Influence Of Suspension Preparation Condition And Medium Microstructure And Phase Of Electrophoretic Deposited Poly (Vinylidene Fluoride) Films.

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UNIVERSITI TEKNIKAL MALAYSIA MELAKA

INFLUENCE OF SUSPENSION PREPARATION CONDITION

AND MEDIUM MICROSTRUCTURE AND PHASE OF

ELECTROPHORETIC DEPOSITED POLY(VINYLIDENE

FLUORIDE) FILMS

This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering

(Engineering Materials) (Hons.)

NURSYAFIKA BINTI ROHIZAT B051110355

901130-01-6122

FACULTY OF MANUFACTURING ENGINEERING 2015

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ABSTRAK

Tesis ini mengenai pencirian PVDF (Polyvinylidene Fluorida) filem aplikasi piezoelektrik untuk menyelesaikan masalah retak kerana ikatan yang lemah antara zarah PVDF yang didepositkan. Objektif eksperimen ini untuk mencirikan penggantungan dan filem PVDF yang disediakan oleh pelarut polimer berbeza (MEK (Methyl Ethyl Ketone) dan DMF (Dimethyl Formamide)), suhu kacau dan masa. Kaedah yang digunakan untuk deposit zarah PVDF pada ITO kaca ialah pemendapan elektroforetik. Ujian pemendapan menunjukkan PVDF yang disediakan dalam penggantungan DMF mempunyai kestabilan tinggi berbanding sampel MEK. Kekasaran permukaan rendah telah ditunjukkan oleh UV-vis Spectra dan SEM dalam filem PVDF yang disediakan menggunakan penggantungan DMF. Filem PVDF yang disediakan menggunakan penggantungan MEK mempunyai filem permukaan yang sangat kasar dan tidak rata berbanding DMF sampel. Filem PVDF yang disediakan menggunakan penggantungan DMF (120˚C, 8 jam) mempunyai permukaan rata dan lebih rendah, walaupun tidak menyeliputi keseluruh kawasan filem. Analisis EDS pada sampel 120˚C, 2 jam dan 120˚C, 8 jam keadaan kacau yang disediakan menggunakan penggantungan DMF menunjukkan kawasan liputan filem PVDF ialah 60.4% bagi 120˚C, 8 jam sampel. Keputusan FTIR menunjukkan filem PVDF yang disediakan menggunakan penggantungan DMF mengandungi β-fasa sahaja, manakala di MEK mengandungi α dan β-fasa. Oleh itu, parameter terbaik filem adalah pada 120˚C, 8 jam yang disediakan menggunakan penggantungan DMF kerana ia mempunyai permukaan filem paling rata berbanding dengan sampel yang lain.

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ABSTRACT

This thesis is about the characterization of PVDF (Polyvinylidene Fluoride) film of piezoelectric applications in order to solve the crack problem due to weak bonding between deposited PVDF particles. The objective of this experiment is to characterize PVDF suspensions and PVDF films prepared by different polymer solvents (MEK (Methyl Ethyl Ketone) and DMF (Dimethyl Formamide)), stirring temperatures and time. The method used to deposit the PVDF particles on the ITO glass is electrophoretic deposition. Sedimentation test shows PVDF prepared in DMF based suspension have higher stability when compared with MEK sample. Low surface roughness was shown by UV-vis Spectra and SEM in PVDF films prepared using DMF based suspension. PVDF films prepared using MEK based suspension have a very rough and uneven surface films as compared to DMF derived sample. PVDF film prepared in DMF based suspension (at 120˚C, 8 hr stirring condition) has even and low surface roughness, although did not have fully coverage film area. EDS analysis is used in 120˚C, 2 hr and 120˚C, 8 hr stirring condition that prepared in DMF based suspension show PVDF film coverage area is 60.4% for for 120˚C, 8 hr sample. FTIR results show PVDF films prepared in DMF based suspension contain β-phase alone, while in MEK contain α and β-phase. Therefore, the best parameter of PVDF film is at 120˚C, 8 hr stirring condition prepared in DMF based suspension because it has the most even films’ surface compared to other samples.

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iii

DEDICATION

I dedicate this report to my frist and second supervisor, Dr. Muhammad Zaimi bin Zainal Abidin and Dr. Lau Kok Tee, thank you for being a guider during this final year project. Thank you for your cooperation and help in the success of this report. Thanks also to my parents for being a pillar of strength for me when I was weak and also to my friends, thank you for not throwing me away when I disappoint you. Thank you for loving me.

Finally, I dedicate this report to my examiners, Associate Prof. Dr. Zulkifli bin Mohd Rosli and Dr. Zurina binti Shamsudin for being my correctors, and also like to dedicate this report to all my respectable lecturers.

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ACKNOWLEDGEMENT

First of all, I am grateful to God for the opportunity to prepare this final year project report. Special appreciation to my first supervisor, Dr. Muhammad Zaimi bin Zainal Abidin for his supervision and constant support. His invaluable help of constructive comments and suggestions throughout the report. Not forgotten, my appreciation to my second supervisor, Dr. Lau Kok Tee for his support and knowledge regarding this topic.

I would like to thank to all the assistance engineers that assist in identifying equipment that will be used in the laboratory and I am indebted to my final year project examiners, Associate Prof. Dr. Zulkifli bin Mohd Rosli and Dr. Zurina binti Shamsudin for being my correctors. Therefore, I consider myself as a very lucky individual as I was provided with an opportunity to be a part of this project. I am also grateful for having a chance to meet so many wonderful people and professionals who lead me through this final year project.

Thanks also to my colleagues that have same field as me, thanks for the support, friendship and memories. Last but not least, my deepest gratitude goes to my beloved parents for their endless love, prayers and encouragement. To those who indirectly contributed in this research, your kindness means a lot to me. Thank you very much.

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Abstrak i

Abstract ii

Dedication iii

Acknowledgement iv

Table of Contents viii

List of Tables ix

List of Figures viii

List Abbreviations, Symbols And Nomenclatures xii

CHAPTER 1: INTRODUCTION

1.0 Introduction 1

1.1 History and Background 2

1.2 Problem Statement 6

1.3 Objectives 7

1.4 Scope 7

CHAPTER 2: LITERATURE REVIEW

2.0 Introduction 8

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2.2 Deposition of PVDF 12

2.3 Definition of Agglomeration 14

2.3.1 Attributes and Characterization of Agglomeration 16

2.4 Dissolution 17

2.4.1 Factors of dissolution 17

2.5 Sedimentation Test 18

2.6 EPD (Electrophoresis Deposition) 19

2.6.1 Mechanism of Electrophoretic Deposition EPD 21

2.6.1.1 Particles Accumulation 21

2.6.1.2 Electrostatic Force 21

2.6.1.3 Salting Out 22

2.6.1.4 Neutralization 22

2.6.1.4 Squeezing Out 22

2.7 Electro-Plating 23

2.8 Vapour Deposition 24

2.8.1 Evaporation 24

2.8.2 Transportation 25

2.8.3 Reaction 25

2.8.4 Deposition 25

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vii CHAPTER 3: METHODOLOGY

3.0 Introduction 28

3.1 Formulation of PVDF Suspension 30

3.2 Electrophoretic Deposition of PVDF Film 34

3.3 Surface Microstructure, Thickness Measurement and Elemental Analysis 36

CHAPTER 4: RESULTS AND DICUSSION

4.0 Introduction 39

4.1 Sedimentation test 40

4.2 Surface Microstructures of PVDF Films 42

4.3 FTIR (Fourier transform infrared spectroscopy) 51

CHAPTER 5: CONCLUSION

5.0 Introduction 53

5.1 Conclusion 54

5.2 Recommendations 55

REFERENCES 56

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viii

LIST OF TABLES

Table 1.1 Discovery of Piezoelectric Materials and Their 5 Mechanisms or Applications (Katzir, 2012)

Table 2.1 General Properties of PVDF (Frank, 2014) 10 Table 2.2 Comparison of Smart Materials (Leo, 2002) 11 Table 2.3 Comparison Piezoelectric Constants between PZT-4, 11

BaTiO3, PVDF, and Quartz (Leo, 2002)

Table 2.4 Comparison Between EPD, Electro-Plating and Vapour 26 Deposition (Grainger and Blunt, 1998)

Table 3.1 Range of Times and Temperatures (Kolev, 2012) 33

Table 4.1 Average thickness of PVDF films prepared in MEK 45 based suspensions

Table 4.2 Average thickness of PVDF films prepared in DMF 48 based suspensions (coverage area only)

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LIST OF FIGURES

Figure 1.1 PZT (Lunes, 2010) and BaTiO3 structures 2

(Ersin, 1999)

Figure 2.1 Crystal Structure pf PVDF 9

Figure 2.2 SEM result (Razi, 2014) 13

Figure 2.3 FTIR Spectra of β-PVDF in Perpendicular Stress 13 Deformation (Mano, 2001.

Figure 2.4 Linkage Between Material Properties, Process 14 Parameters, Transformations and Product Attributes

in A Binder Agglomeration Process. (Mort, 2005)

Figure 2.5 Agglomeration Nucleation Mechanisms: (a) Distribution, 15 and (b) Immersion. Granule Properties Typically Depend

on the Mode of Nucleation and Growth. (Morth, 2005)

Figure 2.6 Mechanism of sedimentation process 18

Figure 2.7 Schematic of Electrophoretic Deposition Setup 20 (Razi, 2014).

Figure 2.8 Electroplating Process (Anonymous, 2011). 23

Figure 3.1 Flow Chart of the Experiment 29

Figure 3.2 Programmable Electrophoresis Power Supply System. 34 Figure 3.3 Setup for Elecphoretic Deposition (Razi, 2014). 35

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x Figure 3.4 Cross Section of PVDF Layer on the ITO Glass 35

Substrate

Figure 3.5 UV-Spectroscopy. 36

Figure 3.6 Fourier Transform Infrared Spectroscopy 37

Figure 3.7 Mini Sputter Coater. 38

Figure 3.7 Scanning Electron Microscope. 38

Figure 4.1 Sedimentation results of PVDF particle in MEK based 40 suspensions

Figure 4.2 Sedimentation process of PVDF prepared in DMF based 41 suspensions

Figure 4.3 UV-vis results of PVDF film prepared in MEK based 42 suspensions

Figure 4.4 a) SEM results of PVDF film surface, while b), c) and 43 d) cross section of deposited sample at 53⁰C, 8 hour stirring

condition in MEK based suspension

Figure 4.5 SEM results of PVDF film surface and cross section 44 of deposited sample at 62⁰C, 2 hour stirring condition in

MEK based suspension

Figure 4.6 SEM results of PVDF film surface and cross section 44 of deposited sample at 64⁰C, 8 hour stirring condition in

MEK based suspension

Figure 4.7 UV-vis results of PVDF film prepared in DMF based 45 suspensions

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xi Figure 4.8 SEM results of PVDF film surface and cross section 46

of deposited sample at 80⁰C, 8 hour stirring condition in DMF based suspension

Figure 4.9 SEM results of PVDF film surface and cross section 46 of deposited sample at 120⁰C, 2 hour stirring condition in

DMF based suspension

Figure 4.10 SEM results of PVDF film surface and cross section of 47 deposited sample at 120⁰C, 8 hour stirring condition in

DMF based suspension

Figure 4.11 EDS point analysis of PVDF film prepared using 49 120⁰C, 2 hour stirring conditions

Figure 4.12 EDS point analysis of PVDF film prepared using 49 120⁰C, 8 hour stirring conditions

Figure 4.13 FTIR absorption bands of PVDF film prepared in 51 MEK based suspensions

Figure 4.14 FTIR absorption bands of PVDF film prepared in 52 DMF based suspensions

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xii

LIST ABBREVIATIONS, SYMBOLS AND

NOMENCLATURES

Ba - Barium

BaTiO3 - Barium Titanate

CVD - Chemical Vapour Deposition DC - Direct Current

DMF - Dimethyl Formamide TBp, DMF - Boiling point of DMF

TEx, DMF - Temperature of DMF that used in the experiment

EDS - Energy Dispersive X-ray Spectroscopy EPD - Electrophoresis Deposition

FESEM - Field Emission Scanning Electron Microscopy FTIR - Fourier Transform Infrared

hr - Hour

ITO - Indium Tin Oxide MEK - Methyl Ethyl Ketone TBp, MEK - Boiling point of MEK

TEx, MEK - Temperature of MEK that used in the experiment

O - Oxygen

OM - Optical Microscope

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xiii PVD - Physical Vapour Deposition

PVDF TeFE - PVDF Tetrafluoroethylene PVDF TrFE - PVDF Trifluoroethylene PVDF - Polyvinylidene Fluoride PZT - Lead Zirconate Titanate SEM - Scanning Electron Microscopy

Ti - Titanium

U.S - United State UV - Ultraviolet

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CHAPTER 1

INTRODUCTION

1.0 Introduction

This chapter will introduce the history of piezoelectric, problems statement, objectives, and scopes of project. All the materials involved in piezoelectric properties, especially piezoceramics and piezopolymers also cited in this chapter.

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1.1 History and Background

When a piezoelectric substance is deformed, electric potential is generated. It is called piezoelectric effect. It was demonstrated by the brothers Pierre Curie and Jacques Curie in 1880 (Manbachi et al., 2011). Certain materials can generate a voltage when placed under stress, such as quartz, salt and sugar. These materials had crystal structures with asymmetric dipole moments that would respond to mechanical pressure (Morgan Advance Materials, 2009).

The crystalline structure produce a voltage proportional to the applied mechanical pressure when the crystals are exhibiting direct piezoelectric effect, which is electricity generated from applied stress. Vise-versa, the material exhibits the converse piezoelectric effect, a stress is generated in response to applied electric field (Jacques and Currie, 1881).

In 1945, ferroelectric ceramics were used as capacitor materials, because of its high dielectric strength. First ceramic to be discovered is quartz, followed by BaTiO3

(Barium Titanate) and then PZT (Lead Zirconate Titanate). The ceramics are also exhibiting high piezoelectric constant. However, they have several disadvantages, which are high melting point and low flexibility. Besides, PZT contains toxic lead element.

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3 Figure 1.1 shows the crystal structures of BaTiO3 and Pb (Zr, Ti)O3. PZT consists of

one part of Pb (Lead), one part of Zr (Zirconia) and Ti (Titanium) and three parts of and O (Oxygen). Although PZT has higher permittivity and better crystal structures as piezoelectric applications than BaTiO3, the PZT is toxic. For BaTiO3, it consists of

one part of the Ba (Barium), one part of Ti and three parts of O. They still cannot fulfill the mechanical flexibility requirement of piezoelectric applications.

Then, new piezoceramic families and several types of piezoceramic signal filters were developed such as television, radio and communications equipments were created (Piezo Systems, Inc. 1994). The commercial success of the Japanese efforts has attracted the attention of the industry in many other nations and spurred a new effort to develop successful piezoceramic products in 1980.

In 1969, Kawai has found a strong piezoelectricity in PVDF (Polyvinylidene Fluoride) and it used as an alternative candidate to PZT and BaTiO3 (Kawai and

Heiji, 1969). Piezoceramic materials like PZT and BaTiO3 suffer from mechanical strength and flexibility issues since they are brittle. Besides that, PZT also contain lead that can harm human body. Because of that, these materials were replaced with PVDF. PVDF has no lead content, requires low processing temperature and has good mechanical flexibility. Although PVDF has a better mechanical properties compared to PZT and BaTiO3 vibration sensor application, difficulties might occur in the produce PVDF thick film. Then, other PVDF co-polymers were also reported by Tasaka and Miyata in 1985, including PVDF TrFE (Trifluoroethylene) and PVDF TeFE (Tetrafluoroethylene) (Cohen et al., 1996). The search for perfect piezo material is still going on until now, because the materials that used today still cannot beat the PZT material. Researchers are trying to find the materials that did not contain lead, such as polymer materials.

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4 The piezoelectric material was fabricated in the form of thick film for the purpose of poling process at much higher applied voltage. PVDF is an inert material and need to be poled for piezoelectric applications (Lin et al., 2002). The poling of piezoelectric material is to create electric polarization inside the material so that sufficient ferroelectric strength is achieved for application (Kok et al., 2014). Table 1.1 shows the history of piezomaterials discovery and development over the years. Although many materials that found in nature, have piezoelectric properties, there are gaps between the material properties and the application requirement. Because of these circumstances, development of better piezoelectric is still been continued to improve the properties to fill the needs of the applications.

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5 Table 1.1: Discovery of piezoelectric materials and their mechanisms or applications (Katzir, 2012).

Years Materials Mechanisms/Applications 1880 Tourmaline, Topaz,

Quartz, Rochelle Salt and Cane Sugar

Discovery of electrical charge voltage generated is proportional to the applied mechanical stress on the crystals.

1881 - Piezoelectric effect was mathematically

deduced from fundamental thermodynamic principles.

1917 Quartz The converse piezoelectric effect was used in the first submarine detecting-sonar. 1920 - 1940 Natural Crystal The first generation applications were

produced. Resonating and non-resonating piezoelectric devices.

1939 - 1945 BaTiO3 and PZT These materials possessed superior dielectric

and piezoelectric properties as compared to quartz.

1951 BaTiO3 and PZT Piezoceramic signal filters, which addressed

needs arising in television and radio.

1952 BaTiO3 and PZT _BaTiO

3 have been replaced by PZT.

1969 PVDF This material was found as a piezoelectric material because it has a strong

piezoelectricity. Consider as a replacement for PZT and BaTiO3.

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1.2 Problem Statement

PVDF film deposition faced the crack problem due to weak bonding between PVDF particles, in additional to high residue stresses (Razi, 2014). The densification process by heat treatment did not resolve the cracks problem because of poor bonding between deposited particles. To solve the problems, the improvement of the density of PVDF layer without heat treatment is needed to avoid the crack. The most important issue is the bonding between the deposited polymers must be strong enough to hold the coating. In addition, the substrate for the deposited film must undergo a surface heat treatment using an acid in order to achieve good adhesion between film and substrate.

EPD (Electrophoresis Deposition) has a capability to deposit a multilayer film on complex surface morphologies in a conformal manner at a high deposition throughput, but only with low cost and simple equipment set-up (Foster and White, 2002). However, the properties of the polymeric PVDF film deposited by EPD for accelerometer sensor such as thickness, density, and adhesion, are depended on chemicals formulation and process parameters of the EPD. As the process of EPD involved many parameters such as materials, substance design, formulation, EPD process, annealing temperature and time, study is required to characterize properties of the deposited film, so that an optimization of these parameters to obtain PVDF film with adequate mechanical properties to perform well as the cantilever of an accelerometer sensor (Razi, 2014).

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1.3 Objectives

In order to synthesize crack-free PVDF thick film, the current study embarks on the following objectives:

1. To characterize PVDF suspension prepared by different suspension formulations, processing temperatures and times.

2. To characterize the surface morphology, cross-sectional microstructure and phase composition of PVDF film electrophoretic deposited using the PVDF suspensions stated in objective 1.

1.4 Scopes

In this research, PVDF film will be deposited by EPD method using different PVDF suspension formulation, as well as suspension processing temperatures and times.

To produce a PVDF film, three phases must be completed. The first phase is the preparation of PVDF suspension in organic solvent. For second phase, PVDF suspension was deposited by EPD method on the ITO (Indium Tin Oxide) glass substrate. The last phase is characterizations of the filmed sample. Different parameters will produce PVDF films with different surface morphology, cross-sectional microstructure and phase composition. The appearance of the PVDF particles on the substrate also can be analyzed. Fixed EPD parameters are used for the deposition of all PVDF films. The film will be characterized by using OM (Optical Microscope), FTIR (Fourier Transform Infrared), UV-Visible spectroscopy (Ultraviolet-Visible Spectroscopy) and SEM (Scanning Electron Microscopy).

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CHAPTER 2

LITERATURE REVIEW

2.0 Introduction

This chapter is about the properties of the PVDF, which used as piezoelectric components. Beside that, the methods and mechanisms involved also cited in this chapter.

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2.1 General Material Properties of PVDF

PVDF crystal structures consist of Fluorine, Carbon and Hydrogen elements (refer Figure 2.1). It used as a piezoelectric material to replace BaTiO3 and PZT that

contain lead. By reason of a broad, general properties of the material should be reviewed in advance to ensure it can meet the application requirements. Table 2.1 shows several general properties of PVDF. PVDF contain several unique properties that are not owned by BaTiO3 and PZT. Because of that, PVDF has received

particular attention. One of the most important features is that the PVDF can be easily produced in the form of large thin, flexible sheets and in variety of shapes. The low dielectric permittivity and elastic stiffness of PVDF films at room temperature, resulting in high voltage sensitivity and low acoustic impedance make them attractive for application in piezoelectric devices (Choudhary and Patri, 2009).

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10 Table 2.1: General properties of PVDF (Frank, 2014).

Properties Descriptions

Chemical resistance PVDF is made of composite fluoropolymer resin and ceramic pigment, making it a good chemical resistance

coating. Low melting point

177C

PVDF is an easy melted material and have a low melting point. It’s also easy to be processed compared to other

fluoropolymers. Low density

(1.78 g/cm3₎

PVDF can be molded and is commonly used in the chemical and semiconductor as well as lithium ion batteries. It is also available as a crosslink closed cell foam

which used increasingly in aviation and aerospace applications.

UV resistance, thermal degradation (exposure to 149C).

It have very high fade resistance and ultraviolet resistance in extremely harsh environment. This will allow PVDF to

withstand the surrounding temperature as a film in piezoelectric sensor.

High mechanical strength and

flexibility

PVDF structures have the most stable chemical bond because of the fluoride-carbon bond.

Table 2.2 shows the comparison of smart materials and it is shown piezoelectric polymers are much more durable and sensitive in responding to deformations than ceramics, and also better electric fields. These polymers are not the common that used in polymer films, but used as extreme piezoelectric at the moment. However, PVDF has piezoelectric voltage coefficient 20 times greater than the more common ceramic crystal (Esterly, 2002).

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