From chicken feathers to fire retardant

Chicken is a popular source of protein in most parts of the world and millions of chickens are produced each year for us to eat – in New Zealand it’s estimated we each eat, on average, about 40 chickens a year.

Billions of chicken feathers are produced by the poultry industry, most of which end up in the incinerator or landfill. Chicken feathers are, in short, an international waste problem.

However, Distinguished Professor Debes Bhattacharyya of the Faculty of Engineering has found a way to use chicken feathers as a base for a fire-retardant, one that is safer than many fire-retardants, cheaper to produce, and solves an international waste problem at the same time.

“People pay to get rid of chicken feathers,” he says.

Chicken feathers are made of keritanous fibres which are found in the hair, wool, horns and hooves of mammals. They are also naturally occurring flame inhibitors.

Fire retardants are added to industrial and consumer products such as furniture, textiles, electronics, even Christmas trees, as well as building products such as insulation.

Traditionally halogen compounds were added to create flame retardant material, but while they were effective they were highly toxic. “They might have saved you from death by burning, but have exposed to many more effects that are detrimental to health.
 

“Furthermore, as a result of the environmental long life and bioaccumulation, traces of the compounds have been detected in everything from household dust to breast milk, causing hormone-disrupting effects." 

As a result there has been a global shift away from halogenic retardants and toward other types of retardants among which ammonium polyphosphate (APP) is the most prominent. However, as they are expensive to produce there is an increasing demand for alternatives.

Dr Bhattacharayya and his team have previously shown that chemically modified wool fibres also made of keratin can also be used as an effective retardant. This could potentially provide a revenue stream for low-grade wool in an era when the price of and demand for wool have declined.

They more recently turned to chicken feathers as an alternative source of keritanous fibres, which are even cheaper and in many countries, more of a waste problem.

The team has developed a rapid and simple way to chemically modify the keratinous fibres of both wool and chicken feathers, and convert them into a flame retardant powder that can be added to polymeric materials.

The powder enhances the fire retardancy of the polymer by accelerating char formation, the solid material produced in the initial stages of combustion, and which inhibits combustion.

Moreover, standard fire retardants need to be added in high concentrations which can reduce strength as a result, “but what we’re showing is that we can optimise the process so that this fire retardant removes this disadvantage of inferior mechanical performance compared to current fire retardants,” says Dr Bhattacharyya.

“We also assessed this from a commercial perspective and have been able to show that the cost around this compound is around a third lower than the existing standard compounds used as a fire retardant.

“So it’s a perfect fire retardant material, passes most of the fire retardant standards, and can be used with polymeric materials.”

He acknowledges that the method has so far been proven in the lab and getting it to market will require getting companies on board to develop ways to produce the keratinous fibre-based product at a large scale, and to ensure that it is compatible with existing manufacturing processes.

“However, initial results are very promising and has attracted the interests of several multi-national companies.

“Our invention, whose intellectual property rights are protected, has been tested to show that it could be a direct replacement for APP, the predominant existing product.”