NTU Coating Protects Wood from Burning
FRIDAY, AUGUST 26, 2022
Scientists from Nanyang Technological University in Singapore have recently invented a clear fireproof coating designed to protect wood surfaces and materials.
“Mass engineered timber-based buildings – that’s one of the key applications that we’re looking at,” said associate professor Aravind Dasari, who led the research. “There’s huge potential in other areas, like for instance…steel.
“Although we have not completely explored this coating for steel, that could potentially be explored. Internal applications – lining materials, polymers. We can also coat this with polymers. So, the potential is there, it just has to be explored.”
According to NTU, the need for the coating became more prominent in recent years as developers and architects have adopted the use of mass-engineered timber for projects. However, the only downfall to using the material is that if left untreated, wood or timber can burn and combust easily.
Currently, there are practices in the industry to protect the interior of wooden buildings from fires using fire-retardant panels or paint-like coatings that conceal the natural wood grains of timber.
In comparison, the coating developed by NTU allows for the natural beauty of timber to shine and yet still provide a flame barrier when “activated” by fire.
When heated to 300 degrees Celsius (572 degrees Fahrenheit), the resinous coating (which is only about 0.075 mm thick) expands into a black char by more than 80 times its original thickness. The charred coating is heat resistant and acts as an insulating film, preventing the laminated wood from burning and thus preventing the spreading of flames.
According to the university, the coating is low-cost, easy to apply and effective in curbing the spread of fire.
When a flame is present against the surface, researchers note that there is very little smoke generated.
The innovation has a technology disclosure filed through NTUitive, NTU’s innovation and enterprise company. The commercialization project was funded S$250,000 through the NTUitive Gap Fund.
The NTU team is now in licensing talks with different companies. Venturer Timberwork is actively exploring the usage of this innovative coating to protect their mass-engineered timber elements in one of their current projects.
Other Recent Research
A reportedly non-toxic, fire extinguishing coating was developed by researchers from the University of Southern Queensland in Toowoomba, Australia, in January.
Inspired by one of the Earth’s hottest substances, molten lava, the hybrid coating aims to save buildings from being completely engulfed in flames. The research efforts for the development were led by USQ chemical engineer and Australian Research Council Future Fellow, Professor Pingan Song.
In making this observation about the natural substance, Song sought out to create a coating that could melt and then gradually form a flowing but non-combustible ceramic layer when exposed to extreme heat. This ceramic layer would then be able to better protect the underlying substrates, similar to a fire shield.
If these types of structures and select building materials were sprayed with a coating like his team developed, or thermal insulation foams, Song suggests that many of these types of tragedies could be prevented. However, most fire retardants in the market today are not effective enough, costly and sometimes are difficult to produce, USQ reports.
In an effort to mitigate the current shortcomings in the fire retardant coatings, Song and his team worked on a solution that would offer better protection and could even be used in additional application settings, such as on wooden furniture, mining, tunnels and various transportations.
While the coating is scheduled for additional testing and refinement before it can be commercialized, Song predicts that the coating could be available within the next three years.
Some months later, in March, a team of researchers presented a new type of coating that could limit the flammability of wood used in construction at the spring meeting of the American Chemical Society.
Department of mechanical engineering professor Jaime Grunlan led the research (partnered with researchers at KTH Royal Institute of Technology in Stockholm, Sweden, led by Lars Wagberg), and several years later, was joined by Thomas Kolibaba, Ph.D.
Noted to be an environmentally friendly flame retardant, the team envisions that the coating could also be utilized for other flammable materials, such as textiles, polyurethane foam and 3D-printed parts.
Typically, these types of environmentally friendly flame retardant coatings are created by dipping the desired material in a solution containing one polymer with positive charges on it, followed by a dip in another solution containing a polymer with negative charges. The steps are then repeated until a desired film thickness is achieved.
Through this method, opposing charges draw the polyelectrolyte molecules in the alternating layers together into complexes on the item’s surface, forming a coating that can extinguish a flame. However, a problem that Kolibaba found with this method was that it wasn’t feasible for wood materials because it takes too long to soak up the chemicals.
In continuing his research, Kolibaba adapted a preexisting Grunlan technique, which cut the number of steps down to two: one dip to coat the wood, followed by a dip in a different solution to cure the coating by changing the pH. However, that option still proved problematic in that the resulting material was sticky and remained inconvenient for industrial or consumer applications.
After additional modifications, Kolibaba developed a new method that involved dipping the plywood in an aqueous solution containing the positively charged polymer polyethylenimine (PEI), the monomer hydroxyethyl methacrylate phosphate (HMP) and a photoinitiator known as TPO. Then, instead of dipping the wood in a second solution, it was exposed it to ultraviolet light, causing the TPO to turn the HMP into a negatively charged polymer, which then formed a polyelectrolyte complex with PEI.
As a result, a transparent coating was left on the wood surface only a few micrometers thick. In testing the material, the treated wood reportedly lowered the amount of heat released during burning and quickly formed a surface layer of char that protected the underlying wood.
The researchers acknowledge support and funding from Texas A&M.
Tagged categories: Coating Materials; Coating Materials - Commercial; Coatings Technology; Colleges and Universities; Fire; Fireproofing; Fire-resistive coatings; Passive Fire Protection; Research; Research and development; Wood; Wood coatings; Wood graining
