Shifting of the melting point for semi-crystalline polymer nanofibers
Department of Mechanical Engineering, Technion, Israel Institute of Technology - Haifa 32000, Israel
2 Department of Materials Science and Engineering, SUNY at Stony Brook - Stony Brook, NY 11794-2275, USA
Accepted: 27 January 2011
The depression of melting temperature as a function of the diameter of electrospun semi-crystalline polymer nanofibers is discussed. Due to fast solvent evaporation during nanofiber electrospinning, there occurs the fixation of topological structure of the polymer matrix corresponding to chain entanglement of the initial concentration of the semi-dilute solution. The resulting level of chain entanglement is lower than that in polymer bulk at equilibrium. This difference results in an addition to the entropy jump corresponding to the polymer's melting, and accounts for the observed shift in melting temperature in as-spun fibers. The proposed concept is found to be in good agreement with experimental results obtained for as-spun poly(ethylene-co-vinyl acetate) (PEVA) and low-density polyethylene (LDPE) fibers.
PACS: 61.46.-w – Structure of nanoscale materials / 65.80.-g – Thermal properties of small particles, nanocrystals, nanotubes, and other related systems / 82.60.Qr – Thermodynamics of nanoparticles
© EPLA, 2011