1/28/2011
Investigation of post-spinning stretching process on morphological, structural, and mechanical properties of electrospun polyacrylonitrile copolymer nanofibers  
(519-528) Polymer 52 #2 (2011)
Lai et al formed electrospun polyacrylonitrile (PAN) copolymer nanofibers with diameters of 0.3 μm were prepared as highly aligned bundles. The as-electrospun nanofiber bundles were then stretched in steam at 100 °C into 2, 3, and 4 times of the original lengths.  The study revealed that: (1) the macromolecules in as-electrospun nanofibers were loosely oriented along fiber axes; although such an orientation was not high, a small extent of stretching could effectively improve the orientation and increase the crystallinity; (2) most of macromolecules in the crystalline phase of as-electrospun and stretched nanofibers possessed the zig-zag conformation instead of the helical conformation; and (3) the post-spinning stretching process could substantially improve mechanical properties of the nanofiber bundles. (RDC 1/27/2011)

10/29/2010
Formation and characterization of core-sheath nanofibers through electrospinning and surface-initiated polymerization 
(4368-4374) Polymer 51 #19 (2010)
Ji et al of North Carolina State University fabricated core-sheath nanofibers, composed of polyacrylonitrile (PAN) core and polypyrrole (PPy) sheath with clear boundary between them by electrospinning PAN/FeCl3·6H2O bicomponent nanofibers and the subsequent surface-initiated polymerization in a pyrrole-containing solution.  By adjusting the concentration of FeCl3·6H2O, the surface morphology of PPy sheath changed from isolated agglomerates or clusters to relatively uniform thin-film structure.  The PPy sheath played a role of inhibitor and retarded the complex chemical reactions of PAN during the carbonization process.  (RDC 12/19/2010)