Effect of relative humidity on the morphology of electrospun polymer fibers

Abstract

The effect of relative humidity on the morphology of electrospun fibers of poly(vinyl alcohol), poly(methyl methacrylate), poly(vinyl chloride), polystyrene, and poly(lactic acid) dissolved in solvents such as toluene, N,N-dimethylformamide, 2,2,2-trifluoroethanol, and deionized water was studied by scanning electron microscopy to investigate the factors that may contribute to pore formation. Results showed that the presence of pores depends on factors such as the type of polymers used, the polymer–solvent combination, molecular weight, and the size of the electrospun structure. The final morphology developed implies a competition between the dynamics of phase separation and the rate of solvent evaporation. In addition, continuous solvent evaporation and constant stretching owing to the electric potential difference give rise to the final shape of porous electrospun fibers.Key words: electrospinning, relative humidity, porous fibers, polymers.

An alternative solvent system for the steady state electrospinning of polycaprolactone

“…This trend could be confirmed at other acetic acid concentrations and might be attributed to the different effect of the humidity in the polymer jet due to differences in accessibility depending on the position of the molecules in the jet. Although this hypothesis of increasing deviation with increasing humidity has escaped examination in literature, calculations on fibre diameters of electrospun polyethylene oxide and polylactic acid nanofibres found in literature show a similar trend [47,48].…”

“…RH is an often overlooked, though important parameter which is known to have an influence on the fibre morphology [46][47][48]. To study the effect of the RH the nonwovens with varying polymer concentration were also produced at 50 % RH.…”

Eletrofiação de polímeros em solução: parte II: aplicações e perspectivas

“…Recentemente Picciani et al [67] compararam o grau de cristalinidade de nanofibras de diferentes composições de blendas de PLA e PANI obtidas por eletrofiação com os respectivos filmes obtidos por casting. Seus resultados corroboram com a interpretação microscopia eletrônica de varredura (MEV), microscopia eletrônica de emissão de campo (MEV-EC), microscopia eletrônica de transmissão (MET) e Microscopia de Força Atômica (MFA) [81][82][83] . Dentre essas três técnicas, a microscopia eletrônica de varredura é a mais usada para verificar a morfologia e determinar a distribuição de diâmetros das fibras, por fornecer uma visão mais geral da amostra.…”

Steady state electrospinning of uniform polyethersulfone nanofibers using a non-heated solvent mixture

“…The process parameters that were varied during electrospinning are the flow rate (0-2 mL/h), the tip to collector distance (TCD) (6-18 cm) and the applied voltage (0-30 kV). To minimize the effect of the ambient conditions (Medeiros et al 2008;De Vrieze et al 2008), all experiments were performed in a fume hood at room temperature (22 ± 2°C) and at a relative humidity of 45 ± 5 RH %, monitored by a Vaisala humidity probe. The morphology of the electrospun structures was examined using an FEI QUANTA 200 F Scanning Electron Microscope (SEM).…”