Researchers at the U.S. Department of Energy’s Oak Ridge National Laboratory (ORNL) have developed an innovative method using carbon nanofibers to dramatically enhance bonding in carbon fiber and other fiber-reinforced polymer composites. The advancement, detailed in Advanced Functional Materials, could lead to stronger, lighter, and more cost-effective materials for transportation, aerospace, energy, and national security applications. 

Led by researcher Sumit Gupta, the ORNL team created a hybrid bonding approach using electrospun carbon nanofibers to improve both chemical and mechanical adhesion between the carbon fibers and the surrounding polymer matrix. This dual-bonding technique achieved a 50% increase in tensile strength and nearly doubled the composite’s toughness. 

“The challenge of improving adhesion between carbon fibers and the polymer matrix has long limited the full potential of these materials,” said Sumit Gupta. “Our approach creates nanoscale bridges between materials, significantly boosting performance.” 

Using electrospinning, polyacrylonitrile, a carbon fiber precursor, is drawn into nanofibers using a high-voltage electric field. These fibers, roughly 200 nanometers in width, are deposited onto carbon fiber fabric on a rotating drum. By fine-tuning the electrospinning process, researchers achieved precise control over bonding characteristics and fiber orientation.

The team used ORNL’s advanced imaging and characterization tools at the Center for Nanophase Materials Sciences, along with computational modeling on the Frontier supercomputer, to deeply understand the physical mechanisms behind the performance gains. 

“The multi-disciplinary support across ORNL was crucial,” said researcher Chris Bowland. “We’re now refining the technique for broader industrial use and exploring applications beyond carbon composites.” 

By improving adhesion, the technique could reduce material use and cost, making shorter, previously discarded carbon fibers viable. This has implications for expanding carbon fiber use into civil infrastructure, defense, and clean energy sectors. ORNL has applied for a patent and is seeking commercial partners to license the technology. 

Source: www.ornl.gov