Adhesive tape made from lignin, a common waste product of paper manufacturing, performs just as well as at least two commercially available products.
Adhesives are often are made from petroleum-derived materials, so a more sustainable production method is certainly on the cards.
Researchers from the University of Delaware are hopeful they can make this happen. As lignin is an inexpensive, plentiful and sustainable material, it presents a prime opportunity for some scientifically advanced upcycling.
Lignin is a natural polymer and shares some structural and material property similarities with petroleum-derived polymers, such as polystyrene and polymethyl methacrylate, which are commonly used in adhesives and other consumer products.
The first step in the process was for lignin to be broken down by researchers at the Catalysis Center for Energy Innovation (CCEI), a multi-institutional research centre at the University of Delaware (UD).
Director of CCEI and the Delaware Energy Institute Dr Dionisios Vlachos and his team have been perfecting methods to break down some wood components (cellulose and hemicellulose) into useful products. However, lignin presented a tougher challenge.
“Lignin is very hard, a solid part of the biomass that is the hardest to break down,” said Dr Vlachos.
“Developing a catalyst and a process to actually crack these molecules is difficult.”
The team developed a mild, low-temperature process that broke the lignin into small, molecular fragments—a process called depolymerisation.
Dr Thomas Epps, Professor of Materials Science and Engineering at UD, then used those components to synthesise new materials, adjusting their properties for use in pressure-sensitive adhesives.
“We can use the same separation, purification, polymerisation, and characterisation methods to make these materials as one can use to make the current commercial petroleum-based analogues,” said Professor Epps. “But we can get better properties, and we use a much greener source.”
Using mechanical tests to determine adhesion and tackiness, the researchers found their tape performed well.
“We were expecting it to be competitive because we knew that if we could form well-defined polymers, we could engineer them to have similar performance,” said Epps.
“The thing that we found a bit surprising and interesting is that our materials gave similar performance to Scotch Tape and Fisherbrand tape without any additional formulation or other additives that are typically used in commercial materials to improve their performance.”
Many tapes have added tackifiers, substances that increase adhesion but can also decrease the lifetime of materials.
Dr Vlachos sees tremendous economic potential in the invention and the research team has filed for a provisional patent on this work.
Source: Phys Org or read original paper in ACS Central Science, 4(6): 662-780
