YEOH EAN NEE. January 2006

Transcription

1 PREPARATION AND CHARACTERIZATION OF POLY(METHYL METHACRYLATE)/CLAY AND POLY(METHYL ACRYLATE)/CLAY NANOCOMPOSITES BY MICROWAVE IRRADIATION AND CONVENTIONAL HEATING By YEOH EAN NEE Thesis Submitted to the School of Graduate Studies,, in Fulfilment of the Requirements for the Degree of Master of Science January 2006

2 Abstract of thesis presented to the Senate of in fulfilment of the requirement for the degree of Master of Science PREPARATION AND CHARACTERIZATION OF POLY(METHYL METHACRYLATE)/CLAY AND POLY(METHYL ACRYLATE)/CLAY NANOCOMPOSITES BY MICROWAVE IRRADIATION AND CONVENTIONAL HEATING By YEOH EAN NEE January 2006 Chairman: Professor Wan Md. Zin bin Wan Yunus, PhD Faculty : Science Poly(methyl methacrylate)/clay and poly(methyl acrylate)/clay nanocomposites are prepared by polymerizing the monomers in the presence of modified sodium montmorillonite (Na-MMT). Na-MMT is modified by either cetyltrimethylammonium (CTA + ) or dodecylammonium (DDA + ) ions via a cation exchange process. After the modification, CHN elemental analysis shows that CTA + and DDA + ions are present in the montmorillonite. Fourier Transform Infrared (FT-IR) spectra of CTA-MMT and DDA-MMT clearly indicate the presence of new absorption bands, i.e. C-H asymmetric and symmetric stretching vibrations. The basal spacing of CTA-MMT and DDA-MMT increases from 11.6Å to 19.3Å and 18.7Å, respectively. Thermal gravimetric analysis (TGA) shows that CTA-MMT and DDA-MMT degrade at higher temperatures as compared to Na-MMT. Conversions of methyl methacrylate (MMA) and methyl acrylate (MA) into the polymers are carried out by either microwave irradiation or conventional heating methods in the presence of benzoyl peroxide as the initiator. The ii

3 microwave assisted preparation of PMMA/clay and PMA/clay nanocomposites significantly reduces the reaction period as compared to conventional heating. Gel permeation chromatography (GPC) results show that polydispersity indices of PMMAs prepared at high (650 W) and medium high (530 W) microwave power level and PMAs prepared at high microwave power level are narrower than that of PMMA and PMA prepared by conventional heating. FT-IR spectra of PMMA/clay and PMA/clay clearly indicate the presence of the polymer and clay functional groups. X-ray diffraction analysis (XRD) analysis shows that there are increments in the clay basal spacing of the PMMA/clay and PMA/clay nanocomposites prepared by both methods. This indicates that PMMA or PMA are successfully intercalated into the interlayer galleries of the clay. However, transmission electron microscopy (TEM) shows that the nanocomposites are of intercalated and flocculated type. The TGA thermograms indicate enhancement in thermal stability for PMMA/clay and PMA/clay nanocomposites and microcomposites as compared to that of the pure PMMA or PMA prepared by both microwave irradiation and conventional heating. The remarkable improvement in storage modulus of PMMA/clay and PMA/clay nanocomposites compared to that of the pure PMMA and PMA indicates there is a strong interaction between the matrix and the organoclay. The glass transition temperatures (T g ) of PMMA/CTA-MMT nanocomposites increase by around o C as compared to that of the pure PMMA. PMMA/DDA-MMT nanocomposite with 1 wt% of DDA-MMT filled PMMA gives a higher T g compared to the other DDA-MMT filled PMMA. However, the T g for PMA/CTA-MMT and PMA/DDA-MMT nanocomposites is similar to that of the pure PMA. iii

4 Abstrak tesis yang dikemukakan kepada Senat sebagai memenuhi keperluan untuk ijazah Master Sains PENYEDIAAN DAN PENCIRIAN NANOKOMPOSIT POLI(METIL METAKRILAT)/TANAH LIAT DAN POLI(METIL AKRILAT)/TANAH LIAT MELALUI PENYINARAN GELOMBANG MIKRO DAN PEMANASAN KONVENSIONAL Oleh YEOH EAN NEE Januari 2006 Pengerusi Fakulti : Professor Wan Md. Zin bin Wan Yunus, PhD : Sains Nanokomposit poli(metil metakrilat)/tanah liat dan poli(metil akrilat)/tanah liat disediakan melalui pempolimeran monomernya dengan kehadiran natrium montmorillonit (Na-MMT) yang terubahsuai. Na-MMT diubahsuai dengan menggunakan ion setiltrimetilammonium (CTA + ) dan ion dodesilammonium (DDA + ) melalui proses penukaran kation. Analisis unsur CHN yang dilakukan selepas pengubahsuaian menunjukkan bahawa ion-ion CTA + dan DDA + hadir dalam montmorillonit tersebut. Spektra infra-merah terubah Fourier (FT-IR) bagi CTA-MMT dan DDA-MMT jelas menunjukkan kehadiran jalur serapan baru, iaitu getaran regangan asimetrik dan simetrik C-H. Ruang jarak antara lapisan dalam CTA-MMT dan DDA- MMT meningkat daripada 11.6Å ke 19.3Å dan 18.7Å. Analisis termogravimetrik (TGA) menunjukkan bahawa CTA-MMT dan DDA-MMT diurai pada suhu yang lebih tinggi berbanding dengan Na-MMT. Penukaran metil metakrilat (MMA) dan metil akrilat (MA) kepada polimer masing-masing dilakukan melalui kaedah penyinaran gelombang iv

5 mikro atau pemanasan konvensional dengan kehadiran benzoil peroksida sebagai pemula. Jangka masa penyediaan nanokomposit PMMA/tanah liat dan PMA/tanah liat melalui penyinaran gelombang mikro adalah pendek berbanding dengan penyediaan melalui pemanasan konvensional. Keputusan kromatografi penelapan jel (GPC) menunjukkan bahawa indeks poliserakan bagi PMMA yang disediakan pada tahap gelombang mikro kuasa tinggi (650W) dan sederhana tinggi (530W) dan PMA yang disediakan pada tahap gelombang mikro kuasa tinggi adalah lebih sempit berbanding dengan penyediaan melalui kaedah pemanasan konvensional. Spektra FT-IR nanokomposit PMMA/tanah liat dan PMA/tanah liat jelas menunjukkan kehadiran kumpulan-kumpulan berfungsi polimer dan tanah liat. Analisis pembelauan sinaran-x (XRD) menunjukkan bahawa terdapat peningkatan ruang jarak antara lapisan nanokomposit PMMA/tanah liat dan PMA/tanah liat yang disediakan melalui keduadua kaedah. Ini menunjukkan bahawa PMMA atau PMA telah berjaya diinterkalasi ke dalam galeri ruang antara lapisan tanah liat. Walau bagaimanapun, mikroskopi elektron penghantaran (TEM) menunjukkan bahawa nanokomposit yang dihasilkan adalah jenis interkalasi dan penggumpalan. Termogram TGA menunjukkan peningkatan kestabilan terma bagi nanokomposit dan mikrokomposit PMMA/tanah liat dan PMA/ tanah liat berbanding dengan PMMA atau PMA tulen yang disediakan melalui kedua-dua kaedah. Peningkatan modulus bagi nanokomposit PMMA/tanah liat dan PMA/tanah liat berbanding dengan PMMA dan PMA tulen menunjukkan interaksi yang kuat antara matriks dengan tanah liat. Suhu peralihan kaca (T g ) bagi nanokomposit PMMA/CTA- MMT meningkat sebanyak o C berbanding dengan PMMA tulen. T g bagi PMMA/DDA-MMT di mana 1 wt% DDA-MMT terisi dalam PMMA adalah lebih v

6 tinggi berbanding dengan PMMA yang diisi dengan kandungan DDA-MMT yang berlainan. Walau bagaimanapun, T g bagi nanokomposit PMA/tanah liat adalah hampir sama dengan PMA tulen. vi

7 ACKNOWLEDGEMENTS I would like to express my appreciation to all of the individuals who contributed to this project, in particular, the chairman of my Supervisory Committee, Professor Dr. Wan Md. Zin bin Wan Yunus, for his guidance, constructive comments, continuous support and advice throughout the duration of this study. I extend my sincere thank to my cosupervisors, Professor Dr. Kaida Khalid and Associate Professor Dr. Mohammad Zaki Abd. Rahman for their supervision, support and suggestions. I also wish to express my appreciation to all the staff in Electron Microscopy Unit, UPM especially Mr. Ho Oi Kuan. Sincere thanks are also extended to all the Laboratory Assistants in the Chemistry Department UPM especially Mr. Zulhisham, Mrs Ros, Mr. Kamal and Mr. Ismail as well as Miss Wan Yusmawati bt Wan Yussof in the Physics Department UPM for their dedication in delivering technical assistance and contribution towards these departments. My appreciation is further extended to Mr Yussof and Mr. Mohamad Nor in the Chemistry and Food Technology Department UKM for delivering technical assistance. My special appreciation also goes to all my senior and junior lab mates in Lab 407 and 255 for their endless support and also providing me with laughter, joy and friendship all the way through. Last but not least, my deepest affection and gratitude goes to my beloved family members for their continuous understanding and moral support throughout the period of study. Special thanks to Ministry of Science, Technology and Environment for the financial support under the IRPA grant. vii

8 I certify that an Examination Committee met on 26 January 2006 to conduct the final examination of Yeoh Ean Nee on his Master of Science thesis entitled Preparation and Characterization of Poly(methyl methacrylate)/clay and Poly(methyl acrylate)/clay Nanocomposites by Microwave Irradiation and Conventional Heating in accordance with Universiti Pertanian (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (higher Degree) Regulation The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows: Mohd Zobir Hussein, PhD Professor Faculty of Science (Chairman) Mansor Ahmad, PhD Associate Professor Faculty of Science (Internal Examiner) Zainal Abidin Talib, PhD Associate Professor Faculty of Science (Internal Examiner) Jamil Ismail, PhD Professor School of Chemical Science Universiti Sains Malaysia (External Examiner) HASANAH MOHD. GHAZALI, PhD Professor/Deputy Dean School of Graduate Studies Date: 27 March 2006 viii

9 This thesis submitted to the Senate of and has been accepted as fulfilment of the requirement for the degree of Master of Science. The members of the Supervisory Committee are as follows: Wan Md. Zin bin Wan Yunus, PhD Professor Faculty of Science (Chairman) Kaida Khalid, PhD Professor Faculty of Science (Member) Mohammad Zaki Abdul Rahman, PhD Associate Professor Faculty of Science (Member) AINI IDERIS, PhD Professor/Dean School of Graduate Studies Date: ix

10 DECLARATION I hereby declare that the thesis is based on my original work except for the citations which have been duly acknowledged. I also declare that is has not been previously or concurrently submitted for any other degree at UPM. YEOH EAN NEE Date: 10 March 2006 x

11 TABLE OF CONTENTS Page ABSTRACT ABSTRAK ACKNOWLEDGEMENT APPROVAL DECLARATION LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS ii iv vii viii x xiii xv xxv CHAPTER I INTRODUCTION 1 General Background Background of the Study Scope of the Study Objectives II LITERATURE REVIEW 5 Acrylic Thermoplastic: Poly(methyl methacrylate) and Poly(methyl 5 acrylate) Properties of poly(methyl methacrylate)and poly(methyl acrylate) Methyl methacrylate and methyl acrylate monomer Application of PMMA and PMA Polymerization Mechanism of radical chain polymerization Steady-state kinetics of radical chain polymerization: over-all rate as a function of conversion Montmorillonite Clay 16 Montmorillonite characteristics 18 Modification of montmorillonite 19 Nanocomposites 25 Structures of polymer/clay nanocomposites 27 Preparation of polymer/clay nanocomposites 29 Properties of polymer/clay nanocomposites 35 Polymer/clay nanocomposites 42 Microwave Irradiation Dielectric polarization Two principal mechanisms for interaction with material Microwave assisted of polymerization xi

12 III MATERIALS AND METHODS Materials Methods Preparation of Organoclay Preparation of PMMA/clay and PMA/clay Nanocomposites Microwave irradiation Conventional heating Calibration of domestic microwave oven Characterization of Organoclay, PMMA, PMA, PMMA/clay and PMA/clay Nanocomposites Fourier transform infrared analysis CHN elemental analysis X- ray diffraction analysis Thermal gravimetric analysis Dynamic mechanical analysis Gel permeation chromatography Energy filter transmission electron microscopy Calculation of theoretical number-average molecular weight (M n th ) Calculation of poly-dispersity index (PDI) Calculation of degree of polymerization (n) IV RESULTS AND DISCUSSION: Preparation and Characterization of Organoclay Amount of intercalation agent in the interlayer spacing of Na- MMT FT-IR analysis of organoclay XRD analysis of organoclay TGA of organoclay Preparation of PMMA, PMA, PMMA/Clay and PMA/Clay Nanocomposites Preparation of PMMA and PMA by Microwave Irradiation Method Effect of high power and medium high power level of microwave irradiation on various ratios of MMA: BPO and MA: BPO Preparation of PMMA and PMA by Conventional Heating Method Effect of reaction parameters on the percentage of conversion of MMA and MA Preparation of PMMA/clay and PMA/clay Nanocomposite by Microwave Irradiation Method Effect of high power and medium high power level of microwave irradiation on various ratios of MMA: BPO: CTA-MMT and MA: BPO: CTA-MMT Effect of high power and medium high power level of microwave irradiation on various ratios of MMA: BPO: DDA-MMT and MA: BPO: DDA-MMT xii

13 Preparation of PMMA/clay and PMA/clay Nanocomposite by Conventional Heating Method Effect of reaction parameters on the percentage of conversion of MMA/CTA-MMT and MA/CTA-MMT nanocomposites Effect of reaction parameters on the percentage of conversion on MMA/DDA-MMT and MA/DDA-MMT nanocomposites Effect of reaction parameters on the percentage of conversion on MMA/Na-MMT and MA/Na-MMT microcomposites Comparison of Microwave Irradiation with Conventional Heating on Polymerization Period Characterization Characterization of PMMA and PMA FT-IR analysis of PMMA and PMA Molecular weight studies by gel permeation chromatography Thermal properties of PMMA and PMA prepared by microwave irradiation and conventional heating method Characterization of PMMA/clay and PMA/clay Nanocmposites FT-IR analysis of PMMA/clay and PMA/clay nanocomposites XRD studies Thermal gravimetric analysis of PMMA/clay and PMA/clay nanocomposites Dynamic mechanical analysis Analysis of clay dispersion of PMMA/clay and PMA/clay Effect of clay content on the thermal gravimetric analysis of PMMA/clay and PMA/clay nanocomposites Effect of organoclay content on the storage modulus of PMMA/clay and PMA/clay nanocomposites Effect of organoclay content on the glass transition temperature of PMMA/clay and PMA/clay nanocomposites V CONCLUSIONS Recommemdation for Further Studies REFERENCES 213 APPENDICES 225 BIODATA OF THE AUTHOR 231 xiii