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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Electrospinning and Characterization of Polyamide 66 Nanofibers With Different Molecular Weights

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Guerrini, Lilia Muller [1] ; Branciforti, Marcia Cristina [1] ; Canova, Thomas [2] ; Suman Bretas, Rosario Elida [1]
Total Authors: 4
[1] Univ Fed Sao Carlos, Dept Mat Engn, BR-13565905 Sao Carlos, SP - Brazil
[2] Rhodia Text, Santo Andre, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 12, n. 2, p. 181-190, abr./jun. 2009.
Field of knowledge: Engineering - Materials and Metallurgical Engineering
Web of Science Citations: 36

Polyamide 66 (PA66) nanofibers of different molecular weights were obtained by electrospinning of formic acid solutions. An ionic salt, NaCl, was also added to the solutions to increase the conductivity. PA66 concentrations between 15-17 wt.(%)/v and electrical fields between 2.0 and 2.5 kV/cm were the best conditions to produce the smallest nanofibers; however, the addition of NaCl increased the fibers average diameters.The characterization of the fibers was done by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), wide angle X rays diffraction (WAXD) and Fourier Transformed Infrared (FTIR). As the molecular weight decreased, the nanofibers average diameters also decreased; however, critical number average and weight average molecular weights were necessary for electrospinning. As the amounts of carboxyl terminal groups (CTG) increased, the nanofibers average diameters decreased; however, above CTG's critical values of 8.7 x 10-5 mol.g-1 no electrospinning was possible. The addition of ionic salt increased the electrical conductivity of the solutions and increased the nanofibers' average diameters. By DSC, residual solvent in all the electrospun mats was found; two melting endotherms, one between 248 and 258 ºC and the other one between 258 and 267 ºC, depending on the sample were also observed. These endotherms were attributed to the melting, re-crystallization and re-melting of the PA66 ALPHA-phase. The nanofibers had low % of crystallinity compared to a textile fiber. By WAXS and FTIR, confirmation of the presence of ALPHA-phase crystals, of small dimensions and highly imperfect and of a very small amount of BETA and GAMA-phases crystals in the nanofibers structure was obtained. (AU)

FAPESP's process: 06/61008-5 - Nanostructure polymeric systems: processing and properties
Grantee:Rosario Elida Suman Bretas
Support type: Research Projects - Thematic Grants