Polystyrene foam has many industrial applications due to its lightweight and thermal insulation properties, and it is used for a range of products from packaging to construction, as reported by thechemicalengineer.com.
However, it is petroleum-based, is composed of toxic styrene blocks, doesn’t biodegrade, and has poor fire resistance. Researchers at Washington State University, US, have developed an environmentally friendly plant-based polystyrene foam. Previous attempts to make plant-based foams have resulted in foams that weren’t as strong as their petroleum counterparts, didn’t insulate well, and degraded too easily. The team developed an environmentally-friendly process that used water as a solvent instead of other harmful solvents. The foam was created using nanocrystalline cellulose (NCC) which was extracted from wood pulp. Cellulose is the world’s most abundant organic polymer.
The new foam is a composite created from 75% NCC, along with polyvinyl alcohol (PVA), and 1,2,3,4–butane tetracarboxylic acid (BTCA). PVA is a non-toxic, water-soluble polymer that is used to increase the elasticity, and the BTCA was used as a crosslinking agent to bond the NCC and PVA. The resulting foam is a good insulator as it has a uniform cellular structure and even surpasses petroleum-based polystyrene foam as an insulator. It is lightweight but also has good mechanical strength, and the sample could withstand a load 200 times its weight without any shape distortion. It also has good fire resistance. "We have used an easy method to make high-performance, composite foams based on nanocrystalline cellulose with an excellent combination of thermal insulation capability and mechanical properties," said Amir Ameli, Assistant Professor at Washington’s School of Mechanical and Materials Engineering. "Our results demonstrate the potential of renewable materials, such as nanocellulose, for high-performance thermal insulation materials that can contribute to energy savings, less usage of petroleum-based materials, and reduction of adverse environmental impacts."
"This is a fundamental demonstration of the potential of nanocrystalline cellulose as an important industrial material," said Xiao Zhang, Associate Professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering. "This promising material has many desirable properties, and to be able to transfer these properties to a bulk scale for the first time through this engineered approach is very exciting." Future work will involve developing stronger and more durable materials, incorporating low-cost feedstocks, and scaling up the process.