The discovery of electrically conductive polymer compositions based on polyaniline provides conductive materials, which are soluble in selected organic solvents. These materials are which are melt processable and exhibit good ambient stability characteristics.
The major target of conductive polymer technology development has been to combine the electrical and optical properties of these new materials with the mechanical and processability properties of commodity bulk polymers. New conductive materials that offer significant application potential as substitutes, and new products having properties difficult or impossible to achieve by existing materials, can now be produced.
Some polyaniline based materials are solution and melt processable. They offer clear benefits over traditional plastics made conductive by the addition of fillers (carbon blacks, metal particles and flakes, metal fibres, carbon fibres, and others). They provide precisely controlled electrical conductivity over a wide range, improve phase compatibility and thus blendability with bulk polymers, provide easier means of processing and forming conductive products and provide low cost solutions for the production of transparent and coloured thin films and coatings.
Wide and Controllable Range of Conductivity
The electrical conductivity of polyaniline based compositions can be closely controlled over a wide range. For neat polyaniline compositions conductivity levels as high as 100 S/cm can be achieved. The full range of conductivity levels from less than 10-10 to 10-1 S/cm (melt processing) and 10 S/cm (solution processing), can be achieved for polymer blends containing polyaniline compositions. An important advantage is that the classical high percolation threshold for the onset of electrical conductivity observed in globular carbon black filled plastics, does not exist.
Melt and Solution Processable Material
Polyaniline based compositions can be processed using conventional techniques such as blow and injection moulding, extrusion, calendering, film casting, and fibre spinning. These compositions withstand temperatures as high as 230-240°C for short periods of time (5-10 minutes) without significant change in electrical properties, and can be melt blended with many commodity polymers. Selected industrial solvents can be used for solution processing neat polyaniline compositions.
Conductive Blends with Many Commodity Polymers
Electrically conductive polyaniline based blends with commodity polymers can be produced by using common solution and melt processing techniques. Examples of commodity polymers are polyethylene, polypropylene, polystyrene, PVC, phenol-formaldehyde resins, and different types of thermoplastic elastomers. Unlike conventional filled materials, the mechanical properties of these blends are close to those of the insulating matrix polymer.
Function as Processing Aids in Addition to Providing Conductivity
Plasticised polyaniline compositions improve melt processing performance by lowering the melt-viscosity, lowering the processing temperature and shortening the processing time. The improved melt flow properties make, for example injection moulding of complex shapes easier.
Coloured and Transparent Electrically Conductive Products
Electrically conductive, coloured and transparent thin films and coatings, which would otherwise be difficult to achieve with conventional filled materials, can be made using polyaniline based compositions.
Applications using Polyaniline Based Conductive Polymers
Neat Materials, Blends, Compounds and Solutions
Polyaniline based conductive polymers can be used neat, or as blends and compounds with commodity polymers. Several prototype objects and articles have been made of these compounds with polyethylene, polypropylene, polystyrene, soft PVC, poly-(methylmetacrylate), phenol-formaldehyde resins, melamineformaldehyde resins, epoxies, and thermoplastic elastomers.
The solution processing properties of polyaniline based conductive polymers make totally new product ideas possible. These include electroactive inks, paints, coatings, and adhesives, electrochromic “smart” windows, electrically conductive transparent films, and conductive high performance fibres. Solution processing can be carried out using the neat material or a blend.
Electrostatic Discharge (ESD) Protection Materials
One target application of these materials is the protection from ElectroStatic Discharge (ESD). ESD causes problems when handling sensitive electronic components, explosive chemicals or dry powders. The use of, e.g. antistatic materials in specific environments reduce ESD related problems, such as the amount of damaged valuable end products in an assembly line. The controllable conductivity in ESD protection materials is one of the basic benefits of conductive polymer technology.
• Injection moulding
• Extrusion & co-extrusion
• Blow moulding
• Fibre spinning
• Compression moulding
• Extrusion coating
• Coating - films
• Solution spinning - fibres
• Casting - films
• Spin coating -thin films
• Gels - high strength fibres and films
Examples of Industries and Products
Conductive polymers are attractive for new product concepts and for replacing conventional materials due to their unique combination of processability, stable and controllable conductivity, and optical and mechanical properties. There is a diversity of different industries and products where these compositions can be used:
• Injection moulded antistatic products
• Antistatic films
• Antistatic packaging of components
• Printed circuit boards
• Electrochromic “smart” windows
• Electrochromic automobile rear vision systems
• Conductive fabrics
• Antistatic charge dissipation
• Paint primers
• Electrochromic rear vision systems
• Antistatic floors
• Antistatic work surfaces
• Conductive pipes for explosives
• Antistatic packaging
Products Tailored to Customer’s Needs
The aim of manufacturers is to develop and market a new family of proprietary and high-quality conductive polymer materials that are superior to other materials, and exactly match customer needs. Close co-operation between all those involved is the key to success.
Polyaniline products can be tailored to your needs. These efforts are focussed on customers’ technical specifications, such as required conductivity, mechanical properties, processing conditions and operating conditions. Once the right property spectrum of these novel materials has been defined and specified, totally new applications and product concepts can be designed and developed into value added end products.
Most of the current development is focused on further developing polyaniline compounds for the existing applications, i.e. films, fibres and coatings. This will include development to achieve compatibility with new matrixes, binders and solvents.
As this technology further develops, there will be new applications and market segments emerge. These may include for example shielding of electronic equipment from Electro-Magnetic Interference (EMI) or conductive and semi-conductive cable jackets.