4M Carbon Fiber Corporation and Dralon GmbH have co-developed a low-cost, textile-grade PAN precursor capable of producing a large-diameter carbon fiber. In preliminary efforts with this precursor, 4M has achieved industrial grade carbon fiber properties and a residence time for the oxidation phase of conversion of only 52 minutes. This is considerably faster than conventional oxidation of commercial (smaller diameter) precursors. Work is continuing to further improve the properties and optimize the material and the process.
4M Carbon Fiber Director and CTOTruman Bonds: "The initial target sector is industrial standard modulus applications. More interest would come from applications where compression strength is a concern, such as wind turbine blades or specific automotive parts.” Image Courtest of 4M Carbon Fiber Corp.
Large diameter refers to the average effective diameter of 9.63 µm for each individual filament. The industry average is 6–7 µm. The tow size was 10,000 filaments for this round of development. The tow size can vary depending upon customer and application requirements. The initial target sector is industrial standard modulus applications. More interest would come from applications where compression strength is a concern, such as wind turbine blades or specific automotive parts.
Until now, large diameter carbon fibers have not been produced at scale, mainly due to challenges related to the oxidation stage. Using conventional oxidation technology, the larger filaments require exceedingly long residence times, and the additional energy and time requirements result in a product that is not economically viable. Additionally, large-diameter carbon fibers tend to yield subpar performance as a result of defects introduced during conventional oxidation. For these reasons, carbon fiber manufacturers currently do not offer a large-diameter commercial carbon fiber product.
The advantages of a large diameter carbon fiber are lower cost and better performance. A larger diameter filament introduces cost savings throughout the manufacturing process, from precursor production to carbon fiber conversion, most readily seen in increased mass throughput. Combine this savings with the low-cost precursor Dralon normally produces, and the total cost savings becomes significant.
Carbon fibers are known for their high tensile strength, but they are not particularly strong in compression, especially compared to glass fibers. However, larger diameter carbon fibers can have significantly higher compressive strength. Advances in this aspect could enable new applications as well as growth in existing markets, such as wind turbine blades.
4M continues to push boundaries and redefine what’s possible in carbon fiber production with its patented technology. The company is pursuing its mission of revolutionizing the carbon fiber industry, and continues to expand its global licensing strategy through partnerships.