UNIVERSITI PUTRA MALAYSIA PREPARATION AND CHARACTERIZATION OF POLY(LACTIC ACID)/POLY(BUTYLENE ADIPATE-CO-TEREPTHALATE)/CLAY NANOCOMPOSITES MOHD JUNAEDY BIN OSMAN FS 2011 97
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
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 Chaiman: Faculty: By MOHD JUNAEDY BIN OSMAN February 2011 Nor Azowa bte Ibrahim, PhD 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 ii
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 T g 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. iii
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 iv
after addition of clay influenced the water uptake and biodegradability of PLA/PBAT/OMMT nanocomposites and PLA/PBAT/MMT composites. v
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 Pengerusi: Fakulti: Oleh MOHD JUNAEDY BIN OSMAN Februari 2011 Nor Azowa Bte Ibrahim, PhD 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 vi
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 vii
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 viii
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. ix
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. x
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-coterepththalate) 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: xi
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: xii
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 xiii
TABLE OF CONTENTS ABSTRACT ii ABSTRAK vi ACKNOWLEDGEMENT x APPROVAL DECLARATION TABLE OF CONTENTS LIST OF FIGURES LIST OF TABLES LIST OF SYMBOLS AND ABBREVIATIONS CHAPTER 1 INTRODUCTION 1.1 Background of study 1.2 Research Problems 1.3 Objectives of study 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 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 xi xiii xiv xvii xxi xxii 1 1 3 6 7 7 8 10 11 14 23 26 29 30 34 34 34 36 37 xiv
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 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 72 organoclay 38 38 39 39 39 40 40 40 41 41 42 42 42 43 44 45 45 45 49 52 54 55 56 61 62 65 68 69 xv
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 5 CONCLUSION AND RECOMMENDATIONS 5.1 Conclusion 5.2 Recommendation for future work REFERENCES 125 BIODATA OF STUDENT 139 72 75 78 79 81 85 88 91 94 96 98 99 102 104 106 110 114 117 121 121 124 xvi