Researcher Unveils Way to Develop Fire-resistant Cellulose-based Polymers

A team of researchers from Montana State University 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.

Cellulose: The Building Blocks for Chemical Technologies

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.
Because the particles are so tiny, 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.

Nanocrystals for Fire-safety and Light-weighting

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 make it stronger.

But the cellulose crystals' nano size, combined with their polar charge like static electricity, makes them difficult to mix into the plastic. By their nature, they want to clump up instead of dispersing into the plastic.

Overcoming that is a focus of his research under the new NIST grant, which builds on research being funded by 149,000 USD from the U.S. Department of Agriculture's National Institute of Food and Agriculture.

New Kinds of Mechanical Mixers Being Tested

Dilpreet Bajwa, professor at MSU's Norm Asbjornson College of Engineering, 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 in his lab. 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.

Plans for Future Commercialization

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. We have proven the concept and now we will be working on how to move it toward commercialization," said Bajwa.

Source: Montana State University