Polyaniline - Processing and Applications

Topics Covered

Background

Polyaniline

Advantages

Wide and Controllable Range of Conductivity

Melt and Solution Processable Material

Conductive Blends with Many Commodity Polymers

Function as Processing Aids in Addition to Providing Conductivity

Coloured and Transparent Electrically Conductive Products

Applications using Polyaniline Based Conductive Polymers

Neat Materials, Blends, Compounds and Solutions

Electrostatic Discharge (ESD) Protection Materials

Processing Techniques

Melt Processing

Solution Processing

Examples of Industries and Products

Packaging Industry

Electronics

Fenestration

Textile Industry

Automotive Industry

Construction

Mining

Tomorrow’s Applications

Products Tailored To Customer’s Needs

Future Possibilities

Background

One key property distinguishing classical polymers from metals is their low electrical conductivity. A new class of organic polymers capable of conducting electricity has recently been developed. These polymers become conductive upon partial oxidation or reduction, a process commonly referred to as doping. The electrical properties of conductive polymers can be reversibly changed over the full range of conductivity from insulators to metallic conductors.

During the past two decades, conductive polymers have been under intensive research and development in the academic world and also in the chemicals and electronics industry world-wide. Their use as new materials in value added industrial and consumer products is opening up entirely new dimensions for polymeric materials. The major drawback of existing conductive polymers has been their modest environmental stability and/or intractability, which made it difficult to process them into meaningful end products using conventional processing methods.

Polyaniline

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.

Advantages

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.

Processing Techniques

Melt Processing

         Injection moulding

         Extrusion & co-extrusion

         Blow moulding

         Calandering

         Fibre spinning

         Compression moulding

         Extrusion coating

Solution Processing

         Coating - films

         Spraying

         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:

Packaging Industry

         Injection moulded antistatic products

         Antistatic films

Electronics

         Antistatic packaging of components

         Printed circuit boards

Fenestration

         Electrochromic “smart” windows

         Electrochromic automobile rear vision systems

Textile Industry

         Conductive fabrics

Automotive Industry

         Antistatic charge dissipation

         Paint primers

         Electrochromic rear vision systems

Construction

         Antistatic floors

         Antistatic work surfaces

Mining

         Conductive pipes for explosives

         Antistatic packaging

Tomorrow’s Applications

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.

Future Possibilities

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.

 

Source: Panipol Ltd

 

For more information on this source please visit Panipol

 

Date Added: Jan 16, 2002 | Updated: Jun 11, 2013
Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit