Ultra-Strong Fibres of CNTs
Formation of an ultra-strong fiber of CNTs and poly (vinyl-alcohol) (PVA)
Because of the fantastic tensile properties of carbon nanotubes, many attempts have been made in order to make macroscopic fibers out of nanotubes that can maintain those properties on a macroscopic scale. One method is to inject a suspension of nanotubes into a flowing stream of poly (vinylalcohol) (PVA). The fast flow of the solution aligns the nanotubes, while the PVA acts as an adhesive, sticking the nanotubes together to form a fibre. The fibers thus made are expected to have enormous tensile strengths, making them appropriate for many applications including bullet-proof vests, sails and strong fabrics. As nanotubes themselves are known to change length in response to an applied voltage, these fibers are also expected to electromechanically respond to applied voltages by expanding and contracting. This property makes them candidates as artificial muscles.
I was lucky to have some very brilliant undergraduate students work on this project under my supervision. We made a rotary stage for spinning the PVA solution using a stepper motor. An automated plunger setup was made to inject the nanotube suspension in the spinning solution at the extremely slow flow rates needed for this setup. The setup was interfacing with a computer using MatLab xPC Target. The resulting fibers have shown tensile strengths of 650 MPa so far, but we are still hoping to improve on that.