橡树岭实验室将聚乙烯转化为碳纤维

Common material such as polyethylene（聚乙烯） used in plastic bags could be turned into something far more valuable through a process being developed at the Department of Energy's Oak Ridge¹ National Laboratory. In a paper published in Advanced Materials, a team led by Amit Naskar of the Materials Science and Technology Division outlined a method that allows not only for production of carbon fiber² but also the ability to tailor the final product to specific applications.

"Our results represent what we believe will one day provide industry with a flexible technique for producing technologically³ innovative⁴ fibers⁵ in myriad⁶（无数的） configurations⁷ such as fiber bundle or non-woven mat assemblies," Naskar said.

Using a combination of multi-component fiber spinning and their sulfonation（磺化） technique, Naskar and colleagues demonstrated that they can make polyethylene-base fibers with a customized surface contour（轮廓，等高线） and manipulate filament⁸ diameter down to the submicron scale. The patent-pending process also allows them to tune⁹ the porosity¹⁰（有孔性） , making the material potentially useful for filtration, catalysis and electrochemical energy harvesting.

Naskar noted¹¹ that the sulfonation process allows for great flexibility¹² as the carbon fibers exhibit properties that are dictated¹³ by processing conditions. For this project, the researchers produced carbon fibers with unique cross-sectional geometry, from hollow circular to gear-shaped by using a multi-component melt extrusion-based fiber spinning method.

The possibilities are virtually endless, according to Naskar, who described the process.

"We dip the fiber bundle into an acid containing a chemical bath where it reacts and forms a black fiber that no longer will melt," Naskar said. "It is this sulfonation reaction that transforms the plastic fiber into an infusible（不熔化的） form.

"At this stage, the plastic molecules¹⁴ bond, and with further heating cannot melt or flow. At very high temperatures, this fiber retains mostly carbon and all other elements volatize off in different gas or compound forms."

The researchers also noted that their discovery represents a success for DOE, which seeks advances in lightweight materials that can, among other things, help the U.S. auto¹⁵ industry design cars able to achieve more miles per gallon with no compromise in safety or comfort. And the raw material, which could come from grocery store plastic bags, carpet backing scraps¹⁶ and salvage¹⁷（打捞） , is abundant and inexpensive.