Everytime we board a plane, we are taken through a detailed safety demonstration that reminds us how dangerous flying can be. One key issue that contributes to wear and tear on an aircraft is corrosion. Aircrafts are made of an aluminium alloy, which forms a non-protective oxide that is subject to corrosion. This corrosion can be expensive to remove, impact the aircrafts readiness and creates a safety hazard.
To prevent corrosion, chromate coatings have been used on aircrafts. However, these can also be problematic. These coatings have been found to be carcinogenic, causing long-term health issues when people are exposed over a period of time and have adverse environmental impacts.
Gunjan Gupta, a research scholar at IITB-Monash Research Academy in Mumbai, has been undertaking research on conducting polymer coatings
The IITB-Monash Research Academy is a Joint Venture between the IIT Bombay, India and Monash University, Australia. Opened in 2008, the IITB-Monash Research Academy operates a graduate research program located in Mumbai that aims at enhancing research collaborations between Australia and India. Students study for a dually-badged PhD from both institutions, and spend time during their research in both India and Australia.
Conducting polymer coatings are environmentally friendly coatings that are an appropriate substitute for heavy metal compounds. The conductive nature of these polymers provide an electroactive interaction with the metal surface and forms a passivation layer between the metal surface and the polymer coating, acting as a barrier coating as well. These coatings may also impact the internal components of the aircraft when exposed to lightening or ‘electrical thundering’.
Gupta’s research is looking at developing a conducting polymer coating using polyaniline, which provides adequate conductivity and protection against corrosion for aluminium allows and provides over 6 times more conductivity than other coatings. Polyaniline in particular has high environmental stability, is low cost and has a simple polymerisation process. When this is added to an epoxy resin – a binder with excellent adhesion, resistance to corrosion and good mechanical and thermal properties – it has been found that the properties of the epoxy resin are actually enhanced.
One of the issues with using polyaniline is its poor level of solubility that can impact its level of conductivity. One option is to use organic dopants, such as 10-camphorsulfonis acide (CSA), dodecylbenzenesulfonic acid (DBSA) and lignosulfonic acid (LGS) tha increases the solubility of the conducting polymer. As a result the conducting polymer can be easily dissolved or belnded with other polymers.
Gupta’s research is important as it not only will provide an environmentally friendly coating system for aircrafts, but it the polymer will also incorporate properties of organic dopants and nanoparticles in the coating. Whilst this coating has been designed specifically to be used in aircraft coatings, it also may have various other uses.
Gupta is very excited about the impact of her work. “My research will have a positive impact on the aviation industry and environment, helping to combat both the environmental and health issues associated with existing coatings without compromising the corrosion resistant and conductivity,” Gupta comments, and adds, “This project has given me the opportunity to be exposed to international expertise that has helped me think substantially differently.”
There are two other main applications for these conducting polymers. First, utilising it for its conductive property such as in electrostatic materials, conducting adhesives, printed circuit boards and active electronics (like transisitors). Secondly, it can also be used for its electroactivity in electrical displays, chemical , biochemcial and solid electrolytes, drug release systems, and “smart home” systems
As the extended p-systems in conjugated polymers are highly susceptible to chemical or electrochemical oxidation or reduction, these can alter the electrical and optical properties of the polymer and control the level of oxdation and reduction. As these proeprties can be precisely controlled, and reversed if necessary, then the electrical and optical properties can be controlled with a great deal of precision. It is even possible to switch from a conducting state to an insulating state with conducting polymers.
Soon, with the work of Gupta, we will be able to board an aircraft knowing that it is not only safe, but also more environmentally friendly.
Research scholar: Gunjan Gupta, IITB-Monash Research Academy
Project title: Development of corrosion resistant conducting polymer coatings for aircraft applications
Supervisors: Professor A S Khanna and Professor Nick Birbilis
Contact details: firstname.lastname@example.org
The above story was written by Ms Rakhee Ghelani based on inputs from the research student and IITB-Monash Research Academy.