Stress micro mechanical test cell, device, system and methods

Abstract

The present disclosure provides a stress micro mechanical system for measuring stress and strain in micro- and nano-fibers, tubes, and wires as well as for measuring the interface adhesion force and stress in nanofibers and nanotubes embedded in a polymer matrix. Also described are nanofibers comprising a cascade of surface ripples or periodic necks. Such surface features may be formed during cold drawing of electrospun nanofibers.

1 - 9 . (canceled) 
     
     
         10 . A nanostructure comprising:
 a nanofiber comprising a cascade of surface ripples.   
     
     
         11 . The nanostructure of  claim 10 , wherein the surface ripples comprise a periodicity. 
     
     
         12 . The nanostructure of  claim 11 , wherein an average spacing between the surface ripples is 50 nm. 
     
     
         13 . The nanostructure of  claim 10 , wherein the surface ripples comprise a depth of 20-40 nm. 
     
     
         14 . The nanostructure of  claim 10 , wherein the cascade of surface ripples extends along a length of the nanofiber. 
     
     
         15 . The nanostructure of  claim 10 , wherein the nanofiber comprises an outer surface over a fiber core, the outer surface comprising the surface ripples. 
     
     
         16 . The nanostructure of  claim 15 , wherein the outer surface is more brittle than the fiber core. 
     
     
         17 . The nanostructure of  claim 10 , wherein the nanofiber comprises a polymer. 
     
     
         18 . The nanostructure of  claim 17 , wherein the polymer comprises polyacrylonitrile. 
     
     
         19 . The nanostructure of  claim 10 , wherein the nanofiber has a diameter of from 300 nm to 600 nm. 
     
     
         20 . The nanostructure of  claim 10 , wherein the nanofiber has a length of 10-100 microns. 
     
     
         21 . The nanostructure of  claim 10 , wherein the nanofiber comprises an ultimate strain at fiber failure of 60-130%. 
     
     
         22 . The nanostructure of  claim 10 , wherein the nanofiber comprises a strength in the range of 30-130 MPa. 
     
     
         23 . The nanostructure of  claim 10 , wherein the nanofiber comprises an elastic modulus of from 6.1 GPa to 9.3 GPa. 
     
     
         24 . The nanostructure of  claim 10 , wherein the nanofiber is fabricated by electrospinning. 
     
     
         25 . The nanostructure of  claim 10 , wherein the surface ripples are formed during axial drawing of the nanofiber.