Mechanics of PAN nanofibers

Novel and scalable fabrication methods, such as electrospinning and pulsed laser deposition, provide low-cost polymeric nanofibers for structural applications. However, there is insufficient knowledge about the structural and mechanical behavior of polymeric nanostructures, which, in turn, limits their potential as enabling materials. The knowledge void in the systematic mechanical characterization of polymeric nanofibers is addressed in this chapter with focus on the room-temperature temporal and scale-dependent mechanical response of polyacry-lonitrile (PAN) nanofibers. Their molecular structure and deformation processes are intimately related to their fabrication conditions, and this chapter describes the first effort in literature to establish fabrication-structure-properties interrelations. The nanoscale experiments presented here demonstrate strong diameter dependence of the elastic modulus and tensile strength of PAN nanofibers for a variety of electro-spinning conditions, while for particular fabrication conditions, the applied strain rate is shown to result in non-monotonic mechanical behaviors and very unusual deformation profiles during cold drawing.