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ADVANCES in NATURAL and APPLIED SCIENCES
ISSN: 1995-0772 Published BYAENSI Publication EISSN: 1998-1090 http://www.aensiweb.com/ANAS
2017 June 11(8): pages 73-81 Open Access Journal
ToCite ThisArticle: A. Balaji, B. Karthikeyan, J. Swaminathan, C. Sundar Raj., Mechanical and thermal properties of Untreated bagasse fiber reinforced cardanol Eco-friendly biocomposites. Advances in Natural and Applied Sciences. 11(8); Pages: 73-81
Mechanical and thermal properties of Untreated bagasse fiber reinforced cardanol Eco-friendly biocomposites
1A. Balaji, 2B. Karthikeyan, 3J. Swaminathan, 4C. Sundar Raj
1Assistant Professor, Department of Mechanical Engineering, A.V.C. College of Engineering, Mayiladuthurai, TamilNadu, India - 609 305. 2Associate professor, Department of Mechanical Engineering, Faculty of Engineering and Technology, Annamalai University, Tamil Nadu, India - 608 002. 3Associate professor Department of Chemistry, A.V.C. College of Engineering, Mayiladuthurai, TamilNadu, India - 609 305. 4Professor & Head, Department of Mechanical Engineering, A.V.C. College of Engineering, Mayiladuthurai, TamilNadu, India - 609 305. Received 28 February 2017; Accepted 22 May 2017; Available online 6 June 2017
Address For Correspondence: A.Balaji, Assistant Professor, Department of Mechanical Engineering, A.V.C. College of Engineering, Mayiladuthurai, TamilNadu, India 609 305. E-mail: [email protected]
Copyright © 2017 by authors and American-Eurasian Network for ScientificInformation (AENSI Publication). This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/
ABSTRACT A growing worldwide trend for utmost use of natural property through novel processes and products has enhanced studies and examination of renewable eco-friendly materials. In this work, the sugarcane bagasse fiber was used as a source of grasses fibers filler to fabricate a new type of successful biodegradable composite, based on the cardanol, a component of the cashew nut shell liquid (CNSL), as a fully biodegradable thermosetting polymer matrix. For the bio-composite preparation, several blends were prepared with varying ratios of filler and matrix. The composites were prepared in fiber average length of 10 mm and different contents of 0, 5, 10, 15 and 20 (Wt%), mechanical and thermal studies were characterized. The effects of fiber loading on the thermal properties of ecological bio polymer composites were evaluated by thermal gravimetric analysis (TGA). Scanning Electron Microscopy (SEM) was used for morphological studies. The chemical configuration of the new biocomposites was also analyzed by means of the Fourier Transform Infrared (FT-IR) spectroscopy technique. TG results showed that among biocomposites, the one reinforced by sponge gourd fibers had the highest thermal stability, in addition to the greatest performance in the tensile testing. The bio based thermosetting plastic and biocomposites showed an excellent potential to a number of applications, such as manufacturing of articles for furniture and automotive industries. SEM images showed that the mercerization process induced a roughness onto the fiber surface, good incorporation, dispersion, and adhesion to polymer matrix.
KEYWORDS: Bio-composites, Bagasse fiber, Cardanol resin, Thermal strength, Mechanical Strength
INTRODUCTION
Polymeric composites may be understood as the blend of two or more materials, for example, reinforcement
elements or filler occupied by a polymeric matrix [1]. The introduction of synthetic fibers and/or natural fibers
(Chemical treated or unteated) into a polymer is known to cause substantial changes in the resulting composites
[2], which may result, in a different way from the original materials, in renewable, environmentally friendly,
production of natural fibers - annual renewability and lower energy inputs in production per unit, commonly
known processing methods, excellent specific strength and high modulus, reduced density of products, lower
cost, corrosion resistance,high creep resistance, high toughness, biodegradable and some biocomposites can
have much higher wear resistance than metals [3]. However, the main drawback of natural fibers is their
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74 A. Balaji et al., 2017/Advances in Natural and Applied Sciences. 11(8) June 2017, Pages: 73-81
hydrophilic nature that lowers the compatibility with hydrophobic polymeric matrices during composite
fabrication [4].
Numerous natural fibers have been used in automobiles, trucks, and railway cars [5]. Natural fibers for
example jute, sisal, bagasse, pineapple, abaca and coir [6-7] have been studied as reinforcement and filler in
composites. Amongst those, bagasse is as the remains from the extraction of juice from the sugarcane and has
been used as a combustible material for energy supply in sugarcane factories, as a pulp raw material in paper
industries and as a reinforcing material for fiber board [8]. However, few studies on the biodegradable
composites reinforced with bagasse fiber have been reported.
Growing concerns about the environment and sustainability are fueling in increasing global investigate
effort devoted to understand and by means of renewable resources. The aim is to decrease the dependence on
fossil fuels, which are rapidly being exhausted and to develop novel technologies and aggressive industrial
commodities. Vegetable oils are abundant and low-cost renewable resources which stand for a major potential
another source of chemicals appropriate for developing environmentally protected and user friendly products.
As well as it attracted the attention for providing source materials for a multitude of plastic products some
outstanding properties such as better mechanical and thermal stability.
Cashew Nut Shell Liquid (CNSL) is a versatile by-product of the cashew industry. CNSL has numerous
applications in polymer based industries such as friction linings, paints and varnishes, laminating resins, rubber
compounding resins, cashew cements, polyurethane based polymers, surfactants, epoxy resins, foundry
chemicals and intermediates for chemical industry. It offers much scope and varied opportunities for the
development of other biopolymer composites [9 -10]. And also it has been found to possess excellent flame
retardants behaviour; however the inherent toxicity of brominated compounds limits the use of these materials in
flame retardants applications [11].
The aim of this work is (1) to prepare bagasse fiber (Cut 10 mm length); (2) to make bio-composite
materials from thermosetting cardanol–formaldehyde resin with bagasse fibers as reinforcement in different
weight percentages; (3) to examine the mechanical and thermal properties of the bio-composite materials.
MATERIALS AND METHODS
1.1. Materials:
CNSL were obtained from Ganesh Chemicals (Pondicherry, India) Formaldehyde, epoxy, HY 951, and
Sodium hydroxide was purchased from Indian scientific solution (Mayiladuthurai, Tamil Nadu India). The
sugarcane bagasse collected from roadside sugarcane juice shop at Chidambaram, (Cuddalore District, Tamil
Nadu, India).
1.2. Methods:
Sugarcane baggase was dried in the sunlight for 16 hours to remove moisture content from it. After that the
sugarcane baggase was placed in the hot air oven at 90 to 1000 C for 24 hours to remove the moisture content
completely. Then, the fibers were cut into 10 mm length transversally. The single fiber cross-sectional
geometry, in common, may not be circular. But, it is normally assumed to be circular in cross-section [12].
Figure 1 shows the photograph of the prepared bagasse fibers.
2. Composites preparation:
The prepared 10 mm length bagasse fibers were mixed with the prepared Cardanol in our earlier work,
epoxy resin and hardener matrix in a ratio of 3: 8: 1. The mixture was shifted to a mould in dimension of 300 ×
300 × 3 mm and was fabricated. The material was next taken into the compression moulding machine. By
compression moulding process, under temperature of 110°C and pressure of 100 kgf, the laminate was formed.
The laminates were left to cure at 60 to 70°C temperature for 24 hours in hot air oven. The different weight
composition fibers, viz., 0, 5, 10, 15, and 20 Wt% were presented in Table 1. and Figure 2 shows the photograph
of the developed composites.
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Fig. 1: Sugarcane Bagasse Fiber
Fig. 2: Photograph of the developed composites
Table 1: Compositions of investigated systems
R1 Cardanol + Epoxy + 0 Wt% Bagasse fiber
R2 Cardanol + Epoxy + 5 Wt% Bagasse fiber for 10 mm length
R3 Cardanol + Epoxy + 10 Wt% Bagasse fiber for 10 mm length
R4 Cardanol + Epoxy + 15 Wt% Bagasse fiber for 10 mm length
R5 Cardanol + Epoxy + 20 Wt% Bagasse fiber for 10 mm length
2.1. Measurements:
The tensile strength measurement experiments were performed on Unitek - 94100 testing machine at a load
range 0 to 100 kN and cross head speed of 5 to 250 mm/min. For tensile tests, the composite samples were cut
into dumb-bell shape with cross sectional dimension of 150 X 15 X 3.0 mm in accordance with ASTM D638.
The tests were carried out five times to report the average value.
Hardness values of the bio composites was determined by Rockwell hardness machine RAB 250 SCNO :
SN 7078 using a 1.56 mm steel ball indenter, minor load of 10 kgf, and major load of 100 kgf.
A Scanning Electron Microscope (SEM) JEOL JSM 6610 LV was used to scan the surface morphology of
the tensile fracture surface samples. The samples were washed, cleaned thoroughly, air-dried and were coated
with gold to provide enhanced conductivity and observed SEM at 15 kV.
Thermogravimetry (TGA) techniques were used to analyze the thermal stability of fibers and composites.
All the measurements were performed using a TA Instruments NETZSCH STA 449F3 thermo gravimetric
analyzer. Samples weighing between 10 and 20 mg were placed in a platinum pan and tests were carried out in a
programmed temperature range of 30/20.0(K/min)/600.
The FT-IR spectra analysis was carried out by Bruker IFS 66 infra-red spectrophotometer, using KBr pellet,
in the infrared spectra. All the samples were recorded in the region 4000 – 400 cm-1. The spectral measurements
were carried out at Annamalai University, Annamalai Nagar, India.
RESULTS AND DISCUSSION
3.1 Density:
Density is one of the most essential mechanical properties of the element board material. The density of
untreated 10 mm length bagasse fiber reinforced composite for various Wt % of fiber. The fundamental method
of determining the density of composite samples by determining the weight and volume of the sample was used
[13].
Formula used for Density = weight/volume (1)
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76 A. Balaji et al., 2017/Advances in Natural and Applied Sciences. 11(8) June 2017, Pages: 73-81
A sample is weighed in the digital weighing balance machine and evaluates the weight of the sample. The
density of the sample was calculated from the equation below. From Figure 3, it was found that the composite
density increased from 0.8735 g/cm3 to 1.17641 g/cm3 with increasing of Wt % bagasse fibers.
0 5 10 15 20
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
Den
sity
( g
/cm
3 )
Wt % of Bagasse Fiber
10 mm Length bagasse Fiber
Fig. 3: Variation of density with Wt % bagasse fiber
3.2 Hardness:
The results of hardness values are shown in Figure 4, it was observed that with increase in Wt% bagasse
fiber in the Cardanol-Epoxy resin matrix, the hardness values of the composites increases. E.g. hardness values
of 26 HRB and 43 HRB (see Figure. 4). The increments were credited to an increase in the percentage of the
hard and brittle bagasse fiber as exposed by the composition of the bagasse fiber [14]. Also the differences in
coefficient of thermal expansion (CTE) between the bagasse fiber and polymer matrix resulted in elastic and
plastic incompatibility between the matrix and the bagasse fiber [15]. In comparison with the unreinforced
Cardanol-epoxy matrix, a substantial improvement in hardness values was obtained in the reinforced Cardanol-
epoxy matrix.
0 5 10 15 20
20
22
24
26
28
30
32
34
36
38
40
42
44
Hard
nes
s (
HR
B )
Wt % of Bagasse Fiber
10 mm Length bagasse Fiber
Fig. 4: Variation of Hardness with Wt % bagasse fiber
3.3 Tensile strength:
Figure 5 shows the photograph of the tensile specimen of before and after fracture. Figure 6 shows the end
product of fiber content on the tensile strength and modulus of untreated bagasse fiber composites. In keeping
with the general rule of mixtures, the tensile strength of composites increased from 18.6 to 24.4 MPa with
increase in the fiber content (Wt%) from 0 to 15%. However, the tensile strength decreased to 23.4 MPa even
though increase in the fiber content to 20 Wt%. The highest value was observed at 15 Wt%. The tensile modulus
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of composites increased from 1.15 to 2.34 Gpa with increase in the fiber content (Wt%) from 0 to 20%.
Investigational data shows a poor interaction between fibers and matrix during the mixture process. Composites
were obtained with uniform distribution, but with agglomerations in some points caused by incompetent fibers
distribution inside matrix. This agglomeration of reinforcement was responsible by decrease of the tensile
strength compared to the high density resin [16].
Fig. 5: Photograph of the tensile specimen of before and after fracture
0 5 10 15 20
18
20
22
24
Tensile Stress for 10 mm Length Fiber
Tensile Modulus for 10 mm Length Fiber
Wt % Bagasse Fiber
Ten
sile
Str
ength
(M
pa)
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
Ten
sile Mod
ulu
s (Gp
a)
Fig. 6: Variation of Tensile strength and Modulus with Wt % bagasse fiber
3.4 Morphology of the blends:
Figure 7 represent the tensile fractured region, where it was confirmed fibers distribution in the matrix,
fibers fractured in the matrix and pull out fibers, characterizing mechanism of brittle fracture. It was also
observed that energy dissipation during the frictional process mechanics. Figure 7 (a) showing confirmation of
no voids and absence of fibers. The SEM image of tensile fractured surface of the virgin Cardanol and epoxy
was relatively soft and flat, though it had some matrix deformation and ridges as seen from Figure 7(b), which
represent its large brittle nature with some inadequate ductility [17].
Fiber pull out was the deciding factor and the failure mechanism may be due to the cracks being easily
propagated through void regions of 5 Wt% fiber content composites in Figure 7(b). The morphology of 10 Wt %
fiber content composites established in Figure 7(c) shows individual separation and dispersion of the bagasse
fibers within the Cardanol epoxy matrix which might have happened during the compression moulding process.
The SEM image of 15 Wt % fiber content composites exhibited in Figure 7(d) showing evidence for the matrix
deformation, fiber fracture instead of fiber drawn out [18] indicating minimum porous nature, no fiber
aggregation and fiber was evenly distributed within the Cardanol epoxy matrix imparting improved interfacial
adhesion between them. It also reveals to the enhancement in tensile properties of the 15 Wt % fiber content
composites. Figure 7(e) 20 Wt% show traces of matrix still adhering into and around the fiber. The fiber failure
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mode even shows the cellulose microfibrils still surrounded by the matrix and also considerable amount of
fibers tearing was also noticed [19].
Fig. 7: SEM fractograph of tensile specimen of (a) 0 Wt % fiber content, (b) 5 Wt % fiber content, (c) 10 Wt %
fiber content, (d) 15 Wt % fiber content and (e) 20 Wt % fiber content.
Thermal analysis:
4.1Thermogravimetric analysis (TGA):
The thermal degradation and stability were determined by Thermogravimetric Analysis (TGA). TG curves
of bagasse fiber reinforced cardanol epoxy resin biocomposites with different fiber contents are presented in
Figure 8. Cardanol epoxy resin showed a one-step decomposition process, while composites clearly showed a
two-step process. The initial weight loss (4.5%) between 31 and 160°C corresponds to the vaporization of water
(OH) from the fibers. The thermal degradation of bagasse fiber was due to the decomposition of lignin, cellulose
and hemicelluloses to give off volatiles [20 - 21]. Above this temperature, thermal stability is gradually
decreasing and decomposition of fibers occurs. The TG curve of Cardanol epoxy resin starts to decompose at
about 480 °C. The mass loss of Cardanol epoxy resin in a one-step degradation procedure starts at about 480 °C
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and beyond this stage increasing the temperature upto 700°C, this progression occurs quickly. Finally, the
residue amount of Cardanol epoxy resin was 13.4% because of its further breakdown into gaseous products at
high temperature. In TG curve, it clearly shows that the thermal stability of biocomposites declined as the
bagasse fiber content increased. The thermal degradation of the composites with various fiber contents (5-20%)
takes place in a two-step degradation process. Besides, mainly due to the decomposition of bagasse fiber, this
biocomposites exhibited initial mass loss (4.4%) from approximately room temperature to 154°C may be due to
the devolatilization of moisture of bagasse fibers incorporated into the Cardanol epoxy resin composite. Then
the second stage of thermal degradation step, which mainly related to Cardanol epoxy resin degradation,
overlapped with cellulose and lignin content in bagasse fiber is observed. Among, the various fiber content
composite with Cardanol epoxy resin, the 15 Wt % of bagasse fiber is the best composite. Because, the residue
value (17%) is higher than that of 0 Wt % of bagasse fiber and also, this two-step degradation process
demonstrates that the thermal degradation temperature of the Cardanol epoxy resin is higher than of the bagasse
fiber.
0 100 200 300 400 500 600 700
10
20
30
40
50
60
70
80
90
100
110
Wei
gh
t (%
)
Temperature (°C)
0 Wt % fiber
5 Wt % fiber
10 Wt % fiber
15 Wt % fiber
20 Wt % fiber
Fig. 8: Thermogravimetric curves of composites of different composition
4.2 FT-IR spectroscopy:
The FT-IR spectra for the laminates of Cardanol, epoxy and bagasse fiber in different percentage
composition, viz., 0%, 5%, 10%, 15% and 20% (Table 1) were taken and the comparison was shown in Figure
9. The FT-IR spectra of all the above mentioned percentages were well correlated with each other. The FT-IR
spectra of all the laminates was analysed thoroughly.
The most sensitive O-H group vibration shows the shifts in the spectra of the hydrogen-bonded species.
Usually, hydrogen bond free O-H stretching frequency will be observed around 3700 cm-1 [22]. In our study, a
broad spectrum at 3300 cm-1 shows the shift of O-H stretching vibration, which clearly indicates the presence of
inter-molecular hydrogen bonding [23 -24]. This inter-molecular hydrogen bonding between the cardanol resin
and the cellulose present in the bagasse fiber shows the strengthenss of the laminates.
The presence of CH2 stretching in the cardanol resin was indicated by a strong peak around 2900 cm-1. The
medium band around 1700 cm-1 shows the presence of C=O stretching vibration [24], which highlight the
existence of acidic functional group of the cellulose present in the bagasse fiber. A strong band and a medium
band observed around 1500 and 1450 cm-1 respectively indicates the C-C stretching vibration in both bagasse
and cardanol resin. The presence of C-O stretching vibration in fiber and resin was pointed out by a medium
band observed around 1250 cm-1. The two weak bands appear near 1100 and 1000 cm-1 specifies the C-H
outplane bending vibration. Another medium peak at 800 cm-1 shows the existence of C-C-C in-plane bending
of aromatic ring present in the cardanol resin.
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4000 3500 3000 2500 2000 1500 1000 500
-20
0
20
40
60
80
100
120
140
160
180
200
Tra
nsm
itta
nce
%
Wavenu mber /(cm-1)
0 Wt % fiber
5 Wt % fiber
10 Wt % fiber
15 Wt % fiber
20 Wt % fiber
Fig. 9: FT-IR spectra of composites of different composition
Conclusions:
The successful use of cardanol for the development of a thermosetting matrix reinforced by bagasse fibers
was investigated. 15 Wt % presented the greatest performance in Tensile testing and good incorporation,
dispersion, and addehesion with Cardanol epoxy matrix, observed by SEM. Hardness is uniformly increased
with increase in Wt% of bagasse fiber reinforcement. And also TG results showed that among biocomposites,
that one reinforced by bagasse fibers 15 Wt% had the highest thermal stability. The FT-IR analysis of the
laminates shows the existence of inter molecular hydrogen bonding of the cellulose in baggase fiber and
cardanol resin which indicates the strength of the laminates irrespective of the composition.
This paper provided useful information and introduced the biocomposites prepared from a combination
between a cardanol-based resin and bagasse fibers by a low-cost processing and characterization of a thermoset
plastic and which showed a good potential to several applications, from manufacturing of articles to furniture
and automotive industries.
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