Abstract: The coconut shell powder reinforced polypropylene (CS-PP) composite was prepared. The thermogravimetric analysis of the coconut shell powder (CS), polypropylene (PP) and CS-PP composites was carried out. The mechanical properties of coconut shell reinforced polypropylene composite have been investigated to establish the feasibility of using it as a new potential raw material for various engineering related applications. CS-PP composite was prepared by compounding polypropylene matrix with 20% -60 % volume fraction of coconut shell powder. The effect of the CS powder loading on thermal and mechanical properties of the obtained CS-PP plastic composite was also investigated. The 20% weight ratio of CS powder reinforced CS-PP plastic composite shows the superior mechanical properties

S Karuppuchamy

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International Journal of ChemTech Research
                                CODEN (USA): IJCRGG ISSN: 0974-4290
                               Vol.8, No.6, pp  852-857, 2015
Thermo-mechanical properties of coconut shell powder
reinforced plastic composites
S. Karuppuchamy
Department of Energy Science, Alagappa University, Karaikudi,
Tamil Nadu- 630 003, India
Abstract: The coconut shell powder reinforced polypropylene (CS-PP) composite was
prepared. The thermogravimetric analysis of the coconut shell powder (CS), polypropylene
(PP) and CS-PP composites was carried out. The mechanical properties of coconut shell
reinforced polypropylene composite have been investigated to establish the feasibility of
using it as a new potential raw material for various engineering related applications. CS-PP
composite was prepared by compounding polypropylene matrix with 20% - 60 % volume
fraction of coconut shell powder. The effect of the CS powder loading on thermal and
mechanical properties of the obtained CS-PP plastic composite was also investigated. The
20% weight ratio of CS powder reinforced CS-PP plastic composite shows the superior
mechanical properties.
Keywords: Biocomposites; Coconut Shell; Mechanical property.
1. Introduction
In recent years, composite materials have gained much importance due to its numerous distinctive
features that benefit the society. The composite material can be prepared by mixing two or more materials
which often have very different properties. The composite materials have the potential to use in many different
industries. Composites are exceptionally lightweight and extremely strong, especially per unit of weight [1-10].
Among the existing composites, the natural fiber reinforced biocomposites have attracted much interest due to
its advantages such as light as well as strong. Agricultural wastes such as oil palm empty fruit bunch, coconut
fiber, sugarcane bagasse, rice husk and straw have attracted much attention in the past several years due to its
large abundance and their applications in polymer based biocomposites [11–22]. Agricultural based plant fiber
biocomposites have variety of attractive properties over the existing conventional composites. The plant fiber
reinforced biocomposites have very good mechanical behaviors, cheap, low density, considerable processing
advantages and outstanding resistance to chemicals. Among the agricultural based fibers, coconut shell (CS) is
considered to be one of the potential smart lignocellulosic materials because of their availability and low
production cost [21, 22]. It is interesting that the coconut shell powder has great potential as reinforcement in
plastic composites. The oily nature of coconut shell powder provided a strong interfacial bonding between the
fiber and polymer matrix [23, 24]. We made an attempt to use the agro-based coconut shell particles as
reinforcement with polypropylene matrix. In this work, coconut shell powder and polypropylene were used to
fabricate the plastic composites with the aim of exploring coconut shell as potential reinforcement filler for
polypropylene matrix. We prepared the CS-PP plastic composites and also investigated the effects of various
amount of CS powder filler loading on thermal and mechanical properties of CS-PP composite.
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S. Karuppuchamy /Int.J. ChemTech Res. 2015,8(6),pp 852-857. 853
2. Experimental
2.1 Materials
All the chemicals were purchased from commercial sources and were the highest purity available. The
coconut shell was collected from Coimbatore, Tamilnadu, India. The collected coconut shell was crushed into
powder. The milled CS powder was sieved into size distributions in the range of 75-150μm. The sieved powder
was dried in oven at 70°C before using for further process.
2.2 Preparation of CS-PP Plastic Composites
       The composites were prepared by the melt blending of CS powder and polypropylene (PP) in a
Brabender internal mixer at 180°C with a rotor speed of 100 rpm. The ratio of CS/PP was fixed at four different
ratios such as 20/80, 40/60, 50/50 and 60/40. Briefly, PP pellets were first melted in the Brabender mixing
chamber for 2 min and then the CS powder was added slowly into the mixing chamber and mixed for another
13 min. The compounded materials were compressed into sheets with thickness of 1 and 3 mm by hydraulic
hot-press at temperature of 180 °C for 5 min followed by cold pressing at 30 °C for 5 min.
2.3 Characterization
The crystallinity of the CS powder was measured using Wide-angle X-ray diffraction (WAXD) (Rigaku
Corporation, Japan) with Cu Kα radiation source. Thermogravimetric analysis (TGA) was carried out using TG
analyzer model EXSTAR6000 TG/DTA6200 (Hitachi, Japan) in order to confirm the change in the composition
of the CS powder and CS-PP biocomposites. The CS powder sample was placed on an aluminum pan and then
the sample was heated from 50–550 °C at a heating rate of 10 °C/min under nitrogen flow of 100 mL/min. The
corresponding weight loss (μg) and its derivative DTG (μg/min) were recorded. Tensile testing was carried out
on the CS-PP biocomposites according to ASTM D638-V using Instron 4302 Universal Testing Machine.
Flexural tests were conducted using IMC-18E0 Model Machine (Imoto Machinery Co., Ltd, Japan). Flexural
properties were measured in accordance with the procedure in JIS K 7171 at a cross head speed of 5 mm/min
with  a  span  of  20  mm.  Tests  were  carried  out  for  at  least  five  specimens  to  obtain  a  consistent  average  and
standard deviations. Flexural and tensile tests were performed at room temperature.
3. Results and discussion
3.1 X-ray Diffraction Analysis
The XRD pattern of CS powder is shown in Fig.1. The noticeable strong crystalline peak of CS powder
was observed at around 2q = 22.5º. The observed peak could be assigned to the crystallographic plane of
cellulose materials of CS Powder.
Fig.1. XRD patterns of CS powder                          Fig. 2. FT-IR spectra of CS powder
S. Karuppuchamy /Int.J. ChemTech Res. 2015,8(6),pp 852-857. 854
3.2 FTIR Analysis
Fourier transform infrared (FTIR) spectroscopy is one of the important techniques used to determine
the molecular structure of biological samples and recently it has been applied to detect and identify the tree
species (cellulosic materials) and microbial strains [25]. Figure 2, illustrates the FTIR spectrum of CS powder.
The FTIR spectrum was recorded as the transmittance (%) versus frequency in the range of 4000 – 400 cm-1
(Fig. 2). The spectrum demonstrates many number of absorption peaks representing the presence of various
groups in the samples. The FTIR spectrum of CS powder show bands at around 1730 and 1248 cm-1, which
corresponds to the stretching vibration of >C=O and > C-O groups, respectively [26]. These groups are exist in
lignin and hemicelluloses structure of natural lignocellulosic fibers due to >C=O peak (1739 cm-1 and the FTIR
study indicates that the simple physical treatment (grinding) does not eliminate the lignin or hemicelluloses
from the coconut shell powder.
3.3 Thermogravimetric analysis
The studies on thermal behaviour of CS powder is important in order to find out the filler’s stability in
reinforced-polymer composite processing because the processing temperature for many polymeric materials
exceeds over 180 °C. The thermogram and DTA curve of CS powder, PP, CS powder reinforced PP composites
are shown in Fig. 2 and 3. The TG curve of CS powder clearly indicates the weight loss at different temperature
region. The first weight loss occurred at around 100ºC may be due to the evaporation of absorbed moisture. The
occurrence of weight loss can be seen from 220 to 315°C. The degradation of CS powder at various temperature
region clearly demonstrated that the continuous degradation of several components. The weight loss in the
temperature range of 240 - 350 °C could be due to the degradation of hemicelluloses and cellulose [14]. The
DTG curve of CS powder also confirms the degradation of hemicelluloses and lignin (Fig. 4). The TGA curve
of polypropylene shows the degradation from at around 350°C. It is very interesting to note that the degradation
temperature of CS-PP plastic composites enhanced depends upon the addition of CS powder loading on the
composite as shown in Fig. 3 and 4.
Fig. 3. TGA curves of CS powder, PP and              Fig. 4. DTG curves of CS powder, PP and CS-PP
CS-PP plastic composites                                          plastic composites
3.4. Effect of CS powder loading on the mechanical properties of the composite
Recent research on natural fiber reinforced composites found that the loading of fillers plays a significant
role in enhancing the mechanical properties of natural fiber reinforced plastic composites. CS-PP plastic
composites were prepared using four different weight ratios of CS powder in combination with PP and
investigated the effect of powder loading on the mechanical properties of the CS-PP plastic composites. We
prepared the plastic composites using the CS powder in the weight ratio of such as 20%, 40% and 60% in
combination with PP. Figure 5 and 6 shows the tensile strength and young’s modulus of the tested composite
materials, respectively. Tensile strength and modulus of the CS-PP plastic composites linearly decreases while
increasing the weight of CS powder content in the composite. The tensile strength of the CS powder reinforced
S. Karuppuchamy /Int.J. ChemTech Res. 2015,8(6),pp 852-857. 855
PP plastic composite has dramatically decreased when the loading of CS powder has increased more than 40%
as compared to the bare PP. However, the tensile modulus of the composites does not decrease much compared
to the bare PP. This decrease in tensile strength may suggest that there is no effective transfer of stress from the
CS  powder  to  the  PP  matrix.  It  has  been  reported  that  the  addition  of  filler  into  the  polymer  matrix  always
reduces the tensile strength and that can be improved by the addition of some compatibilizers during the
composite preparation [11].
Fig. 5. Tensile strength value of biocomposites made of CS powder/PP (20:80 v/v), (40:60 v/v) and (60:40
v/v) in comparison with PP
Fig. 6. Young’s Modulus value of biocomposites made of CS powder/PP (20:80 v/v), (40:60 v/v) and
(60:40 v/v) in comparison with PP
Figure 7 and 8 shows the flexural test results of the fabricated CS-PP plastic biocomposites. The
results show the higher flexural strength and flexural modulus values for CS-PP composites compared to bare
polypropylene. Further, the flexural test was carried out on the obtained CS -PP biocomposites to understand
the effect of filler loading on the mechanical properties. The flexural strength and flexural modulus of CS-PP
biocomposites are higher when the CS powder loading is 20% compared to the higher weight ratio of CS
powder loading. This may be attributed to the increase of interfacial bonding strength between the CS filler and
polypropylene matrix at optimum loading (20%). Further optimization of the size of the CS powder and
addition of compatibilizer are expected to improve the mechanical properties of this green composite. The
tensile and flexural test results clearly indicate that the increase of interfacial bond strength between the CS
powder and polypropylene matrix at the optimum CS powder loading with PP composites. This study indicates
that the CS powder is a potential replacement for the natural fiber to use as filler in the polymer composites.
S. Karuppuchamy /Int.J. ChemTech Res. 2015,8(6),pp 852-857. 856
Fig. 7. Flexural Modulus value of biocomposites made of CS powder/PP (20:80 v/v), (40:60 v/v) and
(60:40 v/v) in comparison with PP
Fig. 8. Flexural strength value of biocomposites made of CS powder/PP (20:80 v/v), (40:60 v/v) and (60:40
v/v) in comparison with PP
4. Conclusions
The CS powder has been used to blend with polypropylene to achieve CS-Polypropylene plastic
composites. Various weight contents (20 - 60%) of the CS powder were reinforced in the polypropylene matrix.
The effect of the fiber weight contents on thermal and mechanical properties of the obtained CS-PP plastic
composite was investigated. The young’s modulus, flexural strength and flexural modulus values of the CS
powder reinforced CS-PP composites were the highest compared to the bare PP composites at optimum loading
of the CS filler.
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Thermo-mechanical properties of coconut shell powder reinforced plastic composites

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Thermo-mechanical properties of coconut shell powder reinforced plastic composites

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