Wind turbine blades are the largest single application of engineered composites in the world. These large composite structures are primarily made from fiberglass reinforced epoxy resins. Carbon fibers can provide superior mechanical performance than glass fibers, due to their lower densities and higher fatigue ratio, which extends the lifetime of the turbine blades. However, the high costs of conventional carbon fiber, which starts with expensive polyacrylonitrile (PAN) polymer precursor, have limited their widespread use in wind turbine blades. Therefore there is a huge potential to reduce the production cost of carbon fibers by replacing PAN with low-cost materials from natural sources.
Lignin is an aromatic biopolymer, which is readily derived from plants and wood and can be used as a precursor for the production of carbon fibers. The low cost of lignin has been projected to result in savings of 37 to 49% in the final production cost of carbon fiber. Replacing PAN by lignin for wind turbine blades has a triple pay-off: it uses renewable resources, it optimizes energy and materials costs for producing carbon fibers, and the fibers themselves will be used for wind turbines to produce renewable energy. However, lignin is a very brittle biopolymer that cannot be spun, stretched/aligned, and spooled into fibers without modification.
Our state-of-the-art polymer processing equipment includes a bench scale production unit consisting of a twin-screw micro-compounder, a monofilament spin unit, and a fiber stretching and conditioning unit.
In this project we are developing a robust process for manufacturing high quality, low cost carbon fibers from lignin‐based precursor. Our aim is to devise methods to improve the processability of lignin‐based precursor so that small diameter lignin fiber can be produced, spun, and stretched prior to pyrolysis into carbon fiber.
Mahendra Thunga, Gauri Ramasubramanian, Ted Angus, David Grewell, Michael Kessler