Engineers at the Korea Institute of Science and Technology (KIST) have developed a flame-retardant carbon-fiber-reinforced composite material that dissolves into water — great for recycling, according to a recent study published in the journal Composites Part B: Engineering.
Carbon fiber reinforced plastic a boon to recycling
The team — led by Dr. Yong chae Jung — used tannic acid, a type of polyphenol usually synthesized from plants, to engineer a new material with carbon-fiber-reinforced plastic (CFRP).
"We have created a composite material with an expanded range of application that is a dramatic improvement over conventional carbon-fiber-reinforced plastic in terms of flame-retardancy, mechanical rigidity, and recyclability. These improved traits are significant in that they determine the range of application of said composite material," said Jung.
CFRP is roughly four times lighter than steel, yet 10 times stronger. Today it's widely used in the aerospace, sports equipment industries, and elsewhere.
CFRP must be flame-retardant, since it's used near or around processes that are susceptible to fire, like (for example) construction material. To ensure CFRP is safe around fires, it's sometimes synthesized with additives.
Carbon fiber bests halogen as flame-retardant
In the past, a halogen flame-retardant was used for this purpose. But the use of halogen in CFRP has since been banned worldwide because it generates toxic substances when put through a recycling process.
This is why KIST had to conceive of a non-toxic and safe material to create CFRP. Enter tannic acid, which bonds strongly with carbon fiber and turns into charcoal when burned.
The team then decided to produce epoxy resin from tannic acid and mix it into the carbon fiber. The result was a CFRP that's both strong and flame-retardant.
Additionally, the team also discovered that it was better and safer to dissolve the material in water — rather than incinerating the CFRP — to recycle it. They found that over 99% of the CFRP could be recovered and that the tannic acid when dissolved produced a substance called carbon dots which can be used as an electronic material.
Jung now has further plans for his new material: "We will be reviewing the structure of this composite material to achieve even further improved properties and to further expand the range of its application," said Jung.
As global industries are forced to rethink how they dispose of potentially-hazardous materials amid the advance of the global climate crisis, it's up to scientists to develop new innovative materials to help slow and eventually reverse the extent of environmental damage. But ultimately, the industries themselves must elect to use them.