Elaboration of properties of graphene oxide reinforced epoxy nanocomposites

TLDR: In this paper, the properties of graphene oxide (GO) based epoxy nanocomposites, prepared via the solution blending method, are elaborated Different loadings (1 −05 ¼ ) of GO were added into epoxy resin, and their effects were studied on their surface reaction, morphology, mechanical and thermal properties.

Abstract: In this research work, properties of graphene oxide (GO) based epoxy nanocomposites, prepared via the solution blending method, are elaborated Different loadings (01–05 wt%) of GO were added into epoxy resin, and their effects were studied on their surface reaction, morphology, mechanical and thermal properties It was found that a chemical modification, layer expansion and dispersion of filler within the epoxy matrix resulted in an improved interface bonding between the GO and epoxy matrix The optimum amount of graphene nanostructures can be useful to improve the properties of epoxy nanocomposites for applications in adhesives to automotive

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BARI, P., KHAN, S., NJUGUNA, J. and MISHRA, S. 2017. Elaboration of properties of graphene oxide reinforced epoxy
nanocomposites. International journal of plastics technology [online], 21(1), pages 194-208. Available from:
https://doi.org/10.1007/s12588-017-9180-9
This is a post-peer-review, pre-copyedited version of an article published in International Journal of Plastics
Technology. The final authenticated version is available online at: https://.doi.org/10.1007/s12588-017-9180-
9. This pre-copyedited version is made available under the Springer terms of reuse for AAMs.
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https://openair.rgu.ac.uk
Elaboration of properties of graphene oxide
reinforced epoxy nanocomposites.
BARI, P., KHAN, S., NJUGUNA, J. and MISHRA, S.
2017

Elaboration of properties of graphene oxide reinforced epoxy nanocomposites
Pravin Bari
1
, Samrin Khan
1
, James Njuguna
2
, Satyendra Mishra
1
*
1
University Institute of Chemical Technology, North Maharashtra University,
Jalgaon-425001, Maharashtra, India
2
School of Engineering, Robert Gordon University, Riverside East,
Aberdeen, AB10 7GJ, United Kingdom
Abstract
In this research work, properties of graphene oxide (GO) based epoxy nanocomposites,
prepared via the solution blending method, are elaborated. Different loadings (0.1–
0.5 wt%) of GO were added into epoxy resin, and their effects were studied on their
surface reaction, morphology, mechanical and thermal properties. It was found that a
chemical modification, layer expansion and dispersion of filler within the epoxy matrix
resulted in an improved interface bonding between the GO and epoxy matrix. The
optimum amount of graphene nanostructures can be useful to improve the properties of
epoxy nanocomposites for applications in adhesives to automotive.
Keywords
Graphene Epoxy Nanocomposites Preparation Mechanical and thermal properties
Introduction
Graphene, new carbon material, based nanocomposites have attracted considerable
attention and have shown an immense interest due to their unique properties [1] It has
a wide potential applications in energy related systems, mainly because of its unique
atom-thick two dimensional structure [2, 3], high thermal conductivity [4, 5],

mechanical stiffness [6, 7], electronic transport properties [8, 9, 10, 11], optical and
chemical performance [12] as well as multi layer hybrid nano structures [13]. However,
the stronger hydration and easier dispersion of GO in water are observed; while GO
was prepared by the Modified Hummers method [14, 15, 16]. GO prepared from
graphite flakes can be used on a large scale for preparation of graphitic films and as a
binder for carbon products [17]. Silva et al. [18] concluded from their experiment that
the graphene/epoxy nanocomposite shows rise in working temperature and durability
of composite and also observed improvement in mechanical properties. Sharmila et al.
[19] reported that the combination of good processing properties with enhanced
mechanical and dielectric properties makes GO great candidate to develop
multifunctional polymer nanocomposites which has sought extensive application in
electromagnetic interference shielding (EMI), conductive adhesives and for thermal
conductivity enhancement. GO was also used as modifying agent and graphene layer
also prepared by oxidation [20, 21]. Fracture toughness of carbon-graphene/epoxy
hybrid nanocomposites has also been studied. Graphene has two dimensional structure
can be used in its both forms, i.e. in its oxidized form and in its reduced form [22, 23].
As the oxidized form of graphene have functionality linked up and it provides insulating
characteristics, while the reduced form of graphene contains no functionality or some
amount of functionality [24, 25, 26]. Graphene can be synthesis by chemical vepor
deposition and arc discharge method [27, 28]. This can provide to it conducting nature
used for increasing conductivity of the matrix in which it is incorporated. It can be said
that the graphene as nanofiller has an application from insulator to conductor [29, 30].
Graphene made of atomically thin carbon sheets also improves physical properties of
host polymers [31, 32, 33, 34].
Epoxy resin is considered one of the most versatile thermoset materials, which has
applications in several fields due to its excellent adhesion, electrical insulating,
mechanical and thermal properties, as well as, chemical and heat resistance. However,
epoxy resins are generally brittle which restrict their applications. Hawkins et al. [35,
36] studied the fracture toughness and strain energy behavior of carbon-graphene/epoxy
hybrid nanocomposites. GO-epoxy based nanocomposites also possess the flexural
behavior. [37]. Ribeiro et al. [38] studied the glass transition improvement in graphene-
epoxy composites. Multi-nanostructured (clay and graphene platelets) reinforced epoxy
nanocomposites have been also studied by Zaman et al. [39]. Mechanical and thermal

properties of epoxy composites containing GO and liquid crystalline epoxy have also
been studied [40].
In the present work we have focused to reinforce the GO in epoxy resin by solution
blending method using acetone as diluent for epoxy. The resulting epoxy
nanocomposites were characterized by FESEM, FTIR, XRD, EDX and DSC. Different
properties were studied to probe the effect of the nanofillers on the mechanical and
thermal properties of the composites. The elemental mapping of the composites was
done to understand the GO dispersion in epoxy.
Experimental
Materials
Graphite powder (98%), from Lobel Chemical, Ortho-phosphoric acid (H
3
PO
4
, 85%)
and Hydrogen Peroxide(H
2
O
2
, 30%) were purchased from Lobel chemical and Merck
specialist Pvt. Ltd. Mumbai, India; Sulfuric acid (H
2
SO
4
, 97%), Potassium
permanganate (KMnO
4
, 99.9%), petroleum ether, Hydrazine Hydrate, Acetone and
Ethanol (AR grade) were purchased from Rankem Thane, Maharashtra, India. Reactive
diluents RD-113, Epoxy resin grade YD128 of EEW-189.5, viscosity 11,000–14,000
cp were procured from Aditya Birla Groups Mumbai, India. Curing agent Diethylene
Triamine (DETA purity) was purchased from s. d. Fine. Chemicals Limited, Mumbai,
India.
Synthesis
Preparation of GO
Graphite powder (5.0 gm) was mixed into the solution of concentrated H
2
SO
4
and
H
3
PO
4
taken in 9:1 ratio (600:66.66 mL). Sulfuric acid intercalated GO has also been
prepared [23]. Meanwhile, 8–9 time weight equivalent KMnO
4
(30.0 gm) powder was
also added to graphite mixed solution. This reaction mixture was then heated in three
necked flask fitted with water cooled condenser having temperature below 50 °C and
allowed to stir continuously for 12 h. The reaction mixture was cooled to room
temperature and then kept in ice bath after the addition of 30% H
2
O
2
. Resulting
suspension was filtered through polyester fiber cloth and remaining filtrate was
centrifuged at 4000 rpm. The supernatant solution was decanted and residual solid

material was washed with water, 30% HCl, distilled water and finally with ethanol. The
solid material was coagulated with 200 mL of PET ether and vacuum-dried overnight
at room temperature. In this manner several batches were carried out for bulk
preparation of GO.
Preparation of graphene-epoxy nanocomposites
Solution blending method was used for nanocomposite preparation of graphene-epoxy
nanocomposites. Graphene oxide was taken into varying amounts from 0.1 to 0.5 wt%.
Total 55 g was the amount of all compositions of epoxy nanocomposites. Epoxy resin
was taken into prescribed amount (Table 1) then acetone was added into the resin to
lower down its viscosity. Then GO was sonicated for 30 min. The GO dispersion was
mixed into the resin under high speed for 45 min and mixed with ethanol in the said
ratio then kept it at 80 °C in an oil bath till the solvent evaporation. Then the mixture
was sonicated for 30 min and then 10 phr DETA (5.56 g) was added to the mixture
(Fig. 1). The mixture was poured into the mould, degassed for 1 h and then cured at
room temperature for 2–3 days. Samples were cut for further mechanical and thermal
testing.
Table 1
Amount of ingredients required for preparation of epoxy nanocomposites
Sr.
No.
GO (wt.%) in resin
nanocomposites
Epoxy resin (wt.%) in
resin nanocomposites
Amount of
GO (gm)
Amount of
resin (gm)
1
0.1
99.9
0.055
54.975
2
0.2
99.8
0.110
54.890
3
0.3
99.7
0.165
54.835
4
0.4
99.6
0.220
54.780
5
0.5
99.5
0.275
54.725

Frequently asked questions

Q1. What are the contributions in this paper?

In this research work, properties of graphene oxide ( GO ) based epoxy nanocomposites, prepared via the solution blending method, are elaborated. Different loadings ( 0. 1– 0. 5 wt % ) of GO were added into epoxy resin, and their effects were studied on their surface reaction, morphology, mechanical and thermal properties. 

Q2. What is the effect of adding GO to the epoxy matrix?

Further addition of GO results decrement in mechanical properties, which is due to the presence of large aggregates and some defects of the nanoreinforcements formed on the surface during sample preparation as well. 

Q3. How many scans were taken for each nanocomposite sample?

Total 45 scans were taken for each nanocomposite sample recorded at 4000–400 cm−1 with resolution of 4 cm−1 in the transmittance mode. 

Q4. What is the FTIR spectra of graphite oxide?

FTIR spectra of GO-epoxy nanocomposites a 0.5, b 0.4, c 0.3, d 0.2, e 0.1 wt% of GOThe characteristic features in the FT-IR spectrum of GO are absorption bands corresponding to C=O carboxyl 1721 cm−1, the C–OH stretching at 1371 cm−1, and the C–O stretching at 1117, 3412 cm−1 is due to the stretching vibration of hydroxyl group. 

Q5. How many wt% of GO are added to the epoxy?

The values of hardness are recorded as 75, 78, 79, 80, 84 and 79 for virgin epoxy 0.1, 0.2, 0.3, 0.4 and 0.5 wt% GO filled composites respectively. 

Q6. What is the method to reinforce GO in epoxy?

In the present work the authors have focused to reinforce the GO in epoxy resin by solution blending method using acetone as diluent for epoxy. 

Q7. How many wt% of GO is added to the epoxy matrix?

It is already reported in the text that the addition of nanofillers to the epoxy matrix, up to 0.4 wt% GO exhibites highest mechanical properties. 

Q8. What was the peak temperature of the epoxy composites?

All samples showed a single exothermic peak at a temperature, more than 300 °C, originating from the decomposition of functional groups on GO in the epoxy-based composites. 

Q9. How long did the reaction mixture take to cool?

This reaction mixture was then heated in three necked flask fitted with water cooled condenser having temperature below 50 °C and allowed to stir continuously for 12 h. 

Q10. What was the spectroscopic method used for the analysis of epoxy nanocomposites?

Fourier transform infrared (FTIR) spectroscopySamples of the GO and epoxy nanocomposites were finely divided and dispersed in a KBr powder for analysis. 

Q11. What is the effect of the GO on the thermal stability of the epoxy?

As reported earlier that the thermal stability of the composites is effected by the treatment and addition of fillers [41, 42, 43], the GO also effects the thermal decomposition behavior of the epoxy. 

Q12. What is the difference between graphene and epoxy?

The higher level of improvement offered by GO is attributed to the strong interaction of graphene sheets with epoxy because the covalent bonds between the carbon atoms of graphene sheets are much stronger than other layered nanomaterial such as silicon-based clay. 

Q13. What is the tensile strength of the virgin epoxy composites?

6Tensile strength And Young modulus of GO-Epoxy compositesLike tensile strength, the vaues of young’s modulus were also recorded to increase up to 750 MPa at 0.4 wt% of GO in epoxy (Fig. 6).