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UNIVERSITI PUTRA MALAYSIA
PREPARATION AND CHARACTERIZATION OF POLY(LACTIC
ACID)/POLY(BUTYLENE ADIPATE-CO-TEREPTHALATE)/CLAY
NANOCOMPOSITES
MOHD JUNAEDY BIN OSMAN
FS 2011 97
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PREPARATION AND CHARACTERIZATION OF POLY(LACTIC
ACID)/POLY(BUTYLENE ADIPATE-CO-TEREPTHALATE)/CLAY
NANOCOMPOSITES
By
MOHD JUNAEDY BIN OSMAN
Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia,
in Fulfillment of the Requirements for Degree of Master of Sciences
February 2011
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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in
fulfilment of requirements for the Degree Master of Science
PREPARATION AND CHARACTERIZATION OF POLY(LACTIC
ACID)/POLY(BUTYLENE ADIPATE-CO-TEREPTHALATE)/CLAY
NANOCOMPOSITES
By
MOHD JUNAEDY BIN OSMAN
February 2011
Chaiman: Nor Azowa bte Ibrahim, PhD
Faculty: Science
Poly(lactic acid) (PLA) is a biodegradable plastic that is brittle. Because of this
nature, PLA has a limitation in its usage. The toughness of PLA can be improved
by adding plasticizer. In this study, poly(butylenes adipate-co-terepthalate) was
added to act as a plasticizer for PLA. The new biodegradable plastic, poly(lactic
acid)/poly(butylene adipate-co-terepththalate) (PLA/PBAT), PLA/PBAT/sodium
montmorillonite (PLA/PBAT/Na-MMT) and PLA/PBAT/organomodified
montmorillonite (PLA/PBAT/OMMT) nanocomposites were prepared by using
melt blending technique. This thesis describes the preparation and
characterization of PLA/PBAT blends, PLA/PBAT/MMT composites and
PLA/PBAT/OMMT nanocomposites.
In order to improve the compatibility of polymer and clay, the clay was first
modified to become organoclay (OMMT). The organoclays were prepared from
sodium montmorillonite (Na-MMT) through cation exchange technique using
two types of organic surfactants; octadecyl amine (ODA) and dimethyl
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dioctadecyl amine bromide (DDOAB). Cloisite 20A (C 20A) commercialize
organoclay also used to compare the effect of this organoclay to PLA/PBAT
blends. The increase in interlayer spacing of OMMT was characterized using X-
Ray Diffraction (XRD) analysis. The presence of alkylammonium ions in
organoclay was also studied by Fourier Transform Infrared (FTIR). Thermal
behaviour and amount of surfactant intercalate into the clay galleries of OMMT
was study by Thermogravimetric analysis (TGA) and elemental analysis
respectively.
In studying properties of PLA/PBAT blends, the interaction between these two
polymers will affect the tensile and mechanical properties of PLA/PBAT blends.
In this study, PBAT acts as a plasticizer of PLA whereas the addition of PBAT
decreased the tensile strength and tensile modulus of PLA however increased the
elongation at break. The interaction between PLA and PBAT was examined by
FTIR. From the dynamic mechanical analysis, PLA and PBAT form immiscible
blends as there is two peaks at loss modulus curve represented the Tg for PLA
and PBAT. This was supported by SEM observation. Water absorption of sample
was found have the same trends as the biodegradation rate of the sample. With
greater amounts of PBAT, water absorption and biodegradation rate of the
sample increase.
Since blending PLA and PBAT will result immiscible blends, OMMT is
introduce into PLA/PBAT blends system to improve the compatibility between
PLA/PBAT and OMMT. The type of modifier plays a significant role to
influence the tensile properties of PLA/PBAT/OMMT nanocomposites.
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Generally, OMMT with more polar modifier give higher tensile properties of
PLA/PBAT/OMMT nanocomposites. This was expected due to the hydrogen
bonding between PLA/PBAT blends and the hydroxyl group inside the clay
galleries. As a result, shifting for C - O group detected on FTIR spectra.
Dynamic mechanical studies revealed the same result as the tensile properties.
The addition of OMMT into PLA/PBAT blends increased the thermal
degradation as shown in TGA. SEM images show the improvement on continuity
and compatibility of PLA/PBAT/OMMT nanocomposites as the reduction of
cavity and smoother surface. Transmission electron microscopy (TEM) was used
to observe the distribution of OMMT and study the type of nanocomposite
formed. The addition of OMMT also enhances the barrier properties in term of
water absorption of PLA/PBAT/OMMT nanocomposites, which due to
increasing of tortousity. The sample was confirmed as biodegradable as it
degraded (loss in weight) after 3 weeks of biodegradable test.
The effect of clay loading on tensile properties, mechanical properties, thermal
properties, water uptake and biodegradability of PLA/PBAT blends,
PLA/PBAT/MMT composites and PLA/PBAT/OMMT nanocomposites were
discuss in term of clay loading. The optimum clay loading for PLA/PBAT blends
is 1%. The tensile strength and tensile modulus increase until 1 % clay loading
and start to decrease with increasing clay loading due to the tactoid structure at
high clay loading. The mechanical properties and thermal properties increased
with increasing clay content due to the enhancement reinforcing action between
clay and polymer and the barrier properties of the clay. The tortuous path created
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after addition of clay influenced the water uptake and biodegradability of
PLA/PBAT/OMMT nanocomposites and PLA/PBAT/MMT composites.
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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai
memenuhi keperluan untuk Ijazah Master Sains.
PENYEDIAAN DAN PENCIRIAN NANOKOMPOSIT POLI(ASID
LAKTIK)/POLI(BUTILENA ADIPAT-KO-TEREFTALAT)/TANAH LIAT
Oleh
MOHD JUNAEDY BIN OSMAN
Februari 2011
Pengerusi: Nor Azowa Bte Ibrahim, PhD
Fakulti: Sains
Poli(asid laktik) (PLA) adalah salah satu plastik terbiodegradasi yang rapuh.
Disebabkan sifat ini, PLA penggunaannya terbatas. Kekerasan PLA boleh
ditambahbaikkan dengan menambahkan pemplastik. Dalam kajian ini,
poli(butilena adipat-ko-tereftalat) (PBAT) telah ditambah untuk bertindak
sebagai pemplastik bagi PLA. Plastik terbiodegradasi baru, Poli(asid
laktik)/poli(butilena adipat-ko-tereftalat) (PLA/PBAT), PLA/PBAT/natrium
montmorillonit (PLA/PBAT/Na-MMT) dan PLA/PBAT/organik terubahsuai
montmorillonit (PLA/PBAT/OMMT) telah disediakan menggunakan teknik
pengadunan lebur. Tesis ini menghuraikan tentang penyediaan dan pencirian
adunan PLA/PBAT, PLA/PBAT/Na-MMT komposit dan PLA/PBAT/OMMT
nanokomposit.
Untuk menambahbaikkan keserasian polimer dan tanah liat, tanah liat telah
diubahsuai menjadi organo-tanah liat (OMMT). Organo-tanah liat telah
disediakan dari natrium montmorillonit (Na-MMT) melalui teknik pertukaran
kation menggunakan dua jenis surfaktan organik; oktadesil amino (ODA) dan
dimetil dioktadesil amino bromida (DDOA). Cloisit 20A (C 20A) organo-tanah
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liat komersil juga digunakan untuk membandingkan kesan organo-tanah liat ini
kepada adunan PLA/PBAT. Penambahan pada jarak antara lapisan OMMT telah
ditentukan menggunakan analisis belauan sinar X (XRD). Kehadiran ion
alkilammonium dalam organo-tanah liat telah ditentukan menggunakan
spektroskopi infra-merah pengubah Fourier (FTIR). Kelakuan terma dan jumlah
surfaktan yang masuk ke dalam lapisan tanah liat OMMT ditentukan
menggunakan analisis termogravimetri (TGA) dan analisis unsur.
Dalam mempelajari sifat-sifat adunan PLA/PBAT, interaksi antara kedua-dua
polimer ini dipercayai mempengaruhi regangan dan sifat-sifat mekanikal adunan
PLA/PBAT. PBAT telah diketahui bertindak sebagai pemplastik kepada PLA
dimana penambahan PBAT, menurunkan kekuatan regangan dan modulus
regangan PLA namun meningkatkan nilai pemanjangan putus. Interaksi antara
PLA dan PBAT telah disiasat menggunakan FTIR. Dari analisis mekanikal
dinamik, PLA dan PBAT membentuk adunan tidak berpadu kerana wujud dua
puncak pada modulus hilang mewakili Tg untuk PLA dan PBAT. Ini disokong
dengan pemerhatian SEM. Penyerapan air oleh sampel ditemui mempunyai
kecenderungan yang sama dengan kadar biodegradasi sampel. Dengan
penambahan jumlah PBAT, penyerapan air dan kadar biodegradasi sampel juga
bertambah.
Oleh kerana mengadun PLA dan PBAT akan menghasilkan adunan tidak
berpadu, OMMT diperkenalkan ke dalam adunan PLA/PBAT untuk
menambahbaikkan keserasian antara PLA/PBAT dan OMMT. Jenis
pengubahsuai memainkan peranan yang penting dalam mempengaruhi sifat
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regangan PLA/PBAT/OMMT nanokomposit. Amnya OMMT dengan
pengubahsuai yang lebih polar menghasilkan PLA/PBAT/OMMT nanokomposit
bersifat regangan tinggi. Ini sudah dijangka kerana ikatan hidrogen antara adunan
PLA/PBAT dan kumpulan hidroksil di dalam lapisan tanah liat. Ini disahkan
dengan penganjakkan untuk kumpulan C - O dikesan pada spektra FTIR. Kajian
mekanikal dinamik membuktikan keputusan yang sama dengan keputusan sifat
regangan. Penambahan OMMT ke dalam adunan PLA/PBAT meningkatkan
degradasi termal seperti yang ditunjukkan dalam TGA. Imej SEM menunjukkan
penambahbaikkan dalam kesinambungan dan keserasian PLA/PBAT/OMMT
nanokomposit dari pengurangan jumlah lubang dan permukaan yang rata.
Mikroskop transmisi elektron (TEM) digunakan bagi memerhatikan pengagihan
OMMT dan mengkaji jenis nanokomposit terhasil. Penambahan OMMT juga
meningkatkan sifat rintangan dari sudut penyerapan air PLA/PBAT/OMMT
nanokomposit adalah kerana peningkatan keluk-keluk dalam polimer. Sampel
disahkan terdegradasi kerana terdapat penyusutan berat selepas 3 minggu dalam
ujian terbiodegradasi.
Kesan pengisian tanah liat terhadap sifat regangan, sifat mekanikal, sifat terma,
pengambilan air dan sifat biodegradasi adunan PLA/PBAT, PLA/PBAT/MMT
komposit dan PLA/PBAT/OMMT nanokomposit dibincangkan dari sudut jumlah
pengisian tanah liat. Pengisian tanah liat yang optimum untuk adunan
PLA/PBAT adalah 1%. Kekuatan regangan dan modulus regangan bertambah
sehingga 1% kandungan tanah liat dan mula berkurang dengan penambahan
kandungan tanah liat kerana struktur taktoid dalam kandungan tanah liat yang
tinggi. Sifat mekanikal dan sifat termal meningkat dengan penambahan tanah liat
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termuat disebabkan peningkatan kesan peneguhan antara tanah liat dan polimer
juga sifat rintangan tanah liat. Laluan berkelok-kelok terhasil setelah
penambahan tanah liat mempengaruhi pengambilan air dan biodegradasi
PLA/PBAT/OMMT nanokomposit dan PLA/PBAT/MMT komposit.
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ACKNOWLEDGEMENTS
Alhamdulillah, praise to Allah the Almighty for his blessing this study was
completely carried out. First and foremost I would like to express my profound
and most sincere gratitude to Dr Nor Azowa Bte Ibrahim chairman of the
supervisory committee and other member of the committee, Prof Dato Dr Wan
Md Zain Bin Wan Yunus and Dr Jamaliah Bte Sharif for their guidance,
suggestion and continuous encouragement throughout the course of this research.
I would like to acknowledge the technical staff of chemistry department, UPM
for their help in getting the TGA, CHNS, FTIR, the Bioscience Institute, UPM
for their help in getting SEM and TEM micrographs and polymer unit of Nuclear
Agency for their help in getting DMA results.
I am thankful to all my friends’ expecially Mohd Nazri Mohd Rahim, Mohd
Lokman Che Jusoh, Mohd Izwan Lazim, Mohd Fazlin Nazli, Mohd
Khairulneeza, Chieng Buong Wei, Nurazlin Amrullah, and Then Yoon Yee for
their help and advice in completing this research.
I also grateful to the UPM for giving me GRF to support my life during two
years in master course. Finally, I would like to extend my sincere gratitude to my
beloved family because of constant morale support and inspiration.
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APPROVAL
I certify that an Examination committee has met on 17 February 2011 to conduct
the final examination of Mohd Junaedy Bin Osman on his degree thesis entitled
“Preparation and characterization of poly(lactic acid)/poly(butylenes adipate-co-
terepththalate) clay nanocomposites” in accordance with Universiti Pertanian
Malaysia (Higher Degree) Act 1980 and University Pertanian Malaysia (Higher
Degree) Regulation 1981. The committee recommended that the student awarded
the degree of Master of Science.
Member of the Examination Committee were as follows:
Mansor Ahmad, PhD
Associate Professor
Faculty of Science
Universiti Putra Malaysia
(Chairman)
Mohamad Zaki Ab. Rahman, PhD
Associate Professor
Faculty of Science
Universiti Putra Malaysia
(Internal Examiner)
Sidik Silong, PhD
Associate Professor
Faculty of Science
Universiti Putra Malaysia
(Internal Examiner)
Ishak Ahmad, PhD
Associate Professor
School Of Chemical and Food Technology
Faculty of Science and Technology
Universiti Kebangsaan Malaysia
43600, Bangi, Selangor
Malaysia.
(External Examiner)
________________________
Shamsuddin Sulaiman, PhD
Professor and Deputy Dean
School of Graduate Studies
Universiti Putra Malaysia
Date:
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This thesis was submitted to the Senate of Universiti Putra Malaysia and has
been accepted as fulfillment of the requirement for the Master of Science. The
members of the Supervisory Committee were as below:
Nor Azowa Ibrahim, PhD
Associate Professor
Faculty of Science
University Putra Malaysia
(Chaiman)
Dato’ Wan Md Zin Wan Yunus, PhD
Professor
Faculty of Science
Universiti Putra Malaysia
(Member)
Jamaliah Sharif, PhD
Polymer Department
Malaysian Nuclear Agency
Bangi, 43000 Kajang
Selangor,
Malaysia
_______________________________
HASANAH MOHD GHAZALI, PhD
Professor and Dean
School of Graduate Studies
Universiti Putra Malaysia
Date:
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DECLARATION
I declare that the thesis is my original work except for quotation and citation,
which have been duly acknowledged. I also declare that this thesis has not been
previously and is not concurrently submitted for any other degree at Universiti
Putra Malaysia or any other institution.
_____________________________
MOHD JUNAEDY BIN OSMAN
Date: 17 February 2011
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TABLE OF CONTENTS
ABSTRACT ii
ABSTRAK vi
ACKNOWLEDGEMENT x
APPROVAL
DECLARATION
TABLE OF CONTENTS
xi
xiii
xiv
LIST OF FIGURES xvii
LIST OF TABLES xxi
LIST OF SYMBOLS AND ABBREVIATIONS xxii
CHAPTER
1 INTRODUCTION
1.1 Background of study
1.2 Research Problems
1.3 Objectives of study
1
1
3
6
2 LITERATURE REVIEW
2.1 Biodegradable Plastic
2.1.1 Poly(lactic acid) (PLA)
2.1.2 Poly(butylenes adipate-co-terepththalate)
(PBAT)
2.2 Polymer blends
2.3 Problems in polymer blends
2.4 Ways to improve miscibility of the blends
2.5 Clay modification
2.6 Preparation of nanocomposite
2.7 Properties of nanocomposites
7
7
8
10
11
14
23
26
29
30
3 MATERIALS AND METHODS
3.1 Materials
3.2 Preparation of organoclay
3.3 Preparation of PLA/PBAT blends
3.4 Preparations of PLA/PBAT Nanocomposites
34
34
34
36
37
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3.5 Characterization of organoclay
3.5.1 X-Ray Diffraction study
3.5.2 Fourier Transform Infrared spectroscopy
(FTIR) study
3.5.3 Thermogravimetric Analysis
3.5.4 Elemental Analysis
3.6 Characterization of PLA/PBAT and PLA/PBAT
nanocomposites
3.6.1 X-Ray Diffraction Study
3.6.2 Tensile Properties study
3.6.3 Fourier Transform Infrared spectroscopy
3.6.4 Dynamic Mechanical Analysis
3.6.5 Thermogravimetric Analysis
3.6.6 Scanning Electron Microscopy
3.6.7 Transmission Electron Microscopy
3.6.8 Water Adsorption Test
3.6.9 Biodegradable Test
38
38
39
39
39
40
40
40
41
41
42
42
42
43
44
4 RESULTS AND DISCUSSIONS
4.1 Preparation and characterization of organoclay
4.1.1 Interlayer spacing of Organoclay (XRD)
4.1.2 FTIR analysis
4.1.3 Thermogravimetric analysis
4.1.4 Elemental analysis
4.2 Preparation of PLA/PBAT blends
4.2.1 Tensile Properties
4.2.2 FTIR analysis
4.2.3 Dynamic Mechanical Analysis
4.2.4 Morphology characterization
4.2.5 Water absorption test
4.2.6 Biodegradability test
4.3 Characterization of nanocomposites: Effect of type of
organoclay
45
45
45
49
52
54
55
56
61
62
65
68
69
72
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4.3.1 XRD analysis
4.3.2 FTIR analysis
4.3.3 Tensile strength
4.3.4 Tensile modulus
4.3.5 Dynamic Mechanical properties
4.3.6 Thermogravimetric analysis
4.3.7 Surface morphology
4.3.8 TEM analysis
4.3.9 Water Adsorption Test
4.3.10 Biodegradability Test
4.4 Characterization of PLA/PBAT nanocomposites: Effect
of clay loading
4.4.1 XRD analysis of PLA/PBAT nanocomposites
4.4.2 Tensile strength
4.4.3 Tensile modulus
4.4.4 Dynamic Mechanical properties
4.4.5 Thermogravimetric analysis
4.4.6 Water absorption test
4.4.7 Biodegradability test
72
75
78
79
81
85
88
91
94
96
98
99
102
104
106
110
114
117
5 CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion
5.2 Recommendation for future work
121
121
124
REFERENCES 125
BIODATA OF STUDENT 139
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