International Journal of Mechanical Engineering and Technology (IJMET)
Volume 10, Issue 01, January 2019, pp. 1383–1391, Article ID: IJMET_10_01_140
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=1
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
Scopus Indexed
TENSILE, IMPACT, FLEXURAL AND
MORPHOLOGICAL CHARACTERISTICS OF
PINEAPPLE LEAF FIBER REINFORCED
POLYLACTIC ACID COMPOSITES
Darsan R S
Department of Mechanical Engineering
Noorul Islam Centre for Higher Education, Kumaracoil, India
Stanly Jones Retnam. B
Department of Automobile Engineering,
Noorul Islam Centre for Higher Education, Kumaracoil, India
M Sivapragash
Department of Mechanical Engineering, PSN College of Engineering and Technology,
Melathediyoor, Tirunelveli 627152, Tamil Nadu, India
* E-mail: ndmresearch11@gmail.com
ABSTRACT
The composites are fabricated by reinforcement of various fibre composition of
short natural fibre into polylactic acid (PLA) by compression moulding. Untreated
pineapple (UPAL) and treated pineapple (TPAL) fibres are used as reinforcement
material to prepare composites of 10%, 15% and 20% fibre loadings. Tensile, impact,
flexural and morphological characteristics conducted on different fibre loaded
UPAL/PLA and TPAL/PLA composites. Tensile strength has increased to 40.78% and
44.33% for 10% fibre loaded UPAL/PLA and TPAL/PLA composites respectively. A
similar increase in tensile modulus of 20.8% and 11.47% for 20% fibre loaded
UPAL/PLA and TPAL/PLA composites respectively. The significant increase is noted
for the flexural strength and the flexural modulus of UPAL/PLA and TPAL/PLA
composites. Impact strength increases with increase in fibre loading. Ductile fracture
is noticed in UPAL/PLA composites, while brittle fracture is inferred in TPAL/PLA
composites from the SEM images.
Key words: Tensile, impact, flexural and morphological characteristics, untreated and
treated natural fiber and polylactic acid.
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Darsan R S, Stanly Jones Retnam. B, M Sivapragash
Cite this Article: Darsan R S, Stanly Jones Retnam. B, M Sivapragash, Tensile,
Impact, Flexural and Morphological Characteristics of Pineapple Leaf Fiber
Reinforced Polylactic Acid Composites, International Journal of Mechanical
Engineering and Technology 10(1), 2019, pp. 1383–1391.
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=1
1. INTRODUCTION
The immense volume of petroleum-based thermoplastic polymers are used in day to day
applications in the form of household appliances to industrial products. The decomposition
and degradation of non-renewable based synthetic polymers raises more significant
challenges and leads to environmental pollution in the form of accumulation of solid waste
pollutes the water bodies [1]. Incineration of these waste leads to the generation of toxic gases
which in turn pollutes the air. Both methods of waste disposal are not feasible as it causes a
high level of environmental pollution. In recent years more awareness is created among
people and communities to use products that are from environmentally friendly materials.
In current scenario the attention of the communities has shifted to the materials which are
naturally degradable without affecting the ecosystem. Thus, the search for materials has
culminated in the polymers which has natural roots. A new generation of polymers known as
‘green’ polymers formed from the renewable natural roots [2] can be a replacement for the
existing polymers. Various consumer products produced in large volumes started depending
on ‘green’ polymers. During the recycling process of the green polymers, the enzymatic
biocatalyst in them works to return them to the carbon cycle [3,4].
Currently, the research for modern materials is directed in developing sustainable
materials to create an ecological balance to the nature. Such materials will be mostly a
biocomposite, formed from a combination of the green polymer matrix and is reinforced with
natural fillers [5]. The biocomposites are produced from polymers coming from natural
renewable roots, which should have a capacity to replace the existing petroleum-based
nonrenewable polymers. There are various verities of polymers made from renewable sources
like starch, cellulose and proteins etc. Examples of such naturally occurring polymers are,
polylactic acids (PLA), synthesized from lactide monomers, polyhydroxybutyrate produced
through microbial fermentation [6]. Among the renewable biopolymers, polylactic acids are
biodegradable, obtained through agricultural roots, and they have properties nearer the
existing used polymers [7]. The reinforcement filler materials are natural fibres produced
from plant and animal [8]. Few of the natural fibres like cotton [9], jute [9], ramie [10],
bamboo [11], kenaf [12] and sisal [13] were used as reinforcement in the PLA matrix for
fabrication of green composites. Appreciable changes in properties are noticed in pineapple
leaf fibre (PAL) reinforced with polyester composites due to their higher percentage of
cellulose content [14]. The alkali treatment helps to remove the hydrophobic waxy layer thus
improving the wettability of the matrix with the fibre [15].
In the present study tensile, impact, flexural and morphological characteristion of
pineapple leaf fibre reinforced polylactic acid composites prepared by compression moulding.
Evaluate the effect of different fibre loading on short treated and untreated fibre on the
properties of the composites, prepared using compression moulding technique and
morphological characteristics using SEM to understand the fracture behaviour of the
composites.
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Tensile, Impact, Flexural and Morphological Characteristics of Pineapple Leaf Fiber Reinforced
Polylactic Acid Composites
2. MATERIALS & EXPERIMENTAL PROCEDURES
2.1. Materials
From Nature Works, USA PLA 3052D grade Polylactic acid is procured. Pineapple leaf fibres
are obtained from Vrushacomposites and services, India, Sodium hydroxide (NaOH) pellets
and Glacial Acetic acid are from SRL chemicals and HIMEDIA, India.
2.2. Treatment on Pineapple Leaf Fibre
Initially, the pineapple leaf fibre is washed in mild detergent followed by in distilled water to
remove any leftover detergent. Secondly, the washed fibres were rinsed in distilled water is
dipped in for 2 hours in sodium hydroxide solution of 2% concentration under room
condition[15]. The fibres were then washed in distilled water, followed by immersion in
glacial acetic acid of 1% concentration, and washed in distilled water to remove any traces of
acid. Finally, the fibres are air dried in shade till the entire water content is removed. The
dried fibres are cut into 3 -6mm in length.
2.3. Composite Preparation
The first step in composite preparation is to dry the PLA and PAL fibres in hot air oven at
80OC for few hours to remove the moisture content. The second step is melt blending of PLA
and untreated PAL fibres (UPAL) & treated PAL fibres(TPAL) using (M/s. Specific
Engineering, ZV 20, Baroda India) a twin screw extruder for 0%, 10%, 15%, 20% fibre
loadings. The blended materials are initially cooled and pelletised using a shredding machine.
The pelletised shredded materials are dried overnight in a hot air oven at 80OC. Dried
pelletised material is formed into a sheet of 200 X 200 X 3.2mm using a compression
moulding machine. From the compresson moulded sheets standard specimens are cut.
3. MECHANICAL TESTING
3.2. Tensile testing
The tensile testing is carried out using Universal testing machine (M/s. Tinius Olsen, H
50KL) according to ASTM D638 with a crosshead speed of 5mm/min, on a gauge length of
50mm, to find out the tensile property of various samples prepared.
3.3. Flexural testing
The flexural test is conducted to find the flexural strength and flexural modulus on the
universal testing machine according to the ASTM D790 standard.
3.4. Impact testing
The impact strength of the samples was found using impact tester (M/s. Tinius Olsen, Impact
104), according to the ASTM D256 standard.
3.5. Morphological characteristics
The fracture behaviour of fractured specimens is observed by Scanning electron microscopy
(SEM), M/s. TESCAN VEGA 3 SBH with a resolution of 10nm.
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4. RESULT & DISCUSSION
4.1. Mechanical Properties
4.1.1. Tensile Properties of UPAL/PLA and TPAL/PLA Composites
The tensile strength and modulus of untreated pineapple leaf fibre (UPAL)/Polylactic acid
(PLA) and treated pineapple leaf fibre (TPAL)/Polylactic acid (PLA) composites of different
fibre percentage loadings are shown in figure 1 and figure 2 respectively. From figure 1, there
is a sharp increase of 40.78% in strength for 10% fibre loading for UPAL/PLA composite
when compared with the virgin PLA. For 15% and 20% fibre loaded UPAL/PLA composite
the tensile strength has an increase of 24.2% and 20.92% respectively with repect to virgin
PLA. In the case of TPAL/PLA composites, for 10% fibre loading an increase of 44.33%,
8.1% and 15.25% increase respectively for 15% and 20% fibre loading with respect to virgin
PLA. The tensile modulus of the UPAL/PLA composites shows an increase of 6.93%, 12%
and 20.8% respectively for 10%, 15% and 20 % fibre loading with respect to virgin PLA. In
the case of TPAL/PLA composites, a decrease of 4.27% for 10% fibre loading and an increase
of 0.27% and 11.47% respectively for 15% and 20% fibre loading with respect to virgin PLA.
Agglomeration at higher loading fraction resulted in decrement of strength at higher loading
fraction [16].
Figure 1 Tensile Strength of UP AL/PLA and TPAL/PLA composites
Figure 2 Tensile Modulus of UPAL/PLA and TPAL/PLA composites.
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Polylactic Acid Composites
4.1.2. Impact strength of UPAL/PLA and TPAL/PLA composites
The impact strength of UPAL/PLA and TPAL/PLA composites for different fibre percentage
compositions are shown in Figure 3. For different fibre loading of UPAL/PLA and
TPAL/PLA composites, shows similar behaviours. The impact strength increases up to 15%
fibre loading and shows a decrease for 20% fibre loading. In the case of UPAL/PLA
composites, an initial increase of 8.46% and 28.67% for 10% and 15% fibre loading with
respect to virgin PLA and a decrease of 6.29% for 20% fibre loading when compared with
15% fibre loaded composite. For TPAL/PLA composites, 10.66% and 41.18% increase
respectively for 10% and 20% fibre loaded composite when compared with virgin PLA and a
decrease of 1.30% for 20% fibre loading with repect to 15% TPAL/PLA composite.
Introduction of more and more stiffer fiber into the matrix resulted in increase in impact
strength at higher loading fractions [17].
Figure 3 Impact of UPAL/PLA and TPAL/PLA composites.
4.1.3. Flexural Properties of UPAL/PLA And TPAL/PLA Composites
Figure 4 Flexural strength of UPAL/PLA and TPAL/PLA composites
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The flexural strength and modulus of UPAL/PLA and TPAL/PLA composites for
different fibre percentages in compositions are represented in Figure 4 and Figure 5
respectively. The 10% fibre loading of UPAL/PLA composites has a decrease of 2.99%
strength with respect to virgin PLA and for 15% and 20% shows an increase of 9.3% and
9.072% with respect to virgin PLA. For TPAL/PLA composites, for various fibre loading
initial increase in flexural strength followed by a decline as the fibre loading increases. The
maximum flexural strength of 27.38% increase is shown for 10% fibre loading and 23.83%
and 22.19% increase corresponding to 15% and 20% fibre loading when compared with
virgin PLA. In the case of flexural strength, the maximum flexural strength for both
UPAL/PLA and TPAL/PLA composites with different fibre loading is exhibited by 20% fibre
loaded com posites. An increase of 22.38% and 13.75% respectively for 20% fibre loaded
UPAL/PLA and TPAL/PLA composite when compared with virgin PLA. In the case of
UPAL/PLA composites an initial increase of 19.05% for 10% fibre loading and a decrease of
1.04% for 15% fibre loading with respect to virgin PLA. For TPAL/PLA composites shows
an initial decrease of 0.51% for 10% fibre loading and an increase of 5.44% for 15% fibre
loading compared to virgin PLA.
Figure 5 Flexural Modulus of UPAL/PLA and TPAL/PLA composites.
4.1.4. Morphological Properties of UPAL/PLA And TPAL/PLA Composites
Figure 6, 7, 8 & 9 shows the SEM images of 10% and 15% UPAL/PLA and TPAL/PLA
composites respectively. From figure 6, the fracture is the result of ductile fracture and poor
interfacial bonding between the untreated fibre and the PLA matrix. In the case of the 15%,
the nature of the fracture is brittle and other reasons resulted in fracture during loading are
poor interfacial bonding between fibre and matrix and fibre pull out. Figure 8 shows the
fracture behaviour of 10% TPAL/PLA composite, which is similar to 10 % UPAL/PLA
composite, with void present along the matrix. For 10% TPAL/PLA composite, fracture
happen due to various causes, like matrix crack, fibre pullout, a large number of voids, poor
interfacial bond between fibre and matrix and the nature of the fracture is brittle.
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Tensile, Impact, Flexural and Morphological Characteristics of Pineapple Leaf Fiber Reinforced
Polylactic Acid Composites
Figure 6 SEM images of 10 % UPAL/PLA
composite.
Figure 7 SEM images of 15% UPAL/PLA
composite.
Figure 8 SEM images of 10 % TPAL/PLA
composite.
Figure 9 SEM image of 15% TPAL/PLA
composite.
5. CONCLUSIONS
In this research work on composites prepared by reinforcement of pineapple fibre in both
untreated and treated condition into the PLA matrix, tensile, impact, flexural and
morphological properties of % UPAL/PLA and TPAL/PLA composites are analysed.
The following conclusions are noted in this work.

UPAL and TPAL fibres are reinforced into PLA matrix initially using a twin extruder,
followed by compression mouldinginto sheets. The standard specimens for each
characterisation are cut from the compression moulded sheets.
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Darsan R S, Stanly Jones Retnam. B, M Sivapragash

The decrease in tensile strength for higher fibre loading in UPAL/PLA composites due to
agglomeration and poor interfacial bonding between the UPAL fibre and PLA matrix, this was
evident from the SEM images. Brittle fracture and matrix crack resulted in variation of
properties exhibited in TPAL/PLA composites. The tensile modulus increases the increase in
fibre loading for both UPAL/PLA and TPAL/PLA composites due to the introduction of stiff
fibre into the PLA matrix.

The impact strength in both UPAL and TPAL fibre reinforced composites increases up to to
15% fibre loading followed by reduction due to agglomeration of the fibre in the PLA matrix
for higher fibre loading.

Variation in flexural strength and modulus of UPAL/PLA and TPAL/PLA composites are due
to the non-uniform orientation of fibre in the PLA matrix during compression moulding.

Brittle fracture, fibre pull out, matrix crack and numerous voids present on the matrix
attributed to the reduction in properties of TPAL/PLA composites at higher loading fractions.
ACKNOWLEDGEMENTS
The authors are grateful to CIPET: Institute of Plastics Technology (IPT), and Maharaja’s
College, Ernakulam in conducting different characterisations.
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