Toughness Properties of Nanostitched and Nanoprepreg Carbon/Epoxy Materials

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Volume 1- Issue 2 - November 2017
DOI: 10.19080/CTFTTE.2017.01.555557
Curr Trends Fashion Technol Textile Eng
Copyright © All rights are reserved by Bilisik K
Toughness Properties of Nanostitched and
Nanoprepreg Carbon/Epoxy Materials
Bilisik K1*, Erdogan G1, Karaduman N2, Sapanci E3 and Gungor S3
1Department of Textile Engineering, Erciyes University, Turkey
2Akdagmadeni Vocational High School, Bozok University, Turkey
3ROKETSAN Industries, Elmadag-Ankara, Turkey
Submission: September 22, 2017 Published: November 10, 2017
*Corresponding author: Bilisik K, Department of Textile Engineering, Faculty of Engineering, Erciyes University, 38039 Talas-Kayseri, Turkey,
Email:
Curr Trends Fashion Technol Textile Eng 1(2): CTFTTE.MS.ID.555557 (2017) 001
Introduction
Textile composites have been used in various space-
aerospace, ballistic and medical areas due to their high stiffness
to weight ratio and damage tolerance properties. Recently,
nanosphere, single wall or multiwall tubes were employed in

various techniques [1]. Single wall carbon nanotubes (SWCNTs)
or MultiWall Carbon Nano Tubes (MWCNTs) have become an
important industrial material especially in the use of advanced
       
mode-I fracture toughness and tension-bearing [3,4]. The
objective of this study was to develop nano stitching/nano
prepreg carbon/epoxy composites and to examine the fracture
toughness of those structures.
Materials and Methods
Nanostitching/nanoprepregcarbon/epoxy preform
and composite
Polyacrylonitrile (PAN) carbon woven fabrics (Spinteks
A.S., TR) were used to make nanopreform. The multiwall
carbon nanotubes (MWCNTs, Nanothinx, GR) were selected
based on compatibility with the carbon fabric. Basically, three
types of carbon structures were developed: 1) base (CTU, CSU);
2) base/nano (CTU-N, MWCNTs prepreg; CSU-N, MWCNTs
prepreg); 3) stitched/nano (CT-CS-N, PAN carbon nanostitched/
nanoprepreg; CT-TS-N, para-aramid nanostitched/nanoprepreg;
CS-CS-N, PAN carbon nanostitched/nanoprepreg; CS-TS-N,
para-aramid nanostitched/nanoprepreg). MWCNTs (0.03125,
%wt., Nanothinx, GR) were added to epoxy resin (Araldite
LZ 5021, Biester feld Spezialchemie GmbH, DE) after series of
magnetic mixing and ultrasonic mixing and vacuuming to get
homogeneous dispersion. The matrix was applied to the carbon
fabric and stitching yarnsto make nano prepreg fabric and nano
stitching yarn, respectively. The four layered prepregnanocarbon
preform was stitched by carbon or para-aramid nanostitching
yarn. The nanostiched/nanoprepreg preform was consolidated
by using the compression molding.
Mode-I interlaminar fracture toughness (Gic) test
The mode-I interlaminar fracture toughness (GIC) of the
base, base/nano, and stitched/nano structures was measured
using the Double Cantilever Beam (DCB) test specimen. We
followed ASTM Standard D5528-01.The delaminated areas and
damaged surfaces of the composite sample were examined by a
scanning electron microscope (SEM, LEO 440® model, UK).
Results and Discussion
We started by selecting 0.5% (weight %) ratio for the
MWCNTs as an initial condition. Later on, a large agglomeration
(about 200-300 microns) of nanotubes was found in the epoxy.
Extensive studies were conducted to decrease the size of the
agglomeration of the nanotubes. For this reason, we decreased
the MNCNT ratio and increased the stirring time in ultrasonic
mixing. Therefore, the size of the agglomeration of carbon
nanotubes decreased to 30-80 microns in the epoxy (Figure
1(a)). The MWCNT added epoxy was applied to the stitching yarn
(Figure 1(b)) and fabric (Figure 1(c).
Mode-I fracture toughness results
The average fracture toughness GIC max (BT) and (MBT)
values of the stitched/nano structures showed an almost 3 fold
(283%) and over a 2 fold (225%) increase compared to the base
or base/nano structures (Figure 2), respectively. It was realized
that stitching and nano increased the fracture toughness GIC
max of all the stitched/nano composites. At the declamination

direction was obtained to support declamination resistance. The
nanostitching yarn under the declamination load was stressed
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How to cite this article: Bilisik K, Erdogan G, Karaduman N, Sapanci E, Gungor S. Toughness Properties of Nanostitched and Nanoprepreg Carbon/
Epoxy Materials. Curr Trends Fashion Technol Textile Eng. 2017; 1(2): 555557. DOI: 10.19080/CTFTTE.2017.01.555557.
002
Current Trends in Fashion Technology & Textile Engineering
        
the nanostitching yarns were broken in their straight portion.
Around the nanostitching yarn region, crack propagation was
severely arrested.
Figure 1: (a) Nanoepoxy resin; (b) nanostitchingyarn; (c) nanoprepregfabric surface (Optic microscope, magnication x4, x4, x1, respec-
tively).
Figure 2: Interlaminar fracture toughness (GIcmax, kj/m2) and crack length (a, mm) results for nanostitched/nanoprepreg carbon/epoxy
composites.
Failure after DCB test results
Uniform declamination growth was observed parallel to the
mid-plane warp near to the mid-plane of the base (CSU and CTU)
structures (Figure 3(a-c)). However, minor rough crack growth
    
direction. Both the base and base/nano structures had a sharp
crack tip. Long smooth crack propagation was achieved near
to the mid-plane of the stitched/nano (CS-TS-N) composites in
the warp directions. Short length rough crack propagation was


declamination front (Figure 4(a-b)).
Figure 3: (a) Delamination growth failure in CSU; (b) crack failure in CTU; (c) delamination failure in CSU-N (optical microscope, magni-
cation x6.7).

003 How to cite this article: Bilisik K, Erdogan G, Karaduman N, Sapanci E, Gungor S. Toughness Properties of Nanostitched and Nanoprepreg Carbon/
Epoxy Materials. Curr Trends Fashion Technol Textile Eng. 2017; 1(2): 555557. DOI: 10.19080/CTFTTE.2017.01.555557.
Current Trends in Fashion Technology & Textile Engineering
Figure 4 : (a) Delamination growth failure in CSU; (b) crack failure in CTU; (c) delamination failure in CSU-N (optical microscope, magni-
cation x6.7).
Beam arms failure at the declamination front of stitched/
      
toughness load, declamination crack growth was arrested by

direction. When the nanostitching yarn strength was well above
the top layer structure strength, “beam arms failure” occurred
in the top layer which was to some extent related to the bending
strength (Figure 5(a)). Most of the warps next to the interlocking
loops of the paraaramid nanostitching yarn were simultaneously
broken in the width direction of the structure (CS-TS-N) (Figure
5(b)).
Figure 5 : (a) Beam arms failure in CS-TS-N; (b) top view of severe crack failure during DCB test in CS-TS-N (optical microscope, magni-
cation x6.7).
Conclusion
The mode-I interlaminar fracture toughness (GIC max) of the
stitched/nano structures showed an almost 3 fold (283%, beam

compared to the base or base/nano structures. Stitching and
nanotubes increased the fracture toughness strength of all
stitched/nano composites. The stitched/nano structure had
     
       
       

in stitched/nano structures axially split and they had ductile

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25th International Conference on Composites or Nano Engineering
(ICCE-25) Italy, pp. 1-2.

How to cite this article: Bilisik K, Erdogan G, Karaduman N, Sapanci E, Gungor S. Toughness Properties of Nanostitched and Nanoprepreg Carbon/
Epoxy Materials. Curr Trends Fashion Technol Textile Eng. 2017; 1(2): 555557. DOI: 10.19080/CTFTTE.2017.01.555557.
004
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DOI: 10.19080/CTFTTE.2017.01.555557