Hybrid Multi-scale basalt fiber-epoxy composite laminate reinforced with electrospun polyurethane nano fibers containing carbon nanotubes.

Fibers and Polymers 2014, Vol.15, No.6, 1295-1302

DOI 10.1007/s12221-014-1295-4

Hybrid Multi-scale Basalt Fiber-epoxy Composite Laminate Reinforced with
Electrospun Polyurethane Nanofibers Containing Carbon Nanotubes
I. D. G. Ary Subagia1, Zhe Jiang2, Leonard D. Tijing3, Yonjig Kim4,5*, Cheol Sang Kim2,4,
Jae Kyoo Lim4,5, and Ho Kyong Shon3
1

2

Mechanical Engineering, Faculty of Udayana University, Denpasar, Bali, Indonesia
Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756, Korea
3
School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), P.O. Box 123,
Broadway, NSW 2007, Australia
4
Division of Mechanical Design Engineering, Chonbuk National University, Jeonju 561-756, Korea
5
Advanced Wind Power System Research Center, Chonbuk National University, Jeonju 561-756, Korea

(Received September 10, 2013; Revised December 12, 2013; Accepted January 4, 2014)
Abstract: In this study, we report the fabrication and evaluation of a hybrid multi-scale basalt fiber/epoxy composite laminate
reinforced with layers of electrospun carbon nanotube/polyurethane (CNT/PU) nanofibers. Electrospun polyurethane mats
containing 1, 3 and 5 wt% carbon nanotubes (CNTs) were interleaved between layers of basalt fibers laminated with epoxy
through vacuum-assisted resin transfer molding (VARTM) process. The strength and stiffness of composites for each
configuration were tested by tensile and flexural tests, and SEM analysis was conducted to observe the morphology of the
composites. The results showed increase in tensile strength (4-13 %) and tensile modulus (6-20 %), and also increase in
flexural strength (6.5-17.3 %) and stiffness of the hybrid composites with the increase of CNT content in PU nanofibers. The
use of surfactant to disperse CNTs in the electrospun PU reinforcement resulted to the highest increase in both tensile and
flexural properties, which is attributed to the homogeneous dispersion of CNTs in the PU nanofibers and the high surface area
of the nanofibers themselves. Here, the use of multi-scale reinforcement fillers with good and homogeneous dispersion for
epoxy-based laminates showed increased mechanical performance of the hybrid composite laminates.
Keywords: Basalt fiber, Mechanical properties, Electrospinning, Polyurethane, Carbon nanotubes

basalt fiber reinforcement alone is still inferior to carbon
fiber reinforced laminate [13]. To further enhance the properties
of a fiber-reinforced polymer, multiple reinforcement length
scales are being developed and studied by many research
groups [14-17]. The emergence of polymer nanocomposite
has become a main factor supporting the rise of quality and

structural performance capability of basalt fiber as a reinforcing
material for polymer [18,19]. Recently, interleaving of
nanofibrous layers in the FRP has gained interest, wherein
the nanofibers where fabricated by an electrospinning technique.
Electrospinning is an easy, versatile and scalable way of
producing ultrafine nanofibers by the application of a high
electric field [20-22]. The fiber is produced in a size range of
a few microns to nano scale. The advantages of using
electrospinning are its low cost for fabrication, high surfacearea-to-volume ratio, easy combination with different fibers
[23,24], flexibility in surface functionalities, and superior
stiffness and tensile strength [25].
A number of studies have reported on the positive effect of
nanofiber-reinforcement in FRP [26-30]. Chen et al. [26]
reported an increase in interlaminar shear strength and flexural
properties of carbon fiber/epoxy composites when electrospun
carbon nanofibers were incorporated. Kelkar et al. [31]
investigated the effect of nanoparticles and nanofiber addition
to the Mode I fracture of fiber glass reinforced polymeric
matrix composites. In another study, electrospun polyetherketone
cardo (PEK-C) nanofibers were added to toughen carbon/

Introduction
In recent years, fiber reinforced polymer (FRP) composite
has become extremely popular in engineering and technology
[1], and is applied in many fields for components in aircraft,
spacecraft, ships, automobiles, civil infrastructure, sporting
goods, consumer products [2,3], and even in biomedical
devices [4]. The rise in FRP popularity gained momentum
because of its good density, high specific stiffness and
specific strength, good fatigue endurance, excellent corrosion
resistance, outstanding thermal insulation, and low thermal
expansion [5]. In the continued effort to enhance the
properties of FRP composites, many research groups have
sought out different techniques such as modifying the production
method, surface modification of reinforcing fibers [6], and
incorporation of nanoparticles [7,8] and nanofibers [9].
However, more stringent environmental laws have driven
research to the use of natural fibers as reinforcements. In this
regard, basalt fiber has gained increasing interest as a
reinforcing filler to composites as an alternative to glass [10]

and carbon [11] fibers due to its many advantages in terms of
cost, physical, mechanical, and chemical properties, and
being environmentally-friendly [12]. Yet, basalt has still
lower overall mechanical and physical properties compared
to carbon fiber, thus the resulting composite laminate from
*Corresponding author: yonjig@jbnu.ac.kr
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Fibers and Polymers 2014, Vol.15, No.6

epoxy laminates [12]. The authors reported a considerable
enhancement of interlaminar fracture toughness of the
carbon/epoxy composites even at a low PEK-C nanofiber
weight loading of 0.4 %. However, based from the current
literature, most of the nanofiber reinforcement for FRP were
in the neat polymer nanofiber state, i.e., only nanofibers
were incorporated in the fiber-epoxy matrix, mostly carbon
fiber-based composites. The effect of addition of nanoparticles

inside the nanofiber as a further reinforcement strategy could
provide better resulting mechanical properties, and is ought
to be investigated. In this study, we incorporated electrospun
polyurethane (PU) nanofibers in a basalt fiber-epoxy laminate.
The PU nanofibers were incorporated with different concentrations of carbon nanotubes with and without surfactant.
Here, PU was chosen because it is one of the widely used
polymers due to its excellent mechanical and thermal properties,
good abrasion resistance and fatigue life, and also water
insolubility [32]. Many research studies have explored the
use of electrospun polyurethane nanofibers as a constituent
of composites material including the incorporation of
nanoparticles to impart functionality to the nanofibers [33,
34]. Among nanoparticle reinforcements, carbon nanotubes
(CNTs) stand out as nanofiller because of their high aspect
ratio, very low density, small size and excellent mechanical
and electrical properties [35].
To the authors’ best knowledge, no one has reported yet
the use of electrospun CNT/PU nanofibers as reinforcement
to basalt fiber-reinforced epoxy laminate. In this study, we
investigated the effect of the CNT concentration and the PU

nanofiber reinforcement on the tensile and flexural properties
of the composite laminate fabricated by VARTM. Tensile
and flexural testing (three point bending) were conducted to
investigate the effect of electrospun CNT/PU neat with
different weight fractions toward the mechanical properties
of composites. The fracture surface of composites were also

I. D. G. Ary Subagia et al.

studied by scanning electron microcope (SEM) to assess the
toughening mechanism due to the thin electrospun CNT/PU
nanofibers and the possible interaction between the basalt
fiber, epoxy matrix, and electrospun CNT/PU nanofibers.

Experimental
Materials
Plain woven basalt fibers (EcoB4 F210) supplied by SecoTech. (Korea), with a weight 210±10 g/m2 and thickness
0.19±0.20 mm were used as reinforcement of the composites
without surface modification. Epoxy resin (HTC-667C) was
used with specific gravity=1.16±0.02 and viscosity=1200±

500 cps which includes a modified aliphatic amine hardener
produced by Jet Korea Co. (Korea). High molecular weight
thermoplastic polyurethane (PU) was provided by Lubrizol
Advanced Materials, Inc. Methyl ethyl ketone (MEK), and
acetone and N,N-dimethylformamide (DMF) were purchased
from Junsei Chemical Co. Ltd., Japan and Showa Chemical
Co., Ltd., Japan, respectively. Triton X-100 was used as
surfactant and was bought from OCI Company. All reagents
were used without any further purification. Multi-walled
CNTs with an average diameter of 11 nm, length=10-30 µm,
and purity >95 % were used which were synthesized by
chemical vapor deposition (CVD) and were provided by
Nanosolutions, Inc. (Korea).
Electrospinning
To prepare the CNT/PU solutions, different CNT concentrations (i.e., 1, 3, and 5 wt%) based from the weight of PU
were added to 10 wt% PU in DMF/MEK (50/50, wt/wt%)
solution. Prior to mixing in PU solution, CNT in DMF/MEK
were bath sonicated (40 Hz, Mujigae, Korea) for 1 h. Another
solution containing 3 wt% CNT/DMF/MEK solution was
added with surfactant Triton-X in the ratio of 1:5 (CNT:

Figure 1. Schematic layout of the hybrid composite laminate fabrication process including the solution preparation, electrospinning of
nanofibers, and vacuum-assisted resin transfer molding.

Hybrid Multi-scale Basalt Fiber Composite Laminate
Table 1. Name convention and components of the present neat
BFRP and hybrid composite laminates
Specimen
BFRP
BPC-1
BPC-2
BPC-3
BPC-4

Configuration
BF/Epoxy (HTC-667C)
BF+1 wt% CNT/PU nanofibers
BF+3 wt% CNT/PU nanofibers
BF+5 wt% CNT/PU nanofibers
BF+(3 wt% CNT+surfactant)/PU nanofibers

Figure 2. Placement, design and dimension of specimens for (a)
tensile and (b) flexural tests.

Triton-X, wt/wt%), to study the effect of surfactant in the
dispersion of CNT and its subsequent effect to the mechanical
property enhancement of the composite.
Electrospinning was carried out in the set-up described in
a previous report [36]. A high voltage of 15 kV was applied
to the electrospinning solution inside a plastic syringe at a
feed rate of 1 ml/h. The distance of needle tip and a flat
aluminum collector covered with basalt fiber layer (size of
25×25 mm) was kept constant at 150 mm (see Figure 1). The
sealed chamber humidity was kept at 30 %. After electrospinning, the nanofibers attached on basalt fiber layers were
dried at 60 oC for 48 h in an oven to remove residual solvents.

Fibers and Polymers 2014, Vol.15, No.6

1297

Fabrication of Hybrid Composite Laminate by VARTM
Figure 1 shows the design and fabrication process of the
present hybrid composite laminates. In this study, twelve
plies of basalt fiber layer laminates with area of ~500 mm2
with or without two plies of CNT/PU electrospun nanofibrous
layer interleaved between them were prepared and fabricated
by a vacuum assisted resin transfer molding (VARTM)
process [37]. Table 1 shows the components, concentration,
and names of the different samples prepared in this study.
Before the lamination process, the neat PU or CNT/PU
nanofibers were directly electrospun to basalt fiber layers
and were arranged accordingly in the composite laminates.
The arranged layers of basalt and nanofibrous mats were
then wrapped with plastic bag using a sealant tape (AT200Y,
General Sealants Inc., USA) stacked on square stainless steel
plate with a size of 300×300 mm2. Mixture of epoxy resin
and hardener, which was degassed beforehand using a
dessicator, was then injected at a ratio of 5:1 into the mold at
a pressure of −80 kPa for 45 minutes through a vacuum
pump (Airtech Ulvac G-100D). The prepared panel (i.e.,

molded material) was cured in an autoclave at 65 oC for 2 h.
Measurements and Characterization
The specimens were cut by water jet from the fabricated
panels. Figure 2 shows the schematic layout of the specimen
for tensile (Figure 2(a)) and flexural (Figure 2(b)) tests. The
tensile test and flexural test were conducted according to
ASTM D 638 and ASTM D 790 [38,39], respectively. Five
specimens from each neat and hybrid composite laminate
sample were tested. Tensile testing was carried out using a
universal testing machine (Unitect-M, R&B) at a constant
crosshead speed of 1 mm/min. The strain was measured
through an extensometer with a gage length of 50 mm
(Epsilon Tech. Corp. Model 3542). Flexural testing was
done by a three point bending test, with a support span
length of 32 mm. A 1 mm/min constant strain rate was
maintained in the flexural test until failure of the specimen.
Here, the flexural strength of the sample is the highest stress
prior to failure, and flexural modulus is obtained from the
slope of the straight-line portion of the stress-strain curve
[40]. The average values from five tests for each specimen
and their standard deviations are reported in this study. To
help support the mechanical test results, scanning electron
microscopy (SEM, Jeol, Japan) was carried out to the surface
and cross-section of the neat and composite laminates, as
well as on the nanofibers.

Results and Discussion
Characterization
Figure 3 shows the FE-SEM and TEM images of the
CNTs used in the present study. The CNTs showed smooth
surface with about six concentric layers. The average diameter
of the CNTs was 11 nm, which make them much smaller

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Fibers and Polymers 2014, Vol.15, No.6

than the electrospun fibers, thus making them as good filler
materials. Proper dispersion of CNTs is important to enable
a good load transfer from the polymer to the CNTs, resulting
to improved properties of the composite. In the present
study, the CNTs were dispersed in a solvent solution and
were subjected to bath sonication for one hour. Before
electrospinning, the CNT/DMF/MEK solutions with different
CNT contents were left untouched for at least 2 days to
check the dispersion of the CNTs. We found that the addition
of Triton-X surfactant has aided in the better dispersion of
CNTs without much visible agglomeration and settling down
(results not shown). The other solutions with varying CNT
contents and without surfactant showed some agglomerations
especially at the higher CNT content of 5 wt%. To lessen the
agglomeration during electrospinning, we made sure that
each CNT solution was sonicated for at least 15 min right
before electrospinning.
Figures 4(a) and 4(b) show the morphologies through FESEM and TEM (insets) of the present electrospun nanofibers
made from CNT/PU composites with 3 wt% CNTs without
surfactant, and 3 wt% CNT/PU with surfactant, respectively.
The nanofibrous mats appeared to be white, film-like structure
when viewed visually by the naked eye, however, when
viewed at high magnification using FESEM, it can be seen
that it is highly porous structure, with solid cylindrical
fibers. The addition of different amounts of CNT in the PU

I. D. G. Ary Subagia et al.

nanofiber did not change their morphologies and structure
much, however, less beads could be seen and it can be
noticed that some nodes of nanofibers were bonded together,
which is reported to help in the enhancement of its mechanical
properties. The less beads in CNT/PU nanofibers is attributed
to the increased conductivity of the CNT/PU solution as also
observed by other studies. The TEM images (inset of Figure
4) show some agglomeration of CNTs in the nanofiber, but
less agglomeration was observed when surfactant was added. In
many previous reports, the incorporation of carbon nanotubes
has resulted to increase mechanical and thermal properties of
the composite nanofibers. Others have indicated increased
electrical properties of the composite nanofibrous mat as
well.
To confirm whether CNTs were properly incorporated in/
on the PU nanofibers, Raman spectral analysis was performed
on the fabricated nanofibers (see Figure 5). The prominent
CNT peaks at 1320 cm-1 and 1575 cm-1 correspond to the Dband (associated to defects) and G-band (in plane vibrations)
of the CNTs, respectively [41,42]. Upon checking the Raman
spectra of nanofibers, one can clearly see additional peaks
for the CNT/PU nanofibers compared to the neat PU
nanofibers. The new peaks are attributed to the presence of
the CNTs in/on nanofibers, but slight peak shifts were
observed, signifying interactions such as a newly-formed
hydrogen bonds between PU and the CNTs [43].

Figure 3. (a) FE-SEM and (b) TEM images of the multiwalled carbon nanotubes used in the present study.

Figure 4. SEM images of the electrospun PU nanofibers containing (a) 3 wt% CNT and (b) 3 wt% CNT+surfactant. The insets show their
respective TEM images.

Hybrid Multi-scale Basalt Fiber Composite Laminate

Figure 5. Raman spectra of the present CNTs, neat PU and CNT/
PU composite nanofibers.

Mechanical Properties of Composite Laminates
Figure 6 shows the tensile properties of the present samples
with Figure 6(A) showing the typical load-displacement
curves and Figure 6(B) the average values of tensile strength
and modulus. Table 2 summarizes the mechanical test
results. From Figure 6(A), the tensile curves of the different
samples have a similar characteristic trend. For all cases, the
load of samples increases in a linear manner, and has a high
slope. When the breakage occurred at the maximum point of
load, they suddenly broke off. The composite laminates
containing PU nanofibers with different CNT concentrations
showed higher tensile strengths than the neat basalt/epoxy
laminate (Figure 6(B)). It is worth noting that BPC-4, i.e.,
BFRP added with 3wt% CNT/PU with addition of surfactant
resulted in the highest tensile strength from among all
samples, with a further increase in tensile strain than the neat
BFRP (Figure 6(A)). This is interesting in the sense that both

Fibers and Polymers 2014, Vol.15, No.6

1299

tensile strength and strain were increased. Bortz et al. [44]
also noted the interesting increase in the stiffness, strength
and strain of their composite carbon fiber reinforced
composite (CFRP) laminates when they incorporated 1 wt%
carbon nanofibers. Here, the addition of surfactant helps in
the proper dispersion of CNTs in the nanofiber matrix. It is
well known that effective load transfer from the polymer
matrix to the nanoparticle filler is achieved when the latter is
widely and evenly dispersed in the substrate. In Figure 6(B),
it shows that the incorporation of nanofibers in the laminate
has generally resulted to enhanced tensile strength (~4-13 %
increase) and modulus (~6-20 %) compared to the neat BFRP
(see Table 2). Increasing the CNT content from 1 wt% to
5 wt% in the PU nanofiber also showed increased tensile
strength of the hybrid laminate. However, the BPC-4 (i.e.,
with surfactant) showed the highest increase, which could be
attributed to the more dispersed state of the CNTs in the
nanofiber due to surfactant addition. The better CNT dispersion
lead to effective load transfer of PU matrix to the CNTs, due
to high interfacial stress between the CNTs and PU [41,45, 46].
Figure 7 shows the flexural strength and modulus of the
neat and hybrid composite laminates and the summary of
results are given in Table 2. In the typical stress-strain curves
(Figure 7(A)), the neat BFRP showed the highest flexural
strain but the lowest flexural strength from among the tested
samples. The incorporation of CNT/PU nanofibers in the
BFRP showed increasing flexural strength with the increase
in the amount of CNTs in the nanofibers, however, it also
showed corresponding decrease in flexural strain. All samples
showed linear increasing curves. The neat BFRP had a flexural
strength of 378.70±16.77 MPa, and with the incorporation
of CNT/PU nanofibers with 1 wt%, 3 wt%, and 5 wt%
concentration, and 3 wt% CNT/PU with surfactant, the
flexural strengths obtained were 403.27±20.43 MPa, 418.71

Figure 6. (A) Typical tensile load-extension curves and (B) average tensile strength and modulus of the neat BFRP and hybrid composite
laminates.

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Fibers and Polymers 2014, Vol.15, No.6

I. D. G. Ary Subagia et al.

±26.34 MPa, 421.76±22.23 MPa, and 444.09±23.95 MPa,
respectively (see Figure 7(B) and Table 2). This translates to
an increase of 6.5 %, 10.6 %, 11.4 %, and 17.3 % from that
of the neat BFRP, respectively. Moreover, the hybrid composite
Table 2. Average values of the tensile and flexural properties of the
present neat BFRP and hybrid composite laminates
Specimen

Tensile test
σ (MPa)
E (GPa)
414.27±7.66 17.112±0.208
432.37±15.03 20.528±1.179
435.74±5.50 20.194±0.253
459.19±17.75 18.270±0.406
467.33±18.02 19.347±0.622
tens

BFRP
BPC-1
BPC-2
BPC-3
BPC-4

tens

Flexural test
σ (MPa) E (GPa)
378.70±16.77 15.87±1.36
403.27±20.43 15.91±0.76
418.71±26.34 17.94±1.12
421.76±22.23 18.79±0.66
444.09±23.95 19.20±2.43
flex

flex

laminates showed increasing flexural modulus with the
increase in CNT concentration in PU nanofibers, with BPC4 (i.e., with surfactant) showing the highest increase.
Fracture Surface
Many of the previous reports only focused on the incorporation
of filler materials such as nanoparticles or nanofibers to
provide load transfer from the epoxy matrix [47-49]. However,
very few studies have reported on the multi-scale nanofiller
reinforcements for epoxy matrix in FRP laminates. In this
study, a multi-scale nanofiller reinforcement was provided to
the BFRP with epoxy as its main polymer matrix. Figure
8(a) shows the difference in size scale between basalt fibers
and electrospun CNT/PU nanofibers. The nanofiber, due to
its ultrafine structure as nanofiller could provide very high

Figure 7. (A) Typical flexural stress-strain curves and (B) average flexural strength and modulus of the neat BFRP and hybrid composite
laminates.

Figure 8. SEM images of (a) interleaving of CNT/PU nanofibers on basalt fibers showing difference in sizes; cross-section of fractured
surfaces of (b) BFRP, (c) BFRP with 3 wt% CNT/PU, and (d) BFRP with (3 wt% CNT+surfactant)/PU.

Hybrid Multi-scale Basalt Fiber Composite Laminate

surface area and more reactive sites for complete interaction
with the epoxy matrix, thus can help in improving the
properties of the composite [50,51]. The large surface area
of nanofibers prohibits the epoxy chains from moving freely
as in the case of neat epoxy matrix [52]. The further addition
of much smaller carbon nanotubes inside the nanofibers
could enhance more the mechanical properties of hybrid
material. In this case, load transfer from PU to CNT is
achieved especially when CNTs are uniformly dispersed in
the PU matrix. Additionally, when PU nanofiber is added in
the basalt fiber/epoxy matrix, the PU nanofibers absorbs
some of the loads from the epoxy matrix, thus increasing more
the mechanical properties of the hybrid composite laminate.
In the present study, the same increasing trend results were
seen for both the tensile and flexural strengths of the hybrid
laminates containing CNT/PU nanofibers with different
CNT concentrations. The results could be explained by
investigating what is happening inside the matrix, thus we
obtained SEM images of the cross-sections. Figures 8(b)-(d)
show the cross-sectional images of the samples after
mechanical tests. It can be seen that the neat BFRP (Figure
8(b)) has apparent delaminations and cracks between the
basalt fiber and the epoxy matrix, and cracks in the epoxy
matrix. Basalt fiber pull-outs were also observed indicating
that some basalt fibers were not highly adhered to the epoxy
matrix. Some void areas were also noticed indicating the
non-uniform lamination of some parts leading to decreased
mechanical properties. However, as nanofibers were incorporated
(Figures 8(c) and 8(d)), a more dense and less-void lamination
was observed. Though there were also some delaminations
and crack that occurred especially at the matrix region, no
apparent delamination was observed in the nanofibers zone.
Similar observation was also reported by Liu et al. [53]. The
nanofibers have several folds higher surface area than the
basalt fiber thus, nanofibers provide high surface reactive
area for the epoxy to adhere to. Furthermore, it could be that
some CNTs were protruding from the nanofiber surface thus
giving additional area and anchoring sites for the epoxy
matrix (Figure 8(d)). Adding CNTs into the polymer matrix
restricts the mobility of near interface molecules [54]. This
resulted to increase mechanical strength of the hybrid
composites compared to neat BFRP. When surfactant was
used to dispersed the CNTs in the nanofibers, it gives more
dispersability for CNT and be uniformly distributed in the
PU nanofibers. The better distribution of CNTs in the
nanofibers means better load transfer from PU nanofiber
matrix to CNT. As observed in the Raman spectral analysis
(Figure 5), interactions between CNTs and PU through
possible hydrogen bonding provide effective load transfer
from PU nanofiber to CNTs that enhances the mechanical
properties of the CNT/PU composite compared to the neat
PU alone. Carboxyl groups that are present on CNT surface
can increase the local cross-linking density [54]. Moreover,
there is an additional load transfer from the epoxy matrix to

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1301

the ultrafine, high-surface area CNT/PU nanofibers that are
well-impregnated due to their smaller size [53]. The interaction
between basalt fiber and epoxy resin is not clearly understood,
however, a recent study by Kim [55] showed good interaction
between basalt fibers and epoxy resin, wherein basalt
incorporation limits the mobility of the epoxy polymer chains
and improves the mechanical properties of the whole composite
laminate.

Conclusion
The goal of this study was to develop and evaluate the
mechanical properties of an epoxy-based laminate reinforced
with different filer materials in various scale dimensions
including basalt fibers, electrospun polyurethane (PU)
nanofibers, and carbon nanotubes (CNTs). PU nanofibers
containing different amounts of CNTs were interleaved
between basalt fibers and laminated with epoxy as the
matrix via VARTM. We investigated the effect of multi-scale
reinforcements on the tensile and flexural properties of the
hybrid composite laminates. Different characterization and
mechanical property measurements were carried out on
hybrid composites laminates. Our results indicate increased
tensile and flexural properties when PU nanofibers with
CNTs were incorporated in the hybrid composites compared
to neat basalt fiber-epoxy (BFRP) composite only. Furthermore,
increasing mechanical properties were observed when the
CNT contents in the PU nanofibers were also increased.
When surfactant was used to disperse CNTs in the PU
nanofiber-reinforcements, the maximum increase of 13 % in
tensile strength and 17.3 % in flexural strength compared to
neat BFRP were obtained. The incorporation of PU nanofibers
in the laminate produced more dense epoxy laminate and
more adhered with high surface area nanofibers, leading to
better mechanical properties of the hybrid composite laminate.
The present study presents a facile way to further improve
the mechanical properties of a basalt fiber-epoxy composite
laminate with the use of nanotechnology such as electrospinning
and nanoparticle incorporation.

Acknowledgement
This research was supported by a grant from the Basic
Science Research Program through the National Research
Foundation of Korea (NRF) funded by the Ministry of
Science, ICT and Future Planning (2010-0022359).

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