|Mattoso, Luiz - EMBRAPA, BRAZIL|
|Ito, Edson - EMBRAPA, BRAZIL|
Submitted to: Polymer Engineering & Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 2, 2007
Publication Date: January 10, 2008
Citation: Medeiros, E.S., Mattoso, L.H., Ito, E.N., Gregorski, K.S., Robertson, G.H., Offeman, R.D., Wood, D.F., Orts, W.J. 2008. Electrospun nanofibers of poly (vinyl alcohol) reinforced with cellulose nanofibrils. Polymer Engineering & Science. 2(3):231-242. Interpretive Summary: Electrospinning has been the subject of a wide number of recent studies because it is a simple and versatile technique to produce micro- and nano-structured polymer materials that can be used as filtration membranes, drug release systems, wound dressings, engineered tissues, protective clothing, sensors, and composites. Cellulose is particularly attractive for electrospinning and for use in (nano) composites because of its availability (cellulose is the most abundant biopolymer in nature) and because of its remarkable properties - it can improve mechanical performance even at low fiber concentrations. In this study, electrospun nanofibers of poly (vinyl alcohol) (PVA) reinforced with ag-derived cellulose nanofibrils (CnF) were created via careful control of process parameters such as pH and ionic strength. This allows the production of fibers with "tunable) properties, with diameters ranging from tens of microns down to a few nanometers. Betermining the effects of process variables on fiber structure and end-use properties gives us a better understanding of electrospinning science, but, nanocomposites with specific desired properties.
Technical Abstract: In this work, nanofibers of poly (vinyl alcohol) (PVA) reinforced with cellulose nanofibrils (CnF) were produced by electrospinning. The effects of applied voltage, polymer concentration and injection rate, tip-to-collector distance (TCD), rotation speed of the collector, and relative humidity on morphology were investigated by scanning electron microscopy (SEM) and the reinforcing capability of cellulose nanofibrils was investigated by tensile tests. Thermogravimetry (TG), Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) analyses were also carried out in order to characterize the presence, orientation and reinforcing effect of the cellulose nanofibrils. SEM results showed that fiber structure is strongly affected by the electrospinning conditions. Thinner fibers are favored by decreasing viscosity, polymer injection rate, high rotation speed and high relative humidity, whereas increasing the applied voltage favors that formation of beaded fibers. The reinforced composites had as 2.4-fold increase in their mechanical properties by addition of only 6.6 wt.% of cellulose nanofibrils without major changes in elongation at break.