Spooling out Carbon Nanotube Ribbons for Stronger Composites
Researchers from North Carolina State University have developed new techniques for stretching carbon nanotubes (CNTs) and using them to create carbon composites that can be used as stronger, lighter materials in everything from airplanes to bicycles. In this clip, aligned CNTs are wound onto a rotating spool and sprayed with a polymer solution to bind the CNTs together. This creates a ribbon-like composite material that has a high percentage of CNTs by volume. The CNTs are stretched as they are being pulled onto the rotating spool, which straightens them. This process improves the tensile strength of the CNT composite 'ribbon' by approximately 90 percent (to an average of 3.5 gigapascals) and stiffness by more than 100 percent. By straightening the CNTs, the researchers were also able to almost triple the CNT composite's thermal conductivity, to 40 watts per meter per kelvin. Electrical conductivity was increased by 50 percent to 1,230 siemens per meter.