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Video: Novel, Bio-based Adhesive With Shape Memory
2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-05-24 11:12
Scientists from the Leibniz Institute for Catalysis, or Likat for short, succeeded in producing a polymer with joining and memory functions from the waste from wood and paper production. Researchers at the adhesive manufacturer Henkel are currently investigating to what extent the bio-based material can serve as an adhesive for industry. The work is part of the EU project "GreenSolRes", which researches the use of renewable raw materials for the production of biochemicals.
Bio-based instead of oil and natural gas
The long-term goal of "GreenSolRes" is the conversion of chemical processes from petroleum and natural gas-based processes to renewable resources. The experts assume that there are about a dozen so-called platform chemicals, which can be produced bio-based and are therefore suitable to replace petrochemicals. This includes levulinic acid. It is produced in high yield if, for example, wood waste is heated to 200 degrees with water and dilute sulfuric acid. This chemical reaction has been known for a hundred years.
The catalytic process for this was developed by Likat chemist Bernhard Stadler as part of his dissertation. The chemist refines derivatives of levulinic acid into innovative materials - this is achieved using catalysts and, in addition to levulinic acid, hydrogen and crosslinking agents. The end product is a clear, viscous liquid that can be used as an adhesive. When cured, the material behaves like a rubber.
Shape memory up to nine degrees
The polymer has a shape memory. It can be rolled up and keeps this shape below nine degrees Celsius. As soon as it warms up to room temperature, it unrolls into its original shape. Shape memory polymers are known, but the effect can be seen at very specific temperatures, often between 60 and 70 ° C.
With these effects, however, it is desirable to set switching temperatures as flexibly as possible - depending on the use, for example, in the range of body temperature or typical cooling temperatures. This results in application potential in medicine and logistics for the cooling of goods. Since it is possible to set different switching temperatures with bio-based 1,4-pentanediol in polymers, 1,4-pentanediol could become a central bio-based building block.
Chemist Bernhard Stadler
The adhesive based on levulinic acid is the result of close cooperation with the development department at Henkel. Both partners have registered a joint patent for the material and the process. Henkel is already producing the product on a kilogram scale for sample purposes.
“GreenSolRes” has been running since 2017 until the end of 2020, is funded with 7.45 million euros and unites six partners from industry and science in four countries. This international consortium is coordinated by RWTH Aachen. In addition, a plant for the production of levulinic acid is being optimized at RWTH Aachen University in cooperation with industrial partners. The Aacheners also take on the lifecycle assessment. Because the “green process” should be based as completely as possible on renewable raw materials. In fact, that is not yet the case, says Bernhard Stadler, but in principle it is possible.