Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Fabrication of Alumina Borate Nanofibe r by Electros pinning Technique
Mehtap Ozdemir 1 *, Aslihan Suslu 1 , Umit Cöcen 1 and Erdal Celik 1
1 Department of Metallurgical and Materials Engineering, Dokuz Eylul University, 35160, Izmir, Turkey
Abstract-Alumina borate (Al 18 B 4 O 33 ) nanofibers have been successfully fabricated by electrospinning method using a solution that contains
poly (vinyl alcohol) (PVA) and Aluminium acetate stabilizied with boric acid. The effect of viscosity and temperature were investigated.
DTA/TG analyses were done to determine the heat treatment regime. Morphology of the fibers was investigated by SEM analyses and phase
structure of fibers was obtained using XRD and chemical bonding structure was determined by FTIR.
One-dimensional materials, such as nanowires,
nanorods, nanowhiskers and nanofibers, have stimulated
great interest due to their importance in basic scientific
research and potential technology applications. They are
expected to play an important role as both interconnects
and functional components in the fabrication of nanoscale
devices. Many unique properties have already been
proposed or demonstrated for this class of materials, such
as high elastic modulus and tensile strength, chemical
inertness, excellent resistance to oxidation/corrosion, low
thermal expansion coefficient, high thermal conductivity,
stability at high temperature and low-cost production [1-5].
Of these properties, aluminium borate is one of the most
common materials for a variety of applications such as
high temperature structure components, nonlinear optical
and tribological materials, electronic ceramics and
reinforced composites materials [2, 6].
Electrospinning is a most preferred technique to produce
fibers with a diameter of 20-1000 nm. The diameter of the
fibers depends on process parameters; including viscosity
of the solution, applied electric field, distance between the
collector and needle and feeding rate of the solution [7].
In this study, we attempt to form alumina borate
nanofibers and investigate the effect of viscosity during the
electrospinning process on nanofiber morphology and
spinability.
We first prepared PVA solutions at different
concentrations. Then aluminium acetate stabilized with
boric acid (CH 3 CO 2 Al(OH) 2 .1/3H 3 BO 3 ) added to PVA
solution and stirring was continued until transparent and
homogeneous solution was obtained. Viscosity of
solutions was determined by CVO 100 Digital Rheometer.
The alumina borate/PVA fibers were heat treated at 800-
1200 o C for 2 h in air. The prepared solution used in the
electrospinning was dried at 100 °C for 1 h and the
obtained powder subjected to thermogravimetric
differential thermal analysis (DTA/TG) to define the
reaction type of intermediate temperature products and to
use suitable process regime. The chemical bonding
structures of fibers before and after heat treatment were
determined by Fourier Transform Infrared Spectroscopy
(FTIR). The X-ray diffraction (XRD) measurements were
performed for crystal phase identification (Rigaku D/Max-
2200/
average fiber diameter of nanofibers was characterized by
scanning electron microscope (SEM).
Solution viscosity plays a major role for producing
uniform nanofiber. At low viscosity, it is common to find
beads along the fibers. When the viscosity increases, there
is a gradual change in the shape of the fibers until smooth
fibers are obtained [8]. For spinability viscosity must be
neither very dense nor dilute. Viscosity of the prepared
solutions at different concentrations are determined in the
range of 0.17- 2.34 Pa.s. After the heat treatment of
electrospun fibers at 800
o C and 1200 o C, crystalline
Al 4 B 2 O 9 and Al 18 B 4 O 33 fibers were obtained respectively.
As a result of high temperature, fiber diameters reduced
from 922 nm to 523 nm.
In conclusion, the electrospinning technique was used to
produce alumina borate/PVA composite nanofibers. The
effect of viscosity on spinability and the morphology of
alumina borate/PVA nanofibers were investigated. After
heat treatment at 1200
o C, alumina borate (Al 18 B 4 O 33 )
fibers were produced. It has been found that viscosity of
the prepared solution affects the fiber morphology.
Increasing the viscosity as a result of increasing solution
concentration thicker fibers are obtained and furthermore
spinability of solution become more difficult because
dense solution leads to clogging of needle tip.
This work was supported by BOREN (National Boron
Research Institute) and TUBITAK (Scientific and
Technical Research Council of Turkey) project number
105M363. Also, authors M.O and A.S acknowledge the
support from TUBITAK, in the framework of the National
Scholarship Programmes for PhD Students.
*Corresponding author:
0Tmehtap.ozdemir@ogr.deu.edu.tr
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