The effects of stainless steel on the properties of graphite-polypropylene composite for bipolar plate.
SUPERVISOR DECLARATION
" I declare that I have read this thesis and in my opinion this report is sufficient in terms
of scope and qua I ity for the award of the degree of Bachelor of Mechanical Engineering
(Structure & Materials)"
ｾ＠
.............. .
Signature
: ......
Supervisor
: DR. MOHD ZULKEFLI BIN SELA MAT
Date
: 28 JUNE 2013
DR. MOHD ZULKEFLI BIN SELAMAT
Pensyarah Kanan
Fakulti Kejuruteraan Mekanikal
Universiti Teknikal Malaysia Melakl
© Universiti Teknikal Malaysia Melaka
THE EFFECT OF STAINLESS STEEL ON THE PROPERTIES OF GRAPHITEPOLYPROPYLENE COMPOSITE FOR BIPOLAR PLATE
FAIRUZ F AZILLAH BINTI SHUIIlMI
This report is submitted to Faculty of Mechanical Engineering as a
requirements to get award of
Degree of Mechanical Engineering ( Structure & Material)
Faculty of Mechanical Engineering
Universiti Teknikal Malaysia Melaka
JUNE2013
© Universiti Teknikal Malaysia Melaka
ii
DECLARATION
"I hereby declare that the work in this report is my own except for swnmaries
and quotations which have been duly acknowledgment."
ｾ＠
..
:
Signature
: .........
.... ........ ...... .
Author
: FAIRUZ FAZILLAH BINTI SHUHIMI
Date
: 28 JUNE 2013
© Universiti Teknikal Malaysia Melaka
iii
ACKNOWLEDGEMENT
Assalamualaikum w.b.t
Very grateful to Allah S.W.T because of Allah' s endowment, I can execute this
Final Year Project 1 report at the right time. I would like to take this opportunity to
express my deepest heartfelt and thank to all those who have guided and supported me
during my Final Year Project either directly or indirectly.
First of all I would like to thank GOD for this opportunity, and to my parents and
siblings for their love and support. I would like to thank Dr. Mohd Zulkefli bin Selamat
as supervisor, Mr Mohd Syakir bin Ahmad as him assistant researcher and all lecturers
with respect to their direction, guidance, assistance and unselfish support. Special thanks
to my nice appreciation to panels during presentation, Dr. Mohd Fadzli bin Abdollah,
Dr.Olawale Friday, Mr. Omar bin Bapokutty for their valuable advice and nice support
on behalf of me to satisfy this project. Also thanks to all the technicians and staffs from
Department of Mechanical Engineering for their instruction, continuous support and
supervision.
Finally, I would also like to thank those individuals who have contribute to the
success of my training and whose name are not mentioned. They may be my family
members, other FKM staff, friends, and individuals I meet during project progress.
Thank you for all the support and contribution for the success of my Final Year Project
at Universiti Teknikal Malaysia Melaka.
© Universiti Teknikal Malaysia Melaka
iv
ABSTRACT
Over the past decade, rapid progress has been made in the understanding and
development of Conductive Polymer Composites (CPC) as conducting materials. This
project is aimed to study the effects of stainless steel (St) loading on the electrical and
mechanical properties of Graphite (G)/ Stainless steel (St)/ polypropylene (PP)
composite of bipolar plates for polymer electrolyte membrane fuel cells (PEMFC). St is
selected as second filler because it offers good electrical conductivity, high bulk thermal
conductivities, good corrosion resistance and constant particle shape. The analysis of the
G/St/PP composites ratio and the properties of G, St and PP together with the impact of
Graphite (G) as a main filler and Stainless Steel (St) as second filler whereas
polypropylene (PP) as a binder has been carry out. The impact of fillers on the
composite properties was evaluated as well as the ratio of the weight percentage (wt%)
of the composite with 80% for multi-filler material and 20% binder material. The St wt
% is vary from 5 wt % up to 30 wt % of total wt % of multi-filler materials. After
formation of composite through compression molding, the effects of St in G/St/PP
composite have been determined through various tests such as electrical conductivity,
flexure strength, density and hardness before can be used as composition of G/St/PP
composite for bipolar plate. The result showed the analysis for Flexural Strength, Bulk
Density and Shore Hardness meet the required characteristics of bipolar plate as in the
Department of Energy (DOE). But for electrical conductivity, the results showed a very
slight increase which is less than 1OOS/cm.
© Universiti Teknikal Malaysia Melaka
v
ABSTRAK
Lebih sedekad yang lalu, kemajuan pesat telah dibuat dalam memahami dan
pembangunan konduktif Polimer Komposit (CPC) yang mengendalikan bahan-bahan.
Projek ini bertujuan untuk mengkaji kesan daripada keluli tahan karat (St) pada sifatsifat elektrik dan mekanikal Grafit (G) I keluli tahan karat (St) I polipropilena (PP)
komposit plat dwikutub bagi polimer elektrolit sel bahan api membran. St dipilih sebagai
pengisi kedua kerana ia menawarkan kekonduksian elektrik yang baik, konduktiviti haba
yang tinggi, ketahanan kakisan yang baik dan bentuk zarah yang berterusan. Analisis
nisbah komposit G I St I PP dan sifat-sifat G, St PP dan bersama-sama dengan kesan
Grafit (G) sebagai pengisi utama dan keluli tahan karat (St) sebagai pengisi kedua
manakala polipropilena (PP) sebagai pengikat telah menjalankan. Kesan pengisi pada
sifat-sifat komposit telah dinilai serta nisbah peratusan berat (% berat) dengan 80%
untuk bahan pelbagai pengisi dan 20% bahan pengikat. Berat St°/o yang berbeza-beza
dari 5% sehingga 30% daripada jumlah berat bahan pelbagai pengisi. Selepas
pembentukan komposit melalui pengacuan mampatan, kesan St dalam G I St I PP
komposit telah ditentukan melalui pelbagai ujian seperti kekonduksian elektrik,
kekuatan lenturan, kepadatan dan kekerasan sebelum boleh digunakan sebagai
komposisi G I St I PP gubahan plat dwikutub. Hasilnya menunjukkan analisis untuk
kekuatan lenturan, ketumpatan dan kekerasan memenuhi ciri-ciri yang diperlukan plat
dwikutub oleh Jabatan Tenaga. Tetapi bagi kekonduksian elektrik, keputusan
menunjukkan peningkatan yang sangat sedikit iaitu kurang daripada 1OOS/cm.
© Universiti Teknikal Malaysia Melaka
vi
CONTENT
CHAPTER
TITLE
PAGES
TITLE PAGE
CHAPTER I
DECLARATION
11
ACKNOWLEDGEMENT
lll
ABSTRACT
iv
ABSTRAK
v
CONTENT
vi-ix
LIST OF FIGURE
X-Xl
LIST OF TABLE
XU
LIST OF APPENDIX
xiii
LIST OF SYMBOLS
xiv
LIST OF ABBREVIATION
xv
INTRODUCTION
1.1
BACKGROUND
1.1.1
1
Proton exchange membrane
fuel cell
3
1. I .1.1 Polymer Electrolyte
Membrane Fuel Cell
1.1.2
Operation
4
Component of PEMFC
5
1.1 .2.1 Membrane Electrolyte
Assembly (MEA)
© Universiti Teknikal Malaysia Melaka
7
vii
1.1.2.2 Catalysts
CHAPTER2
8
1.2
OBJECTIVE
8
1.3
SCOPE OF STUDY
9
1.4
PROBLEM STATEMENT
9
LITERATURE REVIEW
2.1
CONDUCTIVE POLYMER
COMPOSITES
10
2.1.1 Conductively Filled Polymers
11
2.1.2 Polymers Filled with Conductive
12
Solids
2.2
BIPOLAR PLATE MATERIALS
2.2.1
2.2.2
15
Filler
2.2.1. l Graphite
15
2.2.1.2Stainless Steel
19
Binder
2.2.2.1 Polypropylene
2.3
14
23
23
FABRICATION OF BIPOLAR PLATE
25
2.3.1
Injection Molding
25
2.3.1.1 Equipment
26
2.3.1.2 Power Requirements
26
Compression Molding
27
2.3.2.1 Basic Process of
27
2.3.2
Compression Molqing
2.4
2.3.2.2 Advantages
28
2.3.2.3 Disadvantage
28
TESTING METHOD
29
2.4.1
Electrical Properties
29
2.4.2
Mechanical Properties
30
© Universiti Teknikal Malaysia Melaka
viii
CHAPTER3
METHODOLOGY
3.1
CHAPTER4
CHARACTERIZATION OF
RAW MATERI.AL
33
3.2
PRE-MIXING
35
3.3
MELT COMPOUNDING
36
3.4
CRUSH AND PULVERIZE
37
3.5
COMPRESSION MOLDING
38
3.6
TESTING
3.6.1
Electrical Properties
3.6.2
Mechanical Properties
3.6.2.1 Flexural Testing
42
3.6.2.2 Bulk Density Testing
43
3.6.2.3 Shore Hardness Testing
43
RESULT AND ANALYSIS
4.1
ELECTRICAL CONDUCTIVITY
TEST RESULT
4.1.1
44
Determination of Electrical
Conductivity
CHAPTERS
41
45
4.2
FLEXURAL TEST
47
4.3
BULK DENSITY
48
4.4
SHORE HARDNESS
49
DISCUSSION
5.1
DISCUSSION OF RESULT
5.1.1
Electrical Conductivity Testing
51
5.1.2
Flexural Testing
52
5.1.3
Bulk Density Testing
52
5.1.4
Shore Hardness Testing
53
© Universiti Teknikal Malaysia Melaka
ix
5.2
DISCUSSION OF PROBLEM
ENCOUNTERED
5.2.1
Materials flows out of the mold
54
5.2.2
Material attached to the mold
54
5.2.3
Mold plate loose
55
5.2.4
Surface of sample not uniform
and broken
5.3
CHAPTER6
SOLUTIONS
55
56
CONCLUSION AND RECOMMENDATION
6.1
CONCLUSION
57
6.2
RECOMMENDATION
58
REFERENCES
59
BIBLIOGRAPHY
65
APPENDIX
67
© Universiti Teknikal Malaysia Melaka
x
LIST OF FIGURE
BIL
TITLE
PAGE
Figure I.I
Fuel cell
2
Figure I.2
Polymer Electrolyte Membrane Fuel Cell (PEMFC)
3
Figure I.3
Operation of PEMFC
4
Figure I.4
The illustration of components of PEMFC
5
Figure I.5
Bipolar Plates
6
Figure 2.I
Dependence of composite conductivity on the volume
I2
fraction of conductive fillers
Figure 2.2
Schematic representation of conductive particles dispersed 13
in a polymer matrix at different particle volume fractions
Figure 2.3
Classification of materials for BPs used in PEM fuel cells
I4
Figure 2.4
Graphite Specimen
I6
Figure 2.5
Graphite Unit Cell
I7
Figure 2.6
Stainless steel AISI 3I6 (Fe/CrI8/NilO/Mo3)
20
Figure 2.7
Polypropylene
23
Figure 2.8
Chemical structures for polypropylene
23
Figure 2.9
Injection Molding Machine
25
Figure 2.IO
Jandel Four Point Probe
29
Figure 2.I I
Zwick Shore hardness tester and flexural testing machine
30
Figure 2.I2
Density Meter Tester
30
Figure 3.I
Flow Chart Methodology
32
Figure 3.2
Powder of material (a) G, (b) St and (c) PP
33
© Universiti Teknikal Malaysia Melaka
xi
Figure 3.3
Measured the weight of graphite and stainless
34
steel due the percentage
Figure 3.4
Ball Mill machine
35
Figure 3.5
Steel Ball
35
Figure 3.6
Measure the weight of St/G and PP
36
Figure 3.7
Internal Mixer Machine
36
Figure 3.8
Outcomes from Internal Mixer Machine (St/GIPP)
37
Figure 3.9
Crusher machine
37
Figure 3.10
Outcomes of crusher process
37
Figure 3.11
Centrifugal Mill machine
38
Figure 3.12
Outcomes of pulverize process
38
Figure 3.13
Four-Point Probe Tester
41
Figure 3.14
Cutter machine
42
Figure 3.15
Standard sizes for Flexural
42
Figure 3.16
Three Point Flexural Test
42
Figure 3.17
Setting the sample to the supporting span
42
Figure 3.18
Electronic Densimeter
43
Figure 3.19
Standard size for density test
43
Figure 3.20
Digital Shore Hardness
43
Figure 4.1
Graph of conductivity versus St wt%
45
Figure 4.2
Graph of flexural strength versus St wt%
47
Figure 4.3
Graph of Density versus St wt.%
48
Figure 4.4
Graph of shore hardness versus St wt%
49
Figure 5.1
Materials flow out of the mold
54
Figure 5.2
Material attached to the mold
54
Figure 5.3
Mold plate loose
55
Figure 5.4
Surface of sample broken
55
Figure 5.5
Mold plate sprayed with lubricant oil
56
© Universiti Teknikal Malaysia Melaka
xii
LIST OFTABLE
BIL
TITLE
PAGE
Table 2.1
Principal property of filler
16
Table 2.2
Composition ranges for 316L stainless steel
22
Table 2.3
Mechanical properties of 316L stainless steel
22
Table 2.4
Typical physical properties for 316L grade
stainless steels
22
Table 2.5
Properties of polypropylene
24
Table 2.6
The power requirement of injection molding by
26
different material
Table 3.1
Raw material properties of G/St/PP
33
Table 3.2
Composition based on weight percentages
34
Table 4.1
Average result for Conductivity of St/GIPP
45
Table 4.2
Data from top and bottom of composite 20% St
45
Table 4.3
Average result for Flexural Strength of St/GIPP
47
Table 4.4
Bulk Density of St/GIPP
48
Table 4.5
Shore hardness St/GIPP
48
Table 5.1
U.S Department of Energy (US DOE)
51
© Universiti Teknikal Malaysia Melaka
xiii
LIST OF APPENDIX
BIL
TITLE
PAGE
A
FLOW CHART OF STUDY
67
B
GANTT CHART FINAL YEAR PROJECT 1 & 2
68
c
ASTM C611 ELECTRICAL RESISTIVITY
69
D
ASTM D790-03 FLEXURAL TEST
71
E
ASTM C559-90 BULK DENSITY
77
F
ASTM C886-98 HARDNESS
78
© Universiti Teknikal Malaysia Melaka
xiv
LIST OF SYMBOL
PEMFC
= Proton Exchange Membrane Fuel Cell I Polymer Electrolyte
Membrane Fuel Cell
PEM
= Polymer Electrolyte Membrane
BPs
= Bipolar Plate
DC
= Direct Current
H20
=Hydrogen
02
=Oxygen
MEA
= Membrane Electrolyte Assembly
G
=Graphite
St
= Stainless Steel
pp
= Polypropylene
PPS
= Polyphenylene sulfide
PVDF
= Polyvinylidene fluoride
CPCs
= Conductive Polymer Composites
IP Cs
= Inherently Conducting Polymers
SPEs
= Solid Polymer Electrolytes
Cr
= Chromium
Ni
=Nickel
Mo
=
LDPE
= Low-Density Polyethylene
HDPE
= High-Density Polyethylene
MFR
= Melt Flow Rate
MFI
= Melt Flow Index
DOE
=US-Department of Energy
Molybdenum
© Universiti Teknikal Malaysia Melaka
xv
LIST OF ABBREVIATION
Wt.%
= Weight Percentage
Siem
= Siemens/centimeter
MP a
= Mega Pascal
Cm
= centimeter
µA
= micron Ampere
g/cm 3
= gram/centimeter3
W ·m-
= Watt per metre
µA cm/\ (-2)
=Micro ampere(s) per square centimeter
µm
= micrometer
nm
=nanometer
ncm
= ohm-centimeter
E
=Young's Modulus
mK
= milli Kelvin
oc
= Degree Celsius
© Universiti Teknikal Malaysia Melaka
1
CHAPTER 1
INTRODUCTION
1.1
BACKGROUND
One of the maJor factors limiting fuel cell commercialization is the
development of bipolar plates, which are one of PEMFC's key components. Several
types of materials are currently used in bipolar plates, including non-porous graphite
plates, metallic plates with or without coating and a number of composite plates.
The bipolar plate is one of the most important components in a PEM fuel cell.
A polymer composite bipolar plate possessing high strength and high stiffness has been
developed by making use of carbon fiber network in a specific form as the filler
component. The bipolar plates are in weight and volume the major part of PEM fuel cell
stack, and also a significant effect to the stack cost.
© Universiti Teknikal Malaysia Melaka
2
Figure 1.1: Fuel cell
So far, many different materials for bipolar plates have been investigated and an
alternative solution consists in polymer composite that combine the process ability and
mechanical properties of the polymeric phase and the conductivity of the carbon fillers.
Both thermo-set resins and thermoplastics were considered and combined to many
different carbon fillers. [ 1]
The interests and limitations of these formulations are presented in terms of
process ability and most relevant properties. A composite material is made by combining
two or more materials to give a unique combination of improved properties, such that
each component retains its physical identity.
In order to improve their commercial liability, many scientific and
technological efforts are being performed on fuel cell systems. On the technical point of
view, bipolar plates should fulfill functional challenges besides ensuring the mechanical
strength of the stack. As a result an optimal material for bipolar plate application should
present an unusual balance of properties, essentially high electrical conductivity and
good mechanical strength.
© Universiti Teknikal Malaysia Melaka
3
1.1.1
Proton exchange membrane fuel cell
Proton exchange membrane fuel cell (PEMFC), also known as polymer
electrolyte membrane (PEM) fuel cells are a type of fuel cell being developed for
transport applications as well as for stationary fuel cell applications and portable fuel
cell applications. Their distinguishing features include lower temperature/pressure
ranges (50 to I 00 °C) and a special polymer electrolyte membrane.
PEMFC are electrochemical devices that convert the chemical energy of
reactants (a fuel and an oxidant) directly to electrical energy in the form of low voltage
direct current (DC) electricity and heat. They have been receiving significant attention
due to their high power density, energy efficiency, and environmentally friendly
characteristics. [2]
Power
End-plate
gos and cooling manifold
Bipolar n ow-rlate
interconnect
- --
Membrane
ｬＺ･｣ｲｯＩｾｃ＠
sscmbl}
tMEA)
llcat
Figure 1.2: Polymer El ectrolyte Membrane Fuel Cell (PEMFC) [7]
© Universiti Teknikal Malaysia Melaka
4
1.1.1 .1 Polymer Electrolyte Membrane Fuel Cell Operation
I.
Pure hydrogen constantly flows from a simple cylinder containing
compressed hydrogen into the fuel cell and onto the anode it is then split
into hydrogen ions and electrons.
2.
The electrons cannot pass through the electrolyte therefore ; they pass
through the external circuit creating an electric charge.
3.
The electrolyte is sandwiched between the anode and cathode, which 1s
permeable to protons but does not conduct electrons. Hydrogen ions
(protons) permeate across the electrolyte to the cathode. Electrons flow
through an external circuit and provide power.
4.
Oxygen is fed into the fuel cell onto the cathode (positive electrode). The
cathode combines electrons, protons and oxygen to form the by product
which is water. The water then leaves the cell . This is a continuous process
so as hydrogen and oxygen is supplied. [3]
. -. --
Ol (Oxygen)
from Air
HHt(8S"C)
Watu or Air Cool•d
Flow Fi•ld
Plate
ｾＭ
Gas Diffusion
Elec:tro
" I declare that I have read this thesis and in my opinion this report is sufficient in terms
of scope and qua I ity for the award of the degree of Bachelor of Mechanical Engineering
(Structure & Materials)"
ｾ＠
.............. .
Signature
: ......
Supervisor
: DR. MOHD ZULKEFLI BIN SELA MAT
Date
: 28 JUNE 2013
DR. MOHD ZULKEFLI BIN SELAMAT
Pensyarah Kanan
Fakulti Kejuruteraan Mekanikal
Universiti Teknikal Malaysia Melakl
© Universiti Teknikal Malaysia Melaka
THE EFFECT OF STAINLESS STEEL ON THE PROPERTIES OF GRAPHITEPOLYPROPYLENE COMPOSITE FOR BIPOLAR PLATE
FAIRUZ F AZILLAH BINTI SHUIIlMI
This report is submitted to Faculty of Mechanical Engineering as a
requirements to get award of
Degree of Mechanical Engineering ( Structure & Material)
Faculty of Mechanical Engineering
Universiti Teknikal Malaysia Melaka
JUNE2013
© Universiti Teknikal Malaysia Melaka
ii
DECLARATION
"I hereby declare that the work in this report is my own except for swnmaries
and quotations which have been duly acknowledgment."
ｾ＠
..
:
Signature
: .........
.... ........ ...... .
Author
: FAIRUZ FAZILLAH BINTI SHUHIMI
Date
: 28 JUNE 2013
© Universiti Teknikal Malaysia Melaka
iii
ACKNOWLEDGEMENT
Assalamualaikum w.b.t
Very grateful to Allah S.W.T because of Allah' s endowment, I can execute this
Final Year Project 1 report at the right time. I would like to take this opportunity to
express my deepest heartfelt and thank to all those who have guided and supported me
during my Final Year Project either directly or indirectly.
First of all I would like to thank GOD for this opportunity, and to my parents and
siblings for their love and support. I would like to thank Dr. Mohd Zulkefli bin Selamat
as supervisor, Mr Mohd Syakir bin Ahmad as him assistant researcher and all lecturers
with respect to their direction, guidance, assistance and unselfish support. Special thanks
to my nice appreciation to panels during presentation, Dr. Mohd Fadzli bin Abdollah,
Dr.Olawale Friday, Mr. Omar bin Bapokutty for their valuable advice and nice support
on behalf of me to satisfy this project. Also thanks to all the technicians and staffs from
Department of Mechanical Engineering for their instruction, continuous support and
supervision.
Finally, I would also like to thank those individuals who have contribute to the
success of my training and whose name are not mentioned. They may be my family
members, other FKM staff, friends, and individuals I meet during project progress.
Thank you for all the support and contribution for the success of my Final Year Project
at Universiti Teknikal Malaysia Melaka.
© Universiti Teknikal Malaysia Melaka
iv
ABSTRACT
Over the past decade, rapid progress has been made in the understanding and
development of Conductive Polymer Composites (CPC) as conducting materials. This
project is aimed to study the effects of stainless steel (St) loading on the electrical and
mechanical properties of Graphite (G)/ Stainless steel (St)/ polypropylene (PP)
composite of bipolar plates for polymer electrolyte membrane fuel cells (PEMFC). St is
selected as second filler because it offers good electrical conductivity, high bulk thermal
conductivities, good corrosion resistance and constant particle shape. The analysis of the
G/St/PP composites ratio and the properties of G, St and PP together with the impact of
Graphite (G) as a main filler and Stainless Steel (St) as second filler whereas
polypropylene (PP) as a binder has been carry out. The impact of fillers on the
composite properties was evaluated as well as the ratio of the weight percentage (wt%)
of the composite with 80% for multi-filler material and 20% binder material. The St wt
% is vary from 5 wt % up to 30 wt % of total wt % of multi-filler materials. After
formation of composite through compression molding, the effects of St in G/St/PP
composite have been determined through various tests such as electrical conductivity,
flexure strength, density and hardness before can be used as composition of G/St/PP
composite for bipolar plate. The result showed the analysis for Flexural Strength, Bulk
Density and Shore Hardness meet the required characteristics of bipolar plate as in the
Department of Energy (DOE). But for electrical conductivity, the results showed a very
slight increase which is less than 1OOS/cm.
© Universiti Teknikal Malaysia Melaka
v
ABSTRAK
Lebih sedekad yang lalu, kemajuan pesat telah dibuat dalam memahami dan
pembangunan konduktif Polimer Komposit (CPC) yang mengendalikan bahan-bahan.
Projek ini bertujuan untuk mengkaji kesan daripada keluli tahan karat (St) pada sifatsifat elektrik dan mekanikal Grafit (G) I keluli tahan karat (St) I polipropilena (PP)
komposit plat dwikutub bagi polimer elektrolit sel bahan api membran. St dipilih sebagai
pengisi kedua kerana ia menawarkan kekonduksian elektrik yang baik, konduktiviti haba
yang tinggi, ketahanan kakisan yang baik dan bentuk zarah yang berterusan. Analisis
nisbah komposit G I St I PP dan sifat-sifat G, St PP dan bersama-sama dengan kesan
Grafit (G) sebagai pengisi utama dan keluli tahan karat (St) sebagai pengisi kedua
manakala polipropilena (PP) sebagai pengikat telah menjalankan. Kesan pengisi pada
sifat-sifat komposit telah dinilai serta nisbah peratusan berat (% berat) dengan 80%
untuk bahan pelbagai pengisi dan 20% bahan pengikat. Berat St°/o yang berbeza-beza
dari 5% sehingga 30% daripada jumlah berat bahan pelbagai pengisi. Selepas
pembentukan komposit melalui pengacuan mampatan, kesan St dalam G I St I PP
komposit telah ditentukan melalui pelbagai ujian seperti kekonduksian elektrik,
kekuatan lenturan, kepadatan dan kekerasan sebelum boleh digunakan sebagai
komposisi G I St I PP gubahan plat dwikutub. Hasilnya menunjukkan analisis untuk
kekuatan lenturan, ketumpatan dan kekerasan memenuhi ciri-ciri yang diperlukan plat
dwikutub oleh Jabatan Tenaga. Tetapi bagi kekonduksian elektrik, keputusan
menunjukkan peningkatan yang sangat sedikit iaitu kurang daripada 1OOS/cm.
© Universiti Teknikal Malaysia Melaka
vi
CONTENT
CHAPTER
TITLE
PAGES
TITLE PAGE
CHAPTER I
DECLARATION
11
ACKNOWLEDGEMENT
lll
ABSTRACT
iv
ABSTRAK
v
CONTENT
vi-ix
LIST OF FIGURE
X-Xl
LIST OF TABLE
XU
LIST OF APPENDIX
xiii
LIST OF SYMBOLS
xiv
LIST OF ABBREVIATION
xv
INTRODUCTION
1.1
BACKGROUND
1.1.1
1
Proton exchange membrane
fuel cell
3
1. I .1.1 Polymer Electrolyte
Membrane Fuel Cell
1.1.2
Operation
4
Component of PEMFC
5
1.1 .2.1 Membrane Electrolyte
Assembly (MEA)
© Universiti Teknikal Malaysia Melaka
7
vii
1.1.2.2 Catalysts
CHAPTER2
8
1.2
OBJECTIVE
8
1.3
SCOPE OF STUDY
9
1.4
PROBLEM STATEMENT
9
LITERATURE REVIEW
2.1
CONDUCTIVE POLYMER
COMPOSITES
10
2.1.1 Conductively Filled Polymers
11
2.1.2 Polymers Filled with Conductive
12
Solids
2.2
BIPOLAR PLATE MATERIALS
2.2.1
2.2.2
15
Filler
2.2.1. l Graphite
15
2.2.1.2Stainless Steel
19
Binder
2.2.2.1 Polypropylene
2.3
14
23
23
FABRICATION OF BIPOLAR PLATE
25
2.3.1
Injection Molding
25
2.3.1.1 Equipment
26
2.3.1.2 Power Requirements
26
Compression Molding
27
2.3.2.1 Basic Process of
27
2.3.2
Compression Molqing
2.4
2.3.2.2 Advantages
28
2.3.2.3 Disadvantage
28
TESTING METHOD
29
2.4.1
Electrical Properties
29
2.4.2
Mechanical Properties
30
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CHAPTER3
METHODOLOGY
3.1
CHAPTER4
CHARACTERIZATION OF
RAW MATERI.AL
33
3.2
PRE-MIXING
35
3.3
MELT COMPOUNDING
36
3.4
CRUSH AND PULVERIZE
37
3.5
COMPRESSION MOLDING
38
3.6
TESTING
3.6.1
Electrical Properties
3.6.2
Mechanical Properties
3.6.2.1 Flexural Testing
42
3.6.2.2 Bulk Density Testing
43
3.6.2.3 Shore Hardness Testing
43
RESULT AND ANALYSIS
4.1
ELECTRICAL CONDUCTIVITY
TEST RESULT
4.1.1
44
Determination of Electrical
Conductivity
CHAPTERS
41
45
4.2
FLEXURAL TEST
47
4.3
BULK DENSITY
48
4.4
SHORE HARDNESS
49
DISCUSSION
5.1
DISCUSSION OF RESULT
5.1.1
Electrical Conductivity Testing
51
5.1.2
Flexural Testing
52
5.1.3
Bulk Density Testing
52
5.1.4
Shore Hardness Testing
53
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ix
5.2
DISCUSSION OF PROBLEM
ENCOUNTERED
5.2.1
Materials flows out of the mold
54
5.2.2
Material attached to the mold
54
5.2.3
Mold plate loose
55
5.2.4
Surface of sample not uniform
and broken
5.3
CHAPTER6
SOLUTIONS
55
56
CONCLUSION AND RECOMMENDATION
6.1
CONCLUSION
57
6.2
RECOMMENDATION
58
REFERENCES
59
BIBLIOGRAPHY
65
APPENDIX
67
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x
LIST OF FIGURE
BIL
TITLE
PAGE
Figure I.I
Fuel cell
2
Figure I.2
Polymer Electrolyte Membrane Fuel Cell (PEMFC)
3
Figure I.3
Operation of PEMFC
4
Figure I.4
The illustration of components of PEMFC
5
Figure I.5
Bipolar Plates
6
Figure 2.I
Dependence of composite conductivity on the volume
I2
fraction of conductive fillers
Figure 2.2
Schematic representation of conductive particles dispersed 13
in a polymer matrix at different particle volume fractions
Figure 2.3
Classification of materials for BPs used in PEM fuel cells
I4
Figure 2.4
Graphite Specimen
I6
Figure 2.5
Graphite Unit Cell
I7
Figure 2.6
Stainless steel AISI 3I6 (Fe/CrI8/NilO/Mo3)
20
Figure 2.7
Polypropylene
23
Figure 2.8
Chemical structures for polypropylene
23
Figure 2.9
Injection Molding Machine
25
Figure 2.IO
Jandel Four Point Probe
29
Figure 2.I I
Zwick Shore hardness tester and flexural testing machine
30
Figure 2.I2
Density Meter Tester
30
Figure 3.I
Flow Chart Methodology
32
Figure 3.2
Powder of material (a) G, (b) St and (c) PP
33
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xi
Figure 3.3
Measured the weight of graphite and stainless
34
steel due the percentage
Figure 3.4
Ball Mill machine
35
Figure 3.5
Steel Ball
35
Figure 3.6
Measure the weight of St/G and PP
36
Figure 3.7
Internal Mixer Machine
36
Figure 3.8
Outcomes from Internal Mixer Machine (St/GIPP)
37
Figure 3.9
Crusher machine
37
Figure 3.10
Outcomes of crusher process
37
Figure 3.11
Centrifugal Mill machine
38
Figure 3.12
Outcomes of pulverize process
38
Figure 3.13
Four-Point Probe Tester
41
Figure 3.14
Cutter machine
42
Figure 3.15
Standard sizes for Flexural
42
Figure 3.16
Three Point Flexural Test
42
Figure 3.17
Setting the sample to the supporting span
42
Figure 3.18
Electronic Densimeter
43
Figure 3.19
Standard size for density test
43
Figure 3.20
Digital Shore Hardness
43
Figure 4.1
Graph of conductivity versus St wt%
45
Figure 4.2
Graph of flexural strength versus St wt%
47
Figure 4.3
Graph of Density versus St wt.%
48
Figure 4.4
Graph of shore hardness versus St wt%
49
Figure 5.1
Materials flow out of the mold
54
Figure 5.2
Material attached to the mold
54
Figure 5.3
Mold plate loose
55
Figure 5.4
Surface of sample broken
55
Figure 5.5
Mold plate sprayed with lubricant oil
56
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xii
LIST OFTABLE
BIL
TITLE
PAGE
Table 2.1
Principal property of filler
16
Table 2.2
Composition ranges for 316L stainless steel
22
Table 2.3
Mechanical properties of 316L stainless steel
22
Table 2.4
Typical physical properties for 316L grade
stainless steels
22
Table 2.5
Properties of polypropylene
24
Table 2.6
The power requirement of injection molding by
26
different material
Table 3.1
Raw material properties of G/St/PP
33
Table 3.2
Composition based on weight percentages
34
Table 4.1
Average result for Conductivity of St/GIPP
45
Table 4.2
Data from top and bottom of composite 20% St
45
Table 4.3
Average result for Flexural Strength of St/GIPP
47
Table 4.4
Bulk Density of St/GIPP
48
Table 4.5
Shore hardness St/GIPP
48
Table 5.1
U.S Department of Energy (US DOE)
51
© Universiti Teknikal Malaysia Melaka
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LIST OF APPENDIX
BIL
TITLE
PAGE
A
FLOW CHART OF STUDY
67
B
GANTT CHART FINAL YEAR PROJECT 1 & 2
68
c
ASTM C611 ELECTRICAL RESISTIVITY
69
D
ASTM D790-03 FLEXURAL TEST
71
E
ASTM C559-90 BULK DENSITY
77
F
ASTM C886-98 HARDNESS
78
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xiv
LIST OF SYMBOL
PEMFC
= Proton Exchange Membrane Fuel Cell I Polymer Electrolyte
Membrane Fuel Cell
PEM
= Polymer Electrolyte Membrane
BPs
= Bipolar Plate
DC
= Direct Current
H20
=Hydrogen
02
=Oxygen
MEA
= Membrane Electrolyte Assembly
G
=Graphite
St
= Stainless Steel
pp
= Polypropylene
PPS
= Polyphenylene sulfide
PVDF
= Polyvinylidene fluoride
CPCs
= Conductive Polymer Composites
IP Cs
= Inherently Conducting Polymers
SPEs
= Solid Polymer Electrolytes
Cr
= Chromium
Ni
=Nickel
Mo
=
LDPE
= Low-Density Polyethylene
HDPE
= High-Density Polyethylene
MFR
= Melt Flow Rate
MFI
= Melt Flow Index
DOE
=US-Department of Energy
Molybdenum
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LIST OF ABBREVIATION
Wt.%
= Weight Percentage
Siem
= Siemens/centimeter
MP a
= Mega Pascal
Cm
= centimeter
µA
= micron Ampere
g/cm 3
= gram/centimeter3
W ·m-
= Watt per metre
µA cm/\ (-2)
=Micro ampere(s) per square centimeter
µm
= micrometer
nm
=nanometer
ncm
= ohm-centimeter
E
=Young's Modulus
mK
= milli Kelvin
oc
= Degree Celsius
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1
CHAPTER 1
INTRODUCTION
1.1
BACKGROUND
One of the maJor factors limiting fuel cell commercialization is the
development of bipolar plates, which are one of PEMFC's key components. Several
types of materials are currently used in bipolar plates, including non-porous graphite
plates, metallic plates with or without coating and a number of composite plates.
The bipolar plate is one of the most important components in a PEM fuel cell.
A polymer composite bipolar plate possessing high strength and high stiffness has been
developed by making use of carbon fiber network in a specific form as the filler
component. The bipolar plates are in weight and volume the major part of PEM fuel cell
stack, and also a significant effect to the stack cost.
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2
Figure 1.1: Fuel cell
So far, many different materials for bipolar plates have been investigated and an
alternative solution consists in polymer composite that combine the process ability and
mechanical properties of the polymeric phase and the conductivity of the carbon fillers.
Both thermo-set resins and thermoplastics were considered and combined to many
different carbon fillers. [ 1]
The interests and limitations of these formulations are presented in terms of
process ability and most relevant properties. A composite material is made by combining
two or more materials to give a unique combination of improved properties, such that
each component retains its physical identity.
In order to improve their commercial liability, many scientific and
technological efforts are being performed on fuel cell systems. On the technical point of
view, bipolar plates should fulfill functional challenges besides ensuring the mechanical
strength of the stack. As a result an optimal material for bipolar plate application should
present an unusual balance of properties, essentially high electrical conductivity and
good mechanical strength.
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3
1.1.1
Proton exchange membrane fuel cell
Proton exchange membrane fuel cell (PEMFC), also known as polymer
electrolyte membrane (PEM) fuel cells are a type of fuel cell being developed for
transport applications as well as for stationary fuel cell applications and portable fuel
cell applications. Their distinguishing features include lower temperature/pressure
ranges (50 to I 00 °C) and a special polymer electrolyte membrane.
PEMFC are electrochemical devices that convert the chemical energy of
reactants (a fuel and an oxidant) directly to electrical energy in the form of low voltage
direct current (DC) electricity and heat. They have been receiving significant attention
due to their high power density, energy efficiency, and environmentally friendly
characteristics. [2]
Power
End-plate
gos and cooling manifold
Bipolar n ow-rlate
interconnect
- --
Membrane
ｬＺ･｣ｲｯＩｾｃ＠
sscmbl}
tMEA)
llcat
Figure 1.2: Polymer El ectrolyte Membrane Fuel Cell (PEMFC) [7]
© Universiti Teknikal Malaysia Melaka
4
1.1.1 .1 Polymer Electrolyte Membrane Fuel Cell Operation
I.
Pure hydrogen constantly flows from a simple cylinder containing
compressed hydrogen into the fuel cell and onto the anode it is then split
into hydrogen ions and electrons.
2.
The electrons cannot pass through the electrolyte therefore ; they pass
through the external circuit creating an electric charge.
3.
The electrolyte is sandwiched between the anode and cathode, which 1s
permeable to protons but does not conduct electrons. Hydrogen ions
(protons) permeate across the electrolyte to the cathode. Electrons flow
through an external circuit and provide power.
4.
Oxygen is fed into the fuel cell onto the cathode (positive electrode). The
cathode combines electrons, protons and oxygen to form the by product
which is water. The water then leaves the cell . This is a continuous process
so as hydrogen and oxygen is supplied. [3]
. -. --
Ol (Oxygen)
from Air
HHt(8S"C)
Watu or Air Cool•d
Flow Fi•ld
Plate
ｾＭ
Gas Diffusion
Elec:tro