Coaxial layered fiber spinning for wind turbine blade recycling

Abstract

Recycling wind turbine blades includes shredding, crushing, and milling the wind turbine blades to yield a multiplicity of particles including glass fiber and sieving the particles to yield a multiplicity of pellets including glass fibers. Manufacturing a composite coaxial fiber includes providing a first, second, and third polymer composition to yield a composite coaxial fiber precursor, processing the composite coaxial fiber precursor to yield a coagulated composite coaxial fiber precursor, drawing the coagulated composite coaxial fiber precursor, and heating the drawn coagulated composite coaxial fiber precursor to yield the composite coaxial fiber. The second polymer composition can include the recycled glass fibers. The resulting composite coaxial fiber includes an inner and outer layer including polyacrylonitrile and a middle layer between the inner layer and the outer layer. The middle layer includes polyacrylonitrile and a multiplicity of the recycled glass fibers.

What is claimed is: 
     
         1 . A composite coaxial fiber comprising:
 an inner layer comprising polyacrylonitrile;   an outer layer comprising polyacrylonitrile; and   a middle layer between the inner layer and the outer layer, wherein the middle layer comprises polyacrylonitrile and a multiplicity of glass fibers, wherein the multiplicity of glass fibers are recycled.   
     
     
         2 . The composite coaxial fiber of  claim 1 , wherein the multiplicity of glass fibers are present in an amount of 0.1 wt % to 200 wt % of the polyacrylonitrile in the middle layer. 
     
     
         3 . The composite coaxial fiber of  claim 1 , wherein a diameter of the composite coaxial fiber is in a range of about 50 μm to about 250 μm. 
     
     
         4 . The composite coaxial fiber of  claim 1 , wherein the middle layer has a thickness corresponding to the thickness of a single glass fiber of the multiplicity of glass fibers. 
     
     
         5 . The composite coaxial fiber of  claim 1 , wherein the multiplicity of glass fibers are aligned along a longitudinal axis of the composite coaxial fiber. 
     
     
         6 . The composite coaxial fiber of  claim 1 , wherein a draw ratio of the composite coaxial fiber is in a range from about 15 to about 65. 
     
     
         7 . A method manufacturing a composite coaxial fiber, the method comprising:
 providing a first polymer composition, a second polymer composition, and a third polymer composition to a spinneret to yield a composite coaxial fiber precursor, wherein the first, second, and third polymer compositions comprise polyacrylonitrile, the second polymer composition further comprises recycled glass fibers, and a layered precursor comprises coaxial layers of the first, second, and third polymer compositions, wherein a middle layer of the composite coaxial fiber precursor comprises the second polymer composition;   passing the composite coaxial fiber precursor through an air gap and into a coagulation bath to yield a coagulated composite coaxial fiber precursor;   drawing the coagulated composite coaxial fiber precursor through a heated liquid to align the recycled glass fibers in a middle layer of the coagulated composite coaxial fiber precursor, thereby yielding a drawn coagulated composite coaxial fiber precursor; and   heating the drawn coagulated composite coaxial fiber precursor to yield the composite coaxial fiber, wherein an inner layer, the middle layer, and an outer layer of the composite coaxial fiber comprises polyacrylonitrile, and the middle layer further comprises the aligned recycled glass fibers.   
     
     
         8 . The method of  claim 7 , wherein the first, second, and third polymer compositions comprise about 5 wt % to about 15 wt % polyacrylonitrile in a solvent. 
     
     
         9 . The method of  claim 8 , wherein the solvent comprises dimethylformamide. 
     
     
         10 . The method of  claim 8 , wherein the second polymer composition comprises about 0.1 wt % to about 200 wt % of the recycled glass fibers with respect to the weight of the polyacrylonitrile. 
     
     
         11 . The method of  claim 7 , wherein a flow rate of passing the composite coaxial fiber precursor through an airgap and into a coagulation bath is in a range of about 1 ml/min to about 3 ml/min. 
     
     
         12 . The method of  claim 7 , wherein a length of the air gap is about 1 cm to about 3 cm. 
     
     
         13 . The method of  claim 7 , wherein the coagulation bath comprises methanol. 
     
     
         14 . The method of  claim 7 , wherein the heated liquid comprises a water bath, an oil bath, or both. 
     
     
         15 . The method of  claim 14 , wherein an oil in the oil bath comprises a silicone oil. 
     
     
         16 . The method of  claim 14 , wherein a temperature of the water bath is in a range of about 80° C. to about 90° C. and a temperature of the oil bath is in a range of about 120° C. to about 150° C. 
     
     
         17 . The method of  claim 7 , wherein a draw ratio of the coagulated composite coaxial fiber precursor is in a range of about 15 to about 65. 
     
     
         18 . The method of  claim 7 , wherein heating the drawn coagulated composite coaxial fiber precursor comprises heating the drawn coagulated composite coaxial fiber precursor to a temperature in a range of about 250° C. to about 350° C. 
     
     
         19 . The method of  claim 18 , wherein the heating comprises heating at different rates for 1.5 hours and later cooling to room temperature at a rate of 1° C. per minute. 
     
     
         20 . The method of  claim 7 , wherein a diameter of the composite coaxial fiber is in a range of about 50 μm to about 250 μm. 
     
     
         21 . A method of recycling wind turbine blades, the method comprising:
 shredding, crushing, and milling the wind turbine blades to yield a multiplicity of particles comprising glass fiber; and   sieving the particles to yield a multiplicity of pellets comprising glass fiber.