VATIS UPDATE Article

Researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL), the United States, have developed a recyclable thermoplastic that is significantly stronger than ABS (acrylonitrile, butadiene and styrene) by replacing styrene with lignin, a brittle, rigid polymer that, with cellulose, forms the woody cell walls of plants. The material, which its inventors call ‘ABL’, could prove to be a more sustainable alternative for use in ventilation pipes, protective headgear, kitchen appliances and many other consumer products that are currently fabricated from ABS.

“The new ORNL thermoplastic has better performance than commodity plastics like ABS,” said Amit Naskar, of ORNL, who together with co-inventor Chau Tran has filed a patent application for the process to make the new material. To produce an energy-efficient method of synthesizing and extruding high-performance thermoplastic elastomers based on lignin, the ORNL team needed to determine which types of lignin had both the thermal and melt stability to make them good candidates as a thermoplastic feedstock. The researchers then needed to “toughen” the lignin by chemically combining soft matter with it to make it more ductile.

Next, the researchers experimented to determine whether controlling the processing conditions could improve the performance of the polymer alloy. For example, 33% acrylonitrile content produced a material that was stretchy but not strong, behaving more like rubber than plastic. At higher proportions of acrylonitrile, the researchers saw the materials strengthen because of the efficient interaction between the components. They also wanted to know at what temperature the components should be mixed to optimize the material properties. They found heating components to between 140 and 160 degrees Celsius formed the desired hybrid phase.