Last winter, MIT researchers discovered that a phenol-formaldehyde polymer transformed into a glassy carbon material in a process similar to baking reaches its best combination of high strength and low density at 1,000 degrees Celsius (1,832 degrees Fahrenheit). Now they have determined that, they can achieve a similar glassy transformation, but at a more industrially-accessible temperature of 800 C by adding a small fraction of carbon nanotubes to this material.
As the starting polymeric hydrocarbon, known as a phenol-formaldehyde polymeric resin, is heated from 600 C, the size of its crystallites grows until it reaches a plateau at 1,000 C. Postdoc Itai Y. Stein says scientific literature shows that this plateau holds until well above 2,000 C. The addition of 1 percent by volume of aligned carbon nanotubes to the starting material allows it to reach the plateau crystallite size at a termperature 200 C lower.
“What we’re showing is that by adding carbon nanotubes, we reach this plateau region earlier,” Stein says. The findings were reported Aug. 22 in the Journal of Materials Science online. The co-authors were Stein, former Materials Processing Center-Center for Materials Science and Engineering (MPC-CMSE) Summer Scholars Ashley L. Kaiser (2016) and Alexander J. Constable (2015), postdoc Luiz Acauan, and the senior author, professor of aeronautics and astronautics Brian L. Wardle. Kaiser is now a graduate student in Wardle’s lab.