long mould filling times associated with the vacuum infusion process. This paper discusses three potential methods to accomplish this. The first method, reduction of the amount of initiator in the resin formulation, is not an option due to partial deactivation caused by impurities on the fiber surface. The second method, reduction of the polymerization temperature, is not very effective and, more importantly, significantly influences the final polymer properties. The choice of a suitable activator-initiator combination, the third method, is by far the most effective. Using a difunctional carbamoylcaprolactam activator in combination with a caprolactam magnesium bromide initiator results in a two-step reaction mechanism. In the initial slow step infusion of the fibers can take place, whereas in the subsequent faster step the final curing takes place leading to demolding.