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Montana State University researcher Dilpreet Bajwa and his team backed by a new $220,000 grant from the National Institute of Standards and Technology, is developing methods to infuse polymers with particles called nanocrystals that are made from cellulose, a primary component of plants. Whereas many regular plastics can combust when subjected to fire or very intense heat, the nanoparticles are designed to limit the flames and prevent their spread.
Improving Conventional Fire-resistant Polymers
Scientists have known about cellulose nanocrystals for decades, but the particles' myriad applications are still being developed. By processing wood pulp of other plant matter using special chemical reactions, cellulose molecules become building blocks for chemical technologies that operate at the nano scale, which concerns things as small as one-billionth of a meter.
The particles are so tiny and a relatively small volume of them can be mixed throughout a much larger amount of polymer. When the particles are coated in zinc oxide, a common ingredient found in many sunscreens, the zinc oxide's fire-resistant properties are imparted to the plastic.
The resulting plastic is a major improvement over fire-resistant polymers currently on the market, which rely on particles of glass or earthen minerals like talc. Because those particles are much bigger, they constitute up to one-fifth of the mass of product, making it much heavier. Those additives also make the plastic brittle, whereas nanocrystals can actually make it stronger.
But the cellulose crystals' nano size, combined with their polar charge similar to static electricity, makes them difficult to mix into the plastic. "
By their nature, they want to clump up instead of dispersing into the plastic," Bajwa said. Overcoming that is a focus of his research under the new NIST grant, which builds on research being funded by $149,000 from the U.S. Department of Agriculture's National Institute of Food and Agriculture.
Mixing the Fire-resistant Particles into Plastic
In his lab, Bajwa will develop new kinds of mechanical mixers as well other treatments, such as zapping the nanocrystals with electrically charged gases, in order to mix the fire-resistant particles into plastic, he said. The goal is to develop methods that can be integrated with existing machinery used in industry to form plastic parts, so that the technology could easily be adopted by manufacturers.
Nicole Stark, research chemical engineer at the Forest Products Lab, will oversee fire testing of the plastics the team makes. Another partner on the project, Mohiuddin Quadir, assistant professor in the department of coatings and polymeric materials at North Dakota State University, will develop methods for effectively coating the nanoparticles.
While the primary application would be in the automotive industry, the nanocrystal-infused plastic could improve upon products such as home siding as well as a variety of durable consumer goods where fire-resistance is important. "
We think we'll be able to move this technology forward," Bajwa said.
Source: Montana State University