Introduction to Conductive Polymer Composites

191 Pages·2011·4.329 MB·English

by  iPolycond Consortium

An Introduction to
Conductive Polymer
Composites
http://www.ipolycond.org/
First Published in 2011 by Smithers Rapra for the iPolyCond Leonardo Project Consortium
©2011, iPolyCond
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shall be liable for any loss, damage or liability directly or indirectly caused or alleged
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ISBN: 978-1-84735-588-1 (Hardback)
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P
roject Information
PolyCond
‘Creating a competitive edge for the European polymer processing industry by driving
new added-value products with conducting polymers’.
Project Description
The objective of the PolyCond project was to develop conductive plastic composites
that are eco-friendly, cost effective and of high added value. This was achieved
through an ambitious multidisciplinary approach developing new, radically innovative,
knowledge-based and sustainable products for protection against the effects of
electromagnetic interference (EMI) and electrostatic discharge (ESD).
Research was based on the compounding of engineering polymers and inherently
conductive polymers (ICP) with improved conductivity, or hybrid systems of ICP
with conductive nanotubes and other fibrous conductors. Innovative processing
technologies specifically tailored to the new materials were also developed. PolyCond
aimed to dramatically extend the current performance and processability of ICP and
alternative materials to enable significant replacement of metals in EMI shielding and
ESD protection applications.
The main objectives were to:
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matrices
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final product
The PolyCond project ran from February 2005 to January 2009.
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An Introduction to Conductive Polymer Composites
PolyCond Participants
The participants are listed below:
AIMPLAS, Spain
BPF, UK
Bond voor Materialenkennis, Netherlands
Colorex, Netherlands
CRC-HAS, Hungary
EuPC, Belgium
Faperin, Spain
Helsinki University of Technology, Finland
Intermedic, Spain
MAVESZ, Hungary
Molespol, Spain
Panipol, Finland
Promolding, Netherlands
Rondol, UK
Smithers Rapra, UK
TBA-ECP, UK
TNO, Netherlands
VTT, Finland
WTP, UK
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Project Information
Project Progress and Results
This table shows the range of polymers developed in the PolyCond project:
Base material Benefits
Polypropylene Good toughness possible with polyaniline
Polyamide 12 Wire coating, high chemical resistance
Polyamide 6 and Tough and easy to mould, high temperature
polyamide 66 resistance
Polycarbonate Much better properties than with carbon black
Polycarbonate/ Very good toughness and good mouldability
acrylonitrile-butadiene-
styrene
Polycarbonate/ Very good toughness for housings
polybutylene
terephthalate
Glass-filled poly-p- Very high stiffness and very high temperature
phenylene sulfide resistance
Thermoset polyurethane Very large mouldings
The materials developed are targeted at standard injection-moulded articles. They give
a significantly better balance of mechanical and electrical properties than the current
generation of commercially available ESD protection and EMI shielding compounds.
With the best EMI shielding compounds developed in PolyCond, it should be possible
to use them in applications where they will replace mouldings with conductive coatings
and those that comprise materials with high loadings of conductive fillers.
The materials developed will allow the small- and medium-sized enterprises sector
to expand their product ranges into new applications by offering materials with an
expanded range of physical and electrical properties.
Several case studies focusing on new applications for the materials developed by the
PolyCond project have been produced. These are available on the project website.
Project Website:www.polycond.eu
xiii
An Introduction to Conductive Polymer Composites
Potential applications for PolyCond materials
xiv
C
ontents
1 Conductive Plastic Materials.......................................................1
1.1 General Introduction.........................................................1
1.1.1 General Information about Conductive Plastics......1
1.1.2 Intrinsically Conducting Polymers .........................2
1.1.3 Structures of Various Conductive Polymers ...........3
1.1.4 Carbon Nanotubes.................................................4
1.1.5 Carbon Nanotubes – Polymer Nanocomposites.....4
1.2 Processing of Conductive Plastic Materials........................8
1.2.1 Compounding........................................................9
1.2.2 Compounding Equipment....................................12
1.2.3 Mixing Factors.....................................................13
1.2.4 Formulations........................................................13
1.3 Benefits of using Plastic Conductive Materials.................15
1.3.1 Good Electrical Properties for a Broad Range
of Applications.....................................................15
1.3.2 Customisable Materials, Matching the
Desired Properties, Price Adjusting.......................15
1.3.3 Weight Reduction.................................................16
1.3.4 Ease of Processing ...............................................17
1.3.5 Applicable to Any Polymer...................................17
1.4 Applications ....................................................................18
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An Introduction to Conductive Polymer Composites
2 Conductive Materials................................................................23
2.1 Conductive Materials to Protect Against Unwanted
Electromagnetic and Electric Phenomena ........................23
2.2 Conductive Polymer Composites.....................................24
2.3 Carbon Nanotubes as Conductive Filler Materials ..........26
2.3.1 Compatibility of Carbon Nanotubes
with Polymers ......................................................26
2.3.2 Conductivity and Shielding Properties..................28
2.3.3 Mechanical Properties..........................................29
2.4 Polyaniline as Conductive Filler Material ........................31
2.5 Combinations of Carbon Nanotubes and Polyaniline
as Conductive Filler Materials.........................................31
2.6 Conclusions.....................................................................32
3 Testing of Conductive Materials................................................33
3.1 Introduction ....................................................................33
3.2 Electrical Conductivity ....................................................33
3.2.1 In-plane Conductivity...........................................35
3.2.2 Through-plane Conductivity................................36
3.2.3 The Van der Pauw Method...................................38
3.2.4 Dielectric Properties and Alternating
Current Conductivity...........................................39
3.2.5 Conductivity Measurements: Additional
Comments............................................................41
3.3 Methods to Measure Shielding Efficiency ........................41
3.3.1 Only a Few Words about the Physics …...............42
3.3.2 Reflection.............................................................42
3.3.3 Absorption...........................................................44
3.3.4 Multiple Reflection...............................................44
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Contents
3.3.5 Skin Depth...........................................................45
3.3.6 Near Field and Far Field.......................................45
3.4 Methods for Testing Shielding Efficiency.........................46
3.4.1 Shielded Box .......................................................47
3.4.2 Coaxial Transmission Line...................................47
4 Processing of Conductive Polymer Composites..........................49
4.1 Introduction ....................................................................49
4.1.1 Injection Moulding of Conductive
Thermoplastic Polymers.......................................49
4.1.2 Materials .............................................................49
4.1.3 Methods...............................................................50
4.2 Drying and Melt Temperature ........................................50
4.3 The Influence of the Mould Temperature ........................51
4.4 The Influence of the Injection Speed ................................54
4.5 The Influence of the Part Thickness and the
Distance from the Gate....................................................57
4.6 The Influence of the Surface Texture and
Flow Direction.................................................................61
4.7 Observations on Surface Appearance and
Microscopic Morphology ...............................................63
4.8 Conclusions.....................................................................67
5 Part Design using Conductive Materials....................................69
5.1 General Design Guidelines for Parts ................................69
5.1.1 Draft Angle..........................................................71
5.1.2 Wall Thickness.....................................................73
5.1.3 Bosses...................................................................74
5.1.4 Holes....................................................................74
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An Introduction to Conductive Polymer Composites
5.1.5 Threads................................................................76
5.1.5.1 External Threads...................................77
5.1.5.2 Internal Threads....................................78
5.1.5.3 Stripped Threads...................................78
5.1.6 Ribs......................................................................79
5.1.7 Radii and Corners................................................80
5.1.8 Oversized Areas ...................................................80
5.1.9 Undercuts.............................................................82
5.1.10 Gussets.................................................................83
5.1.11 Considerations Relating to Shrinkage and
Warpage...............................................................85
5.2 General Guidelines for Mould Design..............................86
5.2.1 Sprue Puller/Cold Material Trap...........................86
5.2.2 Main Runner........................................................86
5.2.3 Runner Design .....................................................86
5.3 Part and Mould Design using Conductive
Compounds for EMI and ESD Applications....................89
6 Applications of Conductive Plastics...........................................91
6.1 Introduction ...................................................................91
6.2 Current Applications and Market Size.............................94
6.3 Potential Future Applications and Market Size................95
6.4 Benchmarking Conductive Polymer Materials
with Competitors.............................................................98
6.4.1 Static Control.......................................................98
6.4.2 Electromagnetic Interference Shielding...............100
6.4.2.1 Compounding Solutions......................100
6.4.2.2 Another Competitor: Coatings............100
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