Effects of MWNT nanofillers on structures and properties of PVA electrospun nanofibres (original) (raw)
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Nanotechnology, 2008
Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both the pure PVA and SWNT/PVA composite nanofibers were subjected to the following post-electrospinning treatments: (i) soaking in methanol to increase the PVA crystallinity, and (ii) cross-linking with glutaric dialdehyde to control the PVA morphology. Effects of the PVA morphology on the tensile properties of the resultant electrospun nanofibers were examined. Dynamic mechanical thermal analyses of both pure PVA and SWNT/PVA composite electrospun nanofibers indicated that SWNT-polymer interaction facilitated the formation of crystalline domains, which can be further enhanced by soaking the nanofiber in methanol and/or cross-linking the polymer with glutaric dialdehyde.
Electrospinning was used to elaborate poly(vinyl alcohol) (PVA) nanofibers in the presence of embedded multiwall carbon nanotubes (MWCNTs) in surfactant and polymer. MWCNTs were dispersed in aqueous solution using both sodium dodecyl sulfate (SDS) as surfactant and Poly(vinyl pyrrolidone) (PVP). Changing the surfactant and polymer concentration reveals that the maximum dispersion achievable is corresponding to the mass ratios MWCNTs : SDS—1 : 5 and MWCNTs : SDS : PVP—1 : 5 : 0.6 in the presence of the PVP. After the optimization of the dispersion process, the SEM image of the PVA/PVP/SDS/MWCNTs electrospun fibers presents high stability of the fibers with diameter around 224 nm. Infrared spectroscopy and thermal gravimetric analysis elucidate the type of interaction between the PVA and the coated carbon nanotube.The presence of PVP wrapped carbon nanotubes reduced slightly the onset of the degradation temperature of the electrospun nanofibers.
Mechanical behaviour of MWCNTs reinforced electrospun nanofibres
Journal of Macromolecular Science, Part A, 2019
The nanoscale dimension of electrospun polymeric nanofibres produced by electrospinning are highly captivating, yet facing limitation of resisting external forces due to the weak tensile properties. Carbon nanotubes providing tremendous toughness due to extraordinary strong sp 2 bonding network of carbon atoms in honeycomb lattice structure, augmented the physical resistant strength and is easily recover to its original state after load is removed. This study reports the performance of multi-walled carbon nanotubes (MWCNTs) as filler in the electrospinning of poly (L-lactide)-co-e-caprolactone) (PLCL) composite nanofibres. Voltage of 10 kV is applied to the spinning solution mixture of 11 wt% (w/v) PLCL and MWCNTs, yielded nanofibres having diameters less than 400 nm. Results obtained showed the formation of composite nanofibres with tailored tensile behavior by modifying the content of MWCNTs. The addition of MWCNTs improved the tensile properties of resultant composite nanofibres, signified by tensile strength of 5.82 to 15.95 MPa, which were obtained using 0.1 to 1.0 wt% of MWCNTs. The structural integrity of nanofibres mats were retained in phosphate buffer saline (PBS) medium. Scanning Electron Microscopy (SEM) micrographs revealed the minimal of fiber deformation over 30 days of incubation and are closely identical to the initial diameter of as-spun fiber.
Effect of Molecular Weight on the Morphology of Electrospun Poly ( Vinyl Alcohol ) Nanofibers
2014
Morphological characteristics of electrospun PVA nanofibers were investigated in terms of polymer molecular weight was reported in this paper. The change in the morphology depending on the polymer concentration of electrospinning solution and the applied voltage were addressed. The fiber diameter increased with the increase in the molecular weight and polymer concentration and applied voltage and the average nanofiber diameter variation was found to be between 175.83 and 735.69 nm.
Using A Range of PVB Spinning Solution to Acquire Diverse Morphology for Electrospun Nanofibres
Morphological changes in Polyvinyl Butyral (PVB) electrospun nanofibres can be acquired by preparation of PVB spinning solution in different solvents. Accordingly, three solvents, including ethyl alcohol, n-butanol and isopropanol, with diverse physical properties (e.g. boiling point, density, dipole moment and dielectric constant) were used to prepare PolyVinyl Butyral (PVB) spinning solution. The PVB polymer was used in two ranges of molecular weight. Scanning Electron Microscopy (SEM) was employed to determine the morphological aspects. Results demonstrated a very high increase in the nanofibre diameter, with decreasing dipole moment and increasing boiling point and density of solvents. The smallest nanofibre diameter and bead structure was revealed for the PVB solution prepared by n-butanol. With regard to morphological aspects, isopropnol was selected as the most suitable solvent for a range of PVB molecular weights
AIP Conference Proceedings, 2016
Four temperatures of heat treatment had been used (110 ºC, 135 ºC, 150 ºC, and 160 ºC) to give different effects on the morphology of PVA nanofibers. Heat treatment changed the crystallinity of PVA nanofibers which was indicated by the changes of XRD FWHM spectral peaks, and the crystallite size. The changes in the intensity of FTIR spectral transmittance were also observed which might be caused by the differences temperature of heat treatment. The larger crystallite size and the smaller XRD FWHM spectral values indicated greater crystallinity of PVA nanofibers that was expected to increase the stability and physical properties of PVA nanofibers.
The dispersion stability behavior of single walled carbon nanotube (SWCNT) has important effects on morphological and mechanical properties of SWCNT/polymer composite nanofibers. The effects of SWCNTs incorporation on the morphological and structural developments and the relation between this develo pments and mechanical properties of the polyacrylonitrile (PAN) nanofibers were demonstrated. The uniform, stable dispersion and well oriented SWCNT within the PAN matrix were achieved through using polyvinylpyrrolidone (PVP) as dispersing agent. Our data indicate that with increasing the amount of SWCNT (from 0 to 2 wt %), the average nanofiber diameter was increased from 163±19 nm to 307±34 nm. The analysis of the mechanical properties of the composite nanofibers displays that they exhibit an improvement in the tensile strength of ∼172% from 3.93±0.45 MPa to 10.74±1.03 MPa, and the elastic modulus was increased by ~885% from 61.39±15.58 GPa to 605.08±65.55 GPa, as compared to the pure electrospun nanofibers. The optimal SWCNT concentration for electrospun nanofibers with better morphological and mechanical properties is ~2 wt %.
On the electrospinning of poly(vinyl alcohol) nanofiber mats: A revisit
Journal of Applied Polymer Science, 2008
Electrospinning was used to fabricate mats of poly(vinyl alcohol) (PVA; M w 5 72,000 Da, degree of hydrolysis 97.5-99.5) nanofibers from PVA solutions in reverse osmotic water. The effects of solution concentration, applied electrical potential, sonication, and collection distance on morphological appearance and diameters of the as-spun fiber mats as well as those of the individual fibers were carefully investigated mainly by scanning electron microscopy. The effect of the distance from the center of the as-spun fiber mat on morphological appearance and diameters of the as-spun fibers was also investigated. The mechanical integrity of some as-spun PVA fiber mats was also investigated. At all concentrations and applied electrical potentials investigated, the average diameters of the as-spun PVA fibers ranged between 85 and 647 nm. The use of sonication to prepare a PVA solution caused the viscosity of the solution to decrease; hence, the observed decrease in the average diameters of the as-spun fibers and the average diameters of the asspun fibers were practically the same throughout the asspun fiber mat.
Theoretical and Applied Fracture Mechanics, 2018
The current work studies the electrospun poly (vinyl alcohol) (PVA) nanofibers and its nanocomposites including nanohydroxy apatite (nHAp) and nHAp/cellulose nanofibers (CNFs), emphasizing the impact of nanofillers on the toughness of nanofibers. PVA nanofibers were incorporated with 10 wt% of nHAp and then various amounts of CNF were added to subsequent PVA/nHAp fibrous nanocomposites. The morphology of nonwoven mats was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). While neat PVA nanofibers were smooth and uniform in thickness, the nanofiller loading resulted in thinner fibers with less uniformity. Furthermore, the thermal properties of the nonwoven network of fibers were characterized employing thermogravimetric analysis (TGA). Although the maximum loss mass temperature of PVA was partially reduced upon addition of nanofillers, the onset of decomposition was not altered. The mechanical characterizations were performed using static tensile and dynamic mechanical analysis (DMA). Compared to neat PVA mats, the tensile test of nanocomposites mats demonstrated the significant increase in Young's modulus; however, strain at break was dramatically reduced. In addition, the fracture work was assessed from the area under the stress-strain curve, which showed brittleness of fibrous nanocomposites due to the nanofiller incorporation. Field emission SEM (FE-SEM) was employed to scan the fracture surface of stretched fibers. The increase in modulus of electrospun mats was also shown by DMA in frequency mode. In parallel, both tensile test and DMA confirmed the change in fracture of PVA fibers from a tough to brittle mode, due to the nanofiller addition.
Optimising the electrospinning process conditions to produce polyvinyl alcohol nanofibres
International Journal of Nanotechnology, 2009
Polyvinyl alcohol (PVA) is a semi-crystalline, hydrophilic polymer with reasonable physical and mechanical properties which has broadly practical applications. Ultra fine PVA fibres which have potential applications in filtration and biomedical engineering could be produced by electrospinning. In this work the process conditions to produce PVA nanofibres were optimised and the effects of various variables such as electric voltage, tip to target distance, flow rate and solution parameters on the morphology of nanofibres were investigated. The mechanical properties of fibre mats such as Young's modulus and tensile strength were also evaluated. The results showed that the fibre diameter and morphology were significantly affected by these parameters. The fibre diameter was in the range of 300-500 nm which is decreased with increasing the tip to target distance and electric voltage. It is also reduced with lessening flow rate and solution concentration.