Tag Archives: flame retardant materials

Lightweight nanomaterial for firefighters’ safety suits

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This piece of research on firefighters’ safety suits comes from Australia’s Nuclear Science and Technology Organisation (ANSTO). A February 3, 2022 article by Judy Skatssoon for governmentnews.com.au describes the work, (Note: Despite the date of the article, the research is from 2021)

Researchers at ANSTO are developing a new highly protective nano-material they believe will produce light-weight safety suits that are perfect for Australian firefighters.

The technology involves the use of super-thin nanosheets made from a new fire and heat-resistant non-organic compound, thermo-hydraulics specialist Professor Guan Heng Yeoh says.

The compound is created from titanium carbide and produces a lightweight coating which can be used in place of traditional fire protection measures. 

A compound extracted from prawn shells, chitosan, is used to bind the nanomaterial together.

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I found more details about the work in a January 25, 2022 ANSTO press release, Note: Links have been removed,

Scientists from UNSW [University of New South Wales] and ANSTO have characterised the structure of advanced materials, that could be used as a lightweight fire-retardant filler.

Fire retardant materials can self-extinguish if they ignite. 

A team under Professor Guan Heng Yeoh, Director of the ARC Training Centre for Fire Retardant Materials and Safety Technologies at UNSW and Thermal-Hydraulic Specialist at ANSTO, are working to commercialise advanced products for bushfire fighting, building protection and other applications.    

They investigated a family of two-dimensional transition metal carbides, carbonites and nitrides, known as MXenes.

In research published in Composites Part C, they reported the molecular structure of MXene, using neutron scattering and other advanced techniques.

Because the stability, properties, and various applications of MXene rely heavily on its atomic and molecular structure,  Prof Yeoh and associates conducted a detailed structural and surface characterisation of MXene.

Knowledge from this research provided good insight on how structure affects electrical, thermoelectric, magnetic and other properties of Mxene.

Experiments at ANSTO’s Australian Centre for Neutron Scattering on the Bilby small-angle neutron scattering (SANS) instrument were undertaken to characterise the two-dimensional structure of nanosheets—revealing the thickness of the material and the gaps between layers.

Theoretical modelling was used to extrapolate key information from the SANS data regarding the structural architecture of the titanium carbide nanosheets and investigate the influence of temperature on the structure.

Measurements revealed that MXene that is suspended in a colloidal solution consists of nanosheets of ultrathin multilayers with clear sharp edges.

The material comprises nanolayers, which overlap each other and form clusters of micro-sized units that endow a level of protection.

The nanolayers can be added on top of organic fire-retardant polymers. The total thickness of MXene was found to be 3 nm.

The information was in alignment with observations made using scanning electron microscopy and transmission electron microscopy.

Senior Instrument scientist Dr Jitendra Mata said, “Using SANS is like looking through a keyhole, the keyhole gives you a size indication from 1 nanometre to 500nm.  It may feel like a small size, but it’s actually not – many physical phenomena and the chemical structure occur within that size range.

“There are not many techniques in the world that gives you information about the structure and surface that accurately in a suspension and in films. Also, neutrons are ideal for many in-situ studies.”

Protective suits made with traditional retardant use as much as 30 to 40 per cent carbon compounds to achieve fire-retardant properties, which makes them heavy.

“Because we can use very low concentrations of the two-dimensional material, it comprises only about 1- 5 per cent of the total weight of the final material,” explained Prof Yeoh.

“And because it can be applied as a post-treatment, it doesn’t complicate the manufacturing process.”

When heat comes from above the surface of the material, it is conducted and moved along the nanosheets dispersing it. The nanosheets also act as a heat shield.

“At this point, it takes a lot of time to etch out the aluminium, but there are groups working on upscaling the MXene production process,” said Prof Yeoh.

“We also need to look at the performance and characteristics of the material at higher temperatures up to 800°C,” he added.

At the macro level, early tests have found the material to be an effective fire retardant.

A large team of researchers from the UNSW and ANSTO contributed to the research including first authors, Anthony Chun Yin Yuen and Timothy Bo Yuan Chen and ANSTO instrument scientist, Dr Andrew Whitten.

The versatile material could also potentially be used in energy storage devices.

Here’s a link to and a citation for the paper,

Study of structure morphology and layer thickness of Ti3C2 MXene with Small-Angle Neutron Scattering (SANS) by Anthony Chun Yin Yuen, Timothy Bo Yuan Chen, Bo Lin, Wei Yang, Imrana I.Kabir, Ivan Miguel De Cachinho Cordeiro, Andrew E.Whitten, Jitendra Mata, Bin Yu, Hong-Dian Lu. Guan Heng Yeoh. Composites Part C: Open Access Volume 5, July 2021, 100155 https://doi.org/10.1016/j.jcomc.2021.100155

This paper is open access.

Nanotechnology-enabled flame retardant coating

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This is a pretty remarkable demonstration made more so when you find out the flame retardant is naturally derived and nontoxic. From an Oct. 5, 2015 news item on Nanowerk,

Inspired by a naturally occurring material found in marine mussels, researchers at The University of Texas at Austin have created a new flame retardant to replace commercial additives that are often toxic and can accumulate over time in the environment and living animals, including humans.

An Oct. 5, 2015 University of Texas news release, which originated the news item, describes the situation with regard to standard flame retardants and what makes this new flame retardant technology so compelling,

Flame retardants are added to foams found in mattresses, sofas, car upholstery and many other consumer products. Once incorporated into foam, these chemicals can migrate out of the products over time, releasing toxic substances into the air and environment. Throughout the United States, there is pressure on state legislatures to ban flame retardants, especially those containing brominated compounds (BRFs), a mix of human-made chemicals thought to pose a risk to public health.

A team led by Cockrell School of Engineering associate professor Christopher Ellison found that a synthetic coating of polydopamine — derived from the natural compound dopamine — can be used as a highly effective, water-applied flame retardant for polyurethane foam. Dopamine is a chemical compound found in humans and animals that helps in the transmission of signals in the brain and other vital areas. The researchers believe their dopamine-based nanocoating could be used in lieu of conventional flame retardants.

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“Since polydopamine is natural and already present in animals, this question of toxicity immediately goes away,” Ellison said. “We believe polydopamine could cheaply and easily replace the flame retardants found in many of the products that we use every day, making these products safer for both children and adults.”

Using far less polydopamine by weight than typical of conventional flame retardant additives, the UT Austin team found that the polydopamine coating on foams leads to a 67 percent reduction in peak heat release rate, a measure of fire intensity and imminent danger to building occupants or firefighters. The polydopamine flame retardant’s ability to reduce the fire’s intensity is about 20 percent better than existing flame retardants commonly used today.

Researchers have studied the use of synthetic polydopamaine for a number of health-related applications, including cancer drug delivery and implantable biomedical devices. However, the UT Austin team is thought to be one of the first to pursue the use of polydopamine as a flame retardant. To the research team’s surprise, they did not have to change the structure of the polydopamine from its natural form to use it as a flame retardant. The polydopamine was coated onto the interior and exterior surfaces of the polyurethane foam by simply dipping it into a water solution of dopamine for several days.

Ellison said he and his team were drawn to polydopamine because of its ability to adhere to surfaces as demonstrated by marine mussels who use the compound to stick to virtually any surface, including Teflon, the material used in nonstick cookware. Polydopamine also contains a dihydroxy-ring structure linked with an amine group that can be used to scavenge or remove free radicals. Free radicals are produced during the fire cycle as a polymer degrades, and their removal is critical to stopping the fire from continuing to spread. Polydopamine also produces a protective coating called char, which blocks fire’s access to its fuel source — the polymer. The synergistic combination of both these processes makes polydopamine an attractive and powerful flame retardant.

Ellison and his team are now testing to see whether they can shorten the nanocoating treatment process or develop a more convenient application process.

“We believe this alternative to flame retardants can prove very useful to removing potential hazards from products that children and adults use every day,” Ellison said. “We weren’t expecting to find a flame retardant in nature, but it was a serendipitous discovery.”

Here’s a link to and a citation for the paper,

Bioinspired Catecholic Flame Retardant Nanocoating for Flexible Polyurethane Foams by Joon Hee Cho, Vivek Vasagar, Kadhiravan Shanmuganathan, Amanda R. Jones, Sergei Nazarenko, and Christopher J. Ellison. Chem. Mater., 2015, 27 (19), pp 6784–6790 DOI: 10.1021/acs.chemmater.5b03013
Publication Date (Web): September 9, 2015
Copyright © 2015 American Chemical Society

This paper is behind a paywall. It should be noted that researchers from the University of Southern Mississippi and the Council of Scientific & Industrial Research (CSIR)-National Chemical Laboratory in Pune, India were also involved in this work.