Thermal and structural characterization of nanofibers of poly(vinyl alcohol) produced by electrospinning

Abstract

Poly(vinyl alcohol) (PVOH) was obtained from the alkaline hydrolysis of poly(vinyl acetate) (PVAc). Nonwoven membranes (mats) of PVOH nanofibers were produced by electrospinning of solutions of PVOH in water with and without aluminum chloride. The concentration of the PVOH/water solution was 12.4% w/v. The morphology of the mats was analyzed by scanning electron microscopy (SEM). The thermal properties and the degree of crystallinity of the nanofibers were measured by differential scanning calorimetry (DSC); the crystal structure of the mats was evaluated by wide-angle X-ray diffraction. The best nanofibers were obtained by electrospinning the PVOH/ water solution with aluminum chloride (45% w/v) in which an electrical field of 3.0 kV/cm was applied. It was observed that the addition of the aluminum chloride and the increase in the applied electrical field decreased the number-average nanofibers diameters. The mats without aluminum chloride had higher melting temperatures and higher degrees of crystallinity than the mats with the salt. The crystal structure of the mats was found to be monoclinic; however, the mats were neither highly oriented nor have a high degree of crystallinity.

Preparação e Caracterização de Nanofibras de Nanocompósitos de Poliamida 6,6 e Argila Montmorilonita

“…Em 2007 foram depositadas duas patentes em parceria com a empresa Rhodia ® Poliamida e Especialidades [13,21] . Este mesmo grupo tem processado nanofibras de vários outros sistemas poliméricos como os biopolímeros poli(álcool vinílico) [22,23] , poli(ácido lático) [24,25] , poli(ε-caprolactona) (PCL) [26] , poli(hidroxibutirato) [27] poli(butileno adipato-co-tereftalato) (PBAT) [28] , e nanocompósitos de poliamida 6/montmorilonita [14] , PCL/montmorilonita [29] e de PBAT/montmorilonita [28] .…”

Eletrofiação de Polímeros em Solução: parte I: fundamentação Teórica

“…Estes parâmetros estão relacionados com as propriedades físico-químicas dos polímeros, dos solventes e com as interações do tipo polímero-solvente [47] . A concentração do polímero e, consequentemente, a viscoelasticidade da solução, é um parâmetro de fundamental importância na eletrofiação [48,49] . Para se obter nanofibras uniformes sem contas é necessário que se tenha um grau de emaranhamento de cadeias na solução polimérica, a qual corresponde a um valor de concentração (viscoelasticidade) mínimo [50] .…”

Nanocomposites of polyamide 6/residual monomer with organic-modified montmorillonite and their nanofibers produced by electrospinning

“…The setup the electrospinning apparatus was reported in our previous work 13 . During the solutions electrospinning, two different electrical fields were used: 2.5 and 5.0 kV.cm -1 .…”