i

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.)

by

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.

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.

v

TABLE OF CONTENTS

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

2.1 General Material Properties of PVDF 9

vi

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

2.9 Comparison of Methods 26

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

APPENDIX A

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)

Table 4.3 Percentage of coverage area on the subsrate 50

ix

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

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

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

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

Pb - Lead

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

Zr - Zirconia

1

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.

2

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.

Figure 1.1: PZT (Lunes, 2010) and BaTiO3 structures (Oren, 1999).

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.

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.

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 BaTiO3 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.

6

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).

7

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).

8

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.

9

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).

Figure 2.1: Crystal structures of PVDF (Plastics Europe, n.d.).

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

177C

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 149C).

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).