HAIFA, Israel, Feb. 1 (UPI) -- Israeli scientists have determined tiny polymer nanofibers become much stronger when their diameters shrink below a certain size.
When Technion-Israel Institute of Technology researchers Eyal Zussman and Oleg Gendelman measured the mechanical properties of nylon nanofibers, they found the critical diameter -- the diameter at which the nylon nanofiber abruptly becomes stiffer -- to be approximately 500 nanometers, or 100 times thinner than a human hair.
Zussman said each polymer nanofiber is made up of countless large, complex molecules called macromolecules that try to align themselves when the fiber is forming. But since they are so long and tangled, it is impossible for them to align uniformly throughout the entire nanofiber.
As a result, said Zussman, the nanofiber is a patchwork of differently oriented macromolecule regions. The researchers calculated the size of those regions to be roughly the same as the critical diameter of the nanofiber.
"But as the diameter of the fiber shrinks, these oriented regions become constrained and the macromolecules are unable to easily move relative to one another. So they become stuck against each other ... and the resulting nanofiber is much stiffer."
The study appears in the January issue of Nature Nanotechnology.
