Flax/acrylic FLOW turbine blade manufactured by in situ polymerisation (ISP) monomer infusion under flexible tooling (MIFT)

A flax fabric reinforced acrylic thermoplastic matrix component has been manufactured as two half blades (front and back respectively) with the parts bonded together with a wood dust acrylic polymer to produce a component with the same thermoplastic polymer used for the composite matrix and the adhesive. The mould profile is for a floating offshore wind (FLOW) turbine blade at scale 1:50. This model represents the NREL 5 MW reference wind turbine. The blades are not scaled geometrically, but instead have been adapted to produce Froude scaled thrust, in spite of much lower Reynolds numbers at reduced scale and when using Froude scaled wind. The trimmed and faired blade weight weighs 395g. The profile surface has small areas of relative dryness, but the extent of the defect is similar to that seen in comparable synthetic fibre reinforced composite mouldings. The wood-filled adhesive appears to foam at some time after mixing: it may be that the exotherm takes the temperature to the boiling point of the monomer .There does appear to be some profile distortion, probably due to MMA vapour acting to soften the unsupported PMMA matrix (as a general rule in chemistry like dissolves like”).