30120140502001

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –

6340(Print), ISSN 0976 – 6359(Online) Volume 5, Issue 2, February (2014), © IAEME

1

EFFECT OF NANO SiO2 ON SOME MECHANICAL PROPERTIES OF

BIODEGRADABLE POLYLACTIC ACID

Nadia Abbas Ali1, Ikram Atta AL-Ajaj

1, Farah Tariq Mohammed Noori

1

1Baghdad 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]

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: www.iaeme.com/ijmet.asp

Journal Impact Factor (2013): 5.7731 (Calculated by GISI)

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IJMET

© I A E M E

International Journal of Mechanical Engineering and Technology (IJMET), ISSN

6340(Print), ISSN 0976 – 6359(Online)

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, m

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 PLANeat PLA film is prepared by weight 2gm of PLA in 20 ml of

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


6359(Online) Volume 5, Issue 2, February (2014), © IAEME

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

reinforcement in composite 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 SiO2particls

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


ed with magnetic bar for 4 h hours at 40°C. After dissolving in


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)


(2014), © 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.

was supplied by Bright China

aldrch Company with

particls

chloroform , PLA films

%) were prepared by solution

in ultrasonic bath for 10


ed with magnetic bar for 4 h hours at 40°C. After dissolving in


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

(Karlsruhe, Germany)



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 o

both ends of the test specimen of the film.

determined according to the following equation

Where: F: force exerted on an object under tension,

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 interaction

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 absorption band

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

a



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 its

. 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 interaction

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

due 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


(2014), © 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, ∆L:

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,

g vibration, C-H asymmetric

, which agree well with the prepared

of PLA/5%SiO2 which

in composites film because



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].



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

whereas some aggregates were detected with further increasing filler

properties of the nano-composites improved because of their degree of dispersion and polym

interaction.



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%


agree with ref.[8] is probably due to achievement of good

echanical properties of PLA-silica by melt blending found that the tensile strength


nanoparticles were uniformly distributed in the PLA matrix for filler contents bel

whereas some aggregates were detected with further increasing filler concentration

composites improved because of their degree of dispersion and polym


(2014), © IAEME

2θ

2θ

SiO2

calculated in eq.1 and young

and find both tensile strength and young modulus increased when add

PLA is a biodegradable polymer that has been useful in various

st be improved to allow

and its composites

and young modulus enhanced about 25% . Mechanical


is probably due to achievement of good

silica by melt blending found that the tensile strength


contents below 5 %·w/w,

concentration .The mechanical

composites improved because of their degree of dispersion and polymer filler



6

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.

REFERENCE

1- P. Qu, Y. Goa, G. F. Wu, and L. P. Zhang, (2010) “Nanocomposite of poly(lactid acid)

reinforced with cellulose nanofibrils”, J .BioResources , vol. 5(3), 1811-1823.

2- B.K. Chen, T.Y. Wu, Y.M. Chang , A. F. Chen ,(2013)” Ductile polylactic acid prepared

with ionic liquids” ,J.Chemical Engineering ,vol. 5 , 215–216.

3- B.H. Li, M.C. Yang,(2006)” Improvement of thermal and mechanical properties of

poly(L-lactic acid) with 4,4-methylene diphenyl diisocyanate”, J. Polym. Adv. Technol.

Vol.17, 439-443.

4- H.S. Mohd , S. Eraricar , I.M. Ida , N.H. Siti ,(2012) “ Cellouse nanofiber isolation and

its fabracication into bio-polymer review “ International Conference on Agricultural and

Food Engineering for Life (Cafei2012) 26-28.

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

0.05.0

10.015.020.025.030.035.040.045.0

0.0 2.0 4.0 6.0 8.0 10.0

Str

ess M

Pa

Strain %

PLA/nano5%SiO2

PLA/nano3%SiO2

PLA/nano1%SiO2

PLA



7

5- J.J.F. Cardoso , Y..C. Queirós, K.J.A. Machado, J.M. Costa , F.E. ucas,(2013) ”

SYNTHESIS, CHARACTERIZATION, AND IN VITRO DEGRADATION OF POLY(LACTIC ACID) UNDER PETROLEUM PRODUCTION CONDITIONS”

BRAZILIAN JOURNAL OF PETROLEUM AND GAS v. 7 n. 2 , 057-069

6- D. Battegazzore, S. Bocchini, A. Frache,(2011)” Crystallization kinetics of poly(lactic

acid)-talc composites” eXPRESS Polymer Letters Vol.5(10),849-85 8.

7- A.N. MOHAMMAD, S. MOHSEN, (2013) “Multi-component reaction on free nano-SiO2

catalyst: Excellent reactivity combined with facile catalyst recovery and recyclability” J.

Chem. Sci. Vol. 125(3) , 537-544.

8- R.M. Izan , A.S. Robert , K. Ing ,(2011) ” Melting Behaviour and Dynamic Mechanical

Properties of Poly(lactic acid)-Hemp-Nanosilica Composites”, Asian Transactions on

Basic and Applied Sciences) ,Vol.3 Issue 2 ,556-561.

9- G .Sanches, R.A.Lopez , J. M. Lagaron ,(2010) “Natural micro and nanobiocomposites

with enchaced and novel functionalities for food biopackaging applications”, J.Trends in

Food Science & Technology,vol. 21, 528-536 .

10- S.Shankar, Dr.H.K.Shivanand and Santhosh Kumar.S, “Experimental Evaluation of

Flexural Properties of Polymer Matrix Composites”, International Journal of Mechanical

Engineering & Technology (IJMET), Volume 3, Issue 3, 2012, pp. 504 - 510, ISSN Print:

0976 – 6340, ISSN Online: 0976 – 6359.

11- Siddhant Datta, B.M. Nagabhushana and R. Harikrishna, “A New Nano-Ceria Reinforced

Epoxy Polymer Composite with Improved Mechanical Properties”, International Journal

of Advanced Research in Engineering & Technology (IJARET), Volume 3, Issue 2, 2012,

pp. 248 - 256, ISSN Print: 0976-6480, ISSN Online: 0976-6499.

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