Page 54 - Plastics News February 2019

teChnoLogy

Researchers develop fire-retardant coating featuring renewable

materials

exas A&M University researchers are developing a using a butane torch to determine the level of protection
Tnew kind of flame-retardant coating using renewable, the compounds provided. While uncoated polyurethane
nontoxic materials readily found in nature, which could foam immediately melts when exposed to flame, the
provide even more effective fire protection for several foam treated with the researchers' coating prevented
widely used materials.Dr. Jaime the fire from damaging any further than surface level,
Grunlan, the Linda & Ralph leaving the foam underneath undamaged."The nanobrick
Schmidt '68 Professor in the wall structure of the coating reduces the temperature
J. Mike Walker '66 Department experienced by the underlying foam, which delays
of Mechanical Engineering at combustion," Grunlan said. "This coating also serves to
Texas A&M, led the recently promote insulating char formation and reduces the release
published research that is of fumes that feed a fire.
featured on the cover of a
recent issue of the journal
Advanced Materials Interfaces. Upcycling plastic bags into
Successful development and
implementation of the coating battery parts
could provide better fire protection to materials including
upholstered furniture, textiles and insulation."These esearchers have reported a new method to convert
coatings offer the opportunity to reduce the flammability Rplastic bags into carbon chips that could be used
of the polyurethane foam used in a variety of furniture as anodes for lithium-ion batteries. They report their
throughout most people's homes," Grunlan noted. results in ACS Omega Many plastic bags are used only
once and then disposed, ending up in landfills, oceans
The project is a result of an ongoing collaboration between and elsewhere in the environment, where they can take
Grunlan and a group of researchers at KTH Royal Institute hundreds of years to decompose. Scientists have long
of Technology in Stockholm, Sweden, led by Lars Wagberg. recognized that the polyethylene in plastic bags could
The group, which specializes in utilizing nanocellulose, be an inexpensive source of energy-storing carbon.
provided Grunlan with the ingredients he needed to However, previous methods to upcycle polyethylene
complement his water-based coating procedure. In into pure carbon have been inefficient or required
nature, both the cellulose -- a component of wood and expensive, complex processes.
various sea creatures -- and clay -- a component in soil
and rock formations -- act as mechanical reinforcements Vilas Pol and colleagues wanted to develop a simpler
for the structures in which they are found."The uniqueness yet efficient approach to convert plastic waste into
useful carbon-containing materials. The researchers
in this current study lies in the use of two naturally immersed polyethylene plastic bags in sulfuric acid
occurring nanomaterials, clay nanoplatelets and cellulose and sealed them inside a solvothermal reactor, which
nanofibrils," Grunlan said. "To the best of our knowledge, heated the sample to just below polyethylene's melting
these ingredients have never been used to make a heat temperature. This treatment caused sulfonic acid
shielding or flame-retardant coating as a multilayer thin groups to be added to the polyethylene carbon-carbon
film deposited from water."Among the benefits gained from backbone so that the plastic could be heated to a much
using this method include the coating's ability to create an higher temperature without vaporizing into hazardous
excellent oxygen barrier to plastic films -- commonly used gases. Then, they removed the sulfonated polyethylene
for food packaging -- and better fire protection at a lower from the reactor and heated it in a furnace in an inert
cost than other, more toxic ingredients traditionally used atmosphere to produce pure carbon. The team ground
flame-retardant treatments. To test the coatings, Grunlan the carbon into a black powder and used it to make
and his colleagues applied the flexible polyurethane foam anodes for lithium-ion batteries. The resulting batteries
-- often used in furniture cushions -- and exposed it to fire performed comparably to commercial batteries.

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