Windmill propeller blade and method of making same

1. A windmill blade which comprises reinforcing fibers in a resin matrix, wherein the matrix is made from a matrix composition which comprises (a) one or more epoxy resins, (b) one or more reactive diluents, and (c) at least one amphiphilic block copolymer which comprises at least two different polyether blocks and is present in the composition in an amount of from about 0.5% to about 10% by volume, based on a total volume of the matrix composition;

wherein the amphiphilic block copolymer, component (c), comprises at least one polyether block A and at least one polyether block B;

wherein the polyether block A is independently selected from a polybutylene oxide block, a polyhexylene oxide block, a polydodecylene oxide block, and a polyhexadecylene oxide block; and

wherein the polyether block B is independently selected from a polyethylene oxide block, a polypropylene oxide block, and a poly(ethylene oxide-co-propylene oxide) block;

wherein a weight ratio of the polyether block A to the polyether block B in the amphiphilic block copolymer, component (c), is from about 10:1 to about 1:10;

wherein the epoxy resin, component (a), is present in an amount of from about 30% to about 95% by volume, based on the total volume of the matrix composition;

wherein the reactive diluent, component (b), is present in an amount of from about 5% to about 25% by volume, based on the total volume of the matrix composition; and

wherein the amphiphilic block copolymer, component (c), is present an amount of from about 1% by volume to about 5% by volume, based on the total volume of the matrix composition.

2. The windmill blade of claim 1 , wherein the matrix composition provides a fracture toughness of an article made therefrom which is higher than a fracture toughness of an article made from a comparative composition which has the same initial viscosity as the matrix composition and comprises only the epoxy resin, component (a) and the reactive diluent component (b).

3. The windmill blade of claim 2 , wherein the fracture toughness of the article made from the matrix composition is at least about 150% of the fracture toughness of the article made from the comparative composition.

4. The windmill blade of claim 3 , wherein the viscosity of the matrix composition increases at a rate which is about the same or lower than a rate at which the viscosity of the comparative composition increases under the same conditions.

5. The windmill blade of claim 1 , wherein the amphiphilic block copolymer, component (c), comprises at least one block A of poly(butylene oxide) and at least one block B of poly(ethylene oxide); or wherein the amphiphilic block copolymer, component (c), comprises one or both of a poly(ethylene oxide)-b-poly(butylene oxide) block copolymer and a poly(ethylene oxide)-b-poly(butylene oxide)-b-poly(ethylene oxide) block copolymer.

6. The windmill blade of claim 1 , wherein the amphiphilic block copolymer, component (c), comprises a poly(ethylene oxide)-poly(propylene oxide) block copolymer comprising from about 5% to about 30% by weight of one or more poly(ethylene oxide) blocks and from about 70% to about 95% by weight of one or more poly(propylene oxide) blocks, based on a total weight of the block copolymer.

7. The windmill blade of claim 6 , wherein the block copolymer comprises not more than about 20% by weight of the one or more poly(ethylene oxide) blocks.

8. The windmill blade of claim 1 , wherein the at least one amphiphilic block copolymer has a number average molecular weight (Mn) of from about 1,000 to about 30,000.

9. The windmill blade of claim 1 , wherein the epoxy resin, component (a), is selected from polyglycidyl ethers of polyhydric alcohols, polyglycidyl ethers of polyhydric phenols, polyglycidyl amines, polyglycidyl amides, polyglycidyl imides, polyglycidyl hydantoins, polyglycidyl thioethers, epoxidized fatty acids or drying oils, epoxidized polyolefins, epoxidized di-unsaturated acid esters, and epoxidized unsaturated polyesters.

10. The windmill blade of claim 9 , wherein the epoxy resin, component (a), comprises at least one diglycidyl ether of a bisphenol compound; and wherein (a) has an epoxide equivalent weight of from about 100 to about 3,000.

11. The windmill blade of claim 1 , wherein the epoxy resin, component (a), has a viscosity at 25° C. of at least about 1,000 cps; wherein the reactive diluent, component (b), has a viscosity at 25° C. which is not higher than about 100 cps; wherein the matrix composition has a viscosity at 25° C. which is not higher than about 1,000 cps.

12. The windmill blade of claim 1 , wherein the matrix composition further comprises one or more curing agents.

13. The windmill blade of claim 1 , wherein the reinforcing fibers comprise one or more of carbon fibers, graphite fibers, boron fibers, quartz fibers, aluminum oxide fibers, glass fibers, silicon carbide fibers, and aramid fibers; and wherein the reinforcing fibers are present in an amount of from about 5% to about 80% by weight, based on a total weight of reinforcing fibers plus matrix.

14. The windmill blade of claim 1 , wherein the windmill blade is at least about 20 meters in length.