|A clear adhesive tape. / Photo by: Tomasz Sienicki via Wikimedia Commons|
Adhesive tapes are used to attach one material to another or wrap gifts for special occasions. These adhesive tools are made of components derived from petroleum, a less sustainable natural resource than most. Thus, engineers at the University of Delaware looked for a better alternative for manufacturing adhesive tapes, and they found lignin as a potential solution.
Lignin is a class of complex organic polymers that support the tissues of many vascular plants and even some types of algae. It is a component typically thrown away by paper manufacturers. Most paper manufacturers do not dispose it in landfills, but choose to deliver dump trucks filled with lignin for free, provided another company would take them. The engineers saw this as an inexpensive and sustainable source for adhesive production. The method can also help in the recycling efforts of lignin.
To make an adhesive tape made of lignin, the team created a mild, low-temperature process called depolymerization that would break the hard plant material into small molecular fragments. Then, they adjusted certain attributes in the fragments through a series of processes to synthesize new materials. The new materials would have the same sticky properties demonstrated by adhesive tapes.
“We can use the same separation, purification, polymerization, and characterization methods to make these materials as one can use to make the current commercial, and petroleum-based, analogs. But we can get better properties, and we can use a much greener source,” explained Thomas H Epps, III, the corresponding author of the study and a professor of Materials Science and Engineering at UD.
After they produced the new materials from the processed fragments, the engineers tested the adhesive strength of the product. The mechanical tests showed that their tape performed equally as Fisherbrand labeling tape and Scotch Magic Tape.
The new method could aid paper producers economically by allowing them to sell lignin to adhesive manufacturers. It would also reduce the dependence of adhesive makers to petroleum-based components.