Effect of nano SiO2(13.69nm)with different weight percentage (1, 3, 5wt %)on some mechanical properties of polylactic acid (PLA) is investigated .PLA film with thickness 100µm was prepared by solution casting method .Chemical and crystal structure of PLA and its composites with 5% nano SiO2 are characterized by FTIR and X-ray diffraction techniques .

1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 2, February (2014), pp. 01-07, © IAEME
1
EFFECT OF NANO SiO2 ON SOME MECHANICAL PROPERTIES OF
BIODEGRADABLE POLYLACTIC ACID
Nadia Abbas Ali1
, Ikram Atta AL-Ajaj1
, Farah Tariq Mohammed Noori1
1
Baghdad University, college science, physics Department
ABSTRACT
Effect of nano SiO2(13.69nm)with different weight percentage (1, 3, 5wt %)on some
mechanical properties of polylactic acid (PLA) is investigated .PLA film with thickness 100µm was
prepared by solution casting method .Chemical and crystal structure of PLA and its composites with
5% nano SiO2 are characterized by FTIR and X-ray diffraction techniques . Mechanical properties
(tensile strength and young modulus) of PLA and its composites are reported .Enhancement in above
mechanical properties are observed (35%for tensile strength and 25%for young modulus). The main
goal of this work is to study the influence of addition of different silica nanoparticles on the
mechanical properties of neat PLA in order to enhance its for brittleness to ductile stage.
Key Word: Biodegradable, Polylactic Acid, nano SiO2, Mechanical Properties.
1-INTRODUCTION
Natural polymers that are biodegradable and biocompatible has become increasingly
important. This is due to their amazing characteristics: natural abundance, low costs and wide range
of applications [1]. These polymers are being widely used in the biomedical area, including wound
dressing, drug delivery system and tissue engineering scaffolds . Polylactic acid (PLA) is prominent
among the polymers that are biodegradable and biocompatible due to versatility of its applications
and relatively low cost of production at industrial scale. PLA, is a linear aliphatic thermoplastic
polyester, produced from renewable resources, has several attractive properties such as
biocompatibility, high strength, and thermo plasticity. It has been used in medical applications, such
as surgical sutures, implants, tissue culture, and controlled drug delivery. Though PLA is
biodegradable and has been useful in various biomedical applications, the high stiffness and
brittleness at ambient temperatures associated with PLA must be improved to allow for more
applications [2,3]
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2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
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The applications of nanomaterial
food packaging technology. It also could provide an antimicrobial mechanism by introducing nano
bulletin active packaging. The most popular purpose of this nano
reinforcement in composite polymer in fact, many studies on nano
Nano-reinforcement that's been studied
2- EXPERIMENTAL WORK
1. Materials
Polylactic acid (PLA) (ESUN™ A
Industrial Company. Ltd (Shenzhen, China .
particle size (13.69 nm)is shown in Fig(1)
Fig(1) Granuality normal distribution chart for nano SiO
2. Preparation of PLA film and PLA
Neat PLA film is prepared by weight 2gm of PLA in 20 ml of chloroform
composites with different weight percentage
casting method in chloroform. Silica was added in chloroform and stirr
min. Nanoparticles were dispersed in the solvent using ultrasonic bath. Then PLA was added to
solvent/silica mixture and stirred with magnetic bar for 4 h hours at 40°C. After dissolving in
chloroform, PLA/silica nanocomposites were poured into glass Petri dishes (10 cm diameter) and
vacuum dried for 2h and, additionally, 24 hours for total evaporation of solvent at room
The films were peeled off with thickness
3. (FT-IR) TEST
FT-IR was performed using a Perkin Elmer 1600 Infrared spectrometer. FT
samples were recorded by using Nicolet’s AVATAR 360 at 32 scans with a resolution of 4 cm
within the wave number range of 4000 to
4. X-ray Diffraction TEST
X-ray Diffraction patterns were measured in
using target Cu Kα ( λ= 1.54A° ) with secondary monochromator (Karlsruhe, Germany)
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
6359(Online), Volume 5, Issue 2, February (2014), pp. 01-
2
of nanomaterial are broad; some of them were used as nano
food packaging technology. It also could provide an antimicrobial mechanism by introducing nano
bulletin active packaging. The most popular purpose of this nano material is widely used as nano
mposite polymer in fact, many studies on nano reinforcement were reported.
reinforcement that's been studied is such as clay and silicates [4].
Polylactic acid (PLA) (ESUN™ A-1001) [density = 1.25 g/cm3
was supplied by Bright China
Industrial Company. Ltd (Shenzhen, China .NanoSiO2 supplied by Sima-aldrch
s shown in Fig(1)measured by (SPM) of nano SiO2 .
Granuality normal distribution chart for nano SiO2 particl
film and PLA/ nano SiO2 composites film.
prepared by weight 2gm of PLA in 20 ml of chloroform
percentage of nanosilica (1,3,5wt %) were prepared by solution
casting method in chloroform. Silica was added in chloroform and stirring in ultrasonic bath for 10
min. Nanoparticles were dispersed in the solvent using ultrasonic bath. Then PLA was added to
ed with magnetic bar for 4 h hours at 40°C. After dissolving in
chloroform, PLA/silica nanocomposites were poured into glass Petri dishes (10 cm diameter) and
vacuum dried for 2h and, additionally, 24 hours for total evaporation of solvent at room
thickness around 100µm.
IR was performed using a Perkin Elmer 1600 Infrared spectrometer. FT-IR spectra of the
samples were recorded by using Nicolet’s AVATAR 360 at 32 scans with a resolution of 4 cm
within the wave number range of 4000 to 400 cm-1.
patterns were measured in a Brüker Advance instrument, at 40 KV, 40 mA
with secondary monochromator (Karlsruhe, Germany)
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
-07, © IAEME
of them were used as nano-sensor in smart
food packaging technology. It also could provide an antimicrobial mechanism by introducing nano-
material is widely used as nano
reinforcement were reported.
supplied by Bright China
aldrch Company with
particles
prepared by weight 2gm of PLA in 20 ml of chloroform, PLA films
%) were prepared by solution
in ultrasonic bath for 10
min. Nanoparticles were dispersed in the solvent using ultrasonic bath. Then PLA was added to
ed with magnetic bar for 4 h hours at 40°C. After dissolving in
chloroform, PLA/silica nanocomposites were poured into glass Petri dishes (10 cm diameter) and
vacuum dried for 2h and, additionally, 24 hours for total evaporation of solvent at room temperature.
IR spectra of the
samples were recorded by using Nicolet’s AVATAR 360 at 32 scans with a resolution of 4 cm-1 and
a Brüker Advance instrument, at 40 KV, 40 mA
with secondary monochromator (Karlsruhe, Germany).

3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
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5. Tensile Properties
Mechanical test was performed
strength at the point of breakage for each sample. Tensile
at room temperature, according to the ASTM D
composites(1,3,5wt% ) respectively
and the results were taken as an average of five tests
both ends of the test specimen of the film.
determined according to the following equation
Where: F: force exerted on an object under tension,
L: length of the object changes
Fig(2) : samples of
3. RESULTS AND DISCUSSION
1. (FT-IR) characterization
FT-IR is a well-known and widely used method to investigate the intermolecular
and phase behavior between the polymers. In this study, the interaction between PLA
investigated by FT-IR spectroscopy and is shown in Figure
in (Fig 3(a)) clearly show the characteristic absorpt
2946- 2999 cm-1 and 1757cm-1due to O
stretching vibration and C=O stretching vibration
FTIR of PLA film reported by Cardoso, J. J. F.
bonds of PLA and SiO2 appear that mean good distribution of nano SiO2
that bond appear and no different in pure PLA
a
a
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
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3
performed using the Instron 4400 Universal Tester to measure the tensile
strength at the point of breakage for each sample. Tensile specimens cut were used
at room temperature, according to the ASTM D-882 as shown in Fig 2a pure PLA , b, c, and d
. A fixed crosshead rate of 10 mm/min was utilized in all cases
and the results were taken as an average of five tests. Two metallic grips were attached for griping
both ends of the test specimen of the film. Tensile strength (σs), Young’s modulus
according to the following equation:
σs =F /(A)……… 1
E =F L0/A L…………2
: force exerted on an object under tension, L0: original length, A: cross section area,
samples of PLA and its composites (1,3,5%) nano SiO2
3. RESULTS AND DISCUSSION
known and widely used method to investigate the intermolecular
and phase behavior between the polymers. In this study, the interaction between PLA
IR spectroscopy and is shown in Figure( 3) . FTIR spectrum of neat PLA
the characteristic absorption bands in the region of 3500
1due to O-H bending and stretching vibration, C
stretching vibration and C=O stretching vibration respectively, which agree well with the prepared
Cardoso, J. J. F.et. al., [5]. Fig3b is appear of PLA/5%SiO
appear that mean good distribution of nano SiO2 in composites film
that bond appear and no different in pure PLA .
b c d
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
-07, © IAEME
using the Instron 4400 Universal Tester to measure the tensile
used were carried out
a pure PLA , b, c, and d its
. A fixed crosshead rate of 10 mm/min was utilized in all cases
Two metallic grips were attached for griping
Young’s modulus (E) was
cross section area,
known and widely used method to investigate the intermolecular interaction
and phase behavior between the polymers. In this study, the interaction between PLA/SiO2 was
. FTIR spectrum of neat PLA shown
in the region of 3500- 3600 cm-1,
H bending and stretching vibration, C-H asymmetric
respectively, which agree well with the prepared
of PLA/5%SiO2 which
in composites film because

4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 2, February (2014), pp. 01-07, © IAEME
4
a
b
Fig(3):FTIR of a :PLA pure, b : PLA /5%SiO2
2.X-ray Diffraction
X-ray diffrction pattern of polylactic acid shows two peaks located at 2θ= 16°.5 and 19°
with sharp peak for first peak indicating high crystalline structure which agree well with results
reported by Batteazzone et.al [6] as reported of PLA finds that pattern of PLA is characterized by a
broad band with maximum at 2θ = 16.6º, 19.1° . The XRD pattern of composites (PLA/5%SiO2 )
exhibits broad diffraction peak at 2θ = 22ºdue to addition nano SiO2 for silica which agree well with
results reported by A.N. Mohammed et al and find this peak centered at a 2θ = 23◦[7].

5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
6340(Print), ISSN 0976 – 6359(Online)
Fig(4):X-RAY diffraction patterns of
3-Mechanical peoperties
Tensile test provides an indication of the
modulus in eq.2 of the films and find both tensile strength and young modulus increased when add
nano SiO2 which appear in Fig (5) .
biomedical applications. High brittleness
for more applications [8].
Table 1 shows the values of tensile strength of
films using nanosilica enhanced about 35%
properties of prepared nanocomposites were improved by addition of 5 wt.% of silica comparison to
neat PLA matrix, this result agree with ref.[8]
dispersion,the mechanical properties of PLA
and modulus of the composites were enhanced by incorporation of nanoparticles. The silica
nanoparticles were uniformly distributed in the PLA matrix for filler content
whereas some aggregates were detected with further increasing filler
properties of the nano-composites improved because of their degree of dispersion and polymer filler
interaction.
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
6359(Online), Volume 5, Issue 2, February (2014), pp. 01-
5
a
b
diffraction patterns of a :PLA pure, b :PLA /5%SiO
provides an indication of the tensile strength calculated in eq.1
and find both tensile strength and young modulus increased when add
which appear in Fig (5) .PLA is a biodegradable polymer that has been useful in various
High brittleness that are characteristic of PLA must be improved to allow
Table 1 shows the values of tensile strength of pure PLA film prepared and
enhanced about 35% and young modulus enhanced about 25%
properties of prepared nanocomposites were improved by addition of 5 wt.% of silica comparison to
agree with ref.[8] is probably due to achievement of good
the mechanical properties of PLA-silica by melt blending found that the tensile strength
and modulus of the composites were enhanced by incorporation of nanoparticles. The silica
nanoparticles were uniformly distributed in the PLA matrix for filler contents below 5 %·w/w,
whereas some aggregates were detected with further increasing filler concentration .The
composites improved because of their degree of dispersion and polymer filler
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
-07, © IAEME
2θ
2θ
SiO2
calculated in eq.1 and young
and find both tensile strength and young modulus increased when add
that has been useful in various
that are characteristic of PLA must be improved to allow
prepared and its composites
and young modulus enhanced about 25% . Mechanical
properties of prepared nanocomposites were improved by addition of 5 wt.% of silica comparison to
ue to achievement of good
silica by melt blending found that the tensile strength
and modulus of the composites were enhanced by incorporation of nanoparticles. The silica
s below 5 %·w/w,
concentration .The mechanical
composites improved because of their degree of dispersion and polymer filler

6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 2, February (2014), pp. 01-07, © IAEME
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Fig(5):Stress-Strain of PLA and its composites PLA/5%SiO2
Table (1) Mechanical properties of PLA and its composites films
CONCLUSIONS
1- PLAfilm was successfully prepared by casting method.
2- Maximum enhancement in 35%of tensile strength and 25% in young modulus of PLA as
observed by adding 5%nano SiO2, due to their good dispersion in PLA matrix. Obtained results
could be further used for future research in the field of PLA/silica nanocomposites, as
important materials due to their good and satisfying mechanical properties for food packaging
application.
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Sample Tensile
strength(MPa)
Young modulus
(GPa)
PLA 29 2.3
PLA/1%SiO2 32 2.5
PLA/3%SiO2 36 2.9
PLA/5%SiO2 43 3.1
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StressMPa
Strain %
PLA/nano5%SiO2
PLA/nano3%SiO2
PLA/nano1%SiO2
PLA

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