Shoes, cars, airplanes, rotor blades for wind turbines, self-adhesive notes, plasters – this is just a sample of the many products featuring adhesives. More than 820,000 tons of adhesive were produced in Germany in 2010, according to the German Adhesives Association – Industrieverband Klebstoffe.
This adhesive is based on the renewable raw material polylactic acid. © Heike Holthausen, Westfälische Hochschule, Recklinghausen
To this day the majority of adhesives are manufactured from petroleum-based materials. Only gradually is the industry also offering adhesives made from renewable raw materials such as starch, cellulose, dextrins, and proteins. Pioneering products featuring these new adhesives include wallpaper pastes and glue sticks.
Adhesive based on polylactic acid
In two projects, researchers at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT are working on further new adhesive formulas based on renewable raw materials. In cooperation with the Recklinghausen site of the Westfälische Hochschule, University of Applied Sciences, and the companies Jowat, Logo tape, and Novamelt, and with support from Germany’s Federal Ministry of Food, Agriculture and Consumer Protection, researchers at UMSICHT in Oberhausen are developing a pressure-sensitive adhesive for industrial applications. Products using pressure-sensitive adhesives include adhesive bandages, self-adhesive labels, and adhesive tapes.
They are subject to particularly demanding requirements: They have to remain permanently adhesive at room temperature. Gentle pressure should suffice for them to adhere to almost all substrates, and yet it must be possible to remove them without leaving behind any residue. To achieve this, the adhesive force must precisely match the respective use.
Pressure-sensitive adhesives are based on backbone polymers, which give the adhesives their inner strength (cohesion). The challenge for the UMSICHT researchers is to develop a backbone polymer from the raw material polylactic acid. What makes this biological material particularly attractive is its low production cost; since lactic acid is produced on an industrial scale, costs are in the region of prices for fossil-based backbone polymers.
“However, the properties of polylactic acid are completely different from those of the polymers used to date, such as polyacrylates and styrene-based block copolymers,” explains Dr. Stephan Kabasci, who heads the UMSICHT renewable resources business unit. This means that the researchers have to develop a completely new formula.
Packaging using compostable films
However, adhesives are also found in many types of packaging, for example where laminating films protect foodstuffs from dirt, moisture, and chemicals. This involves covering printed packaging and printed paper products on one or both sides with a transparent, shiny, matt, or embossed plastic film. In a collaborative project, UMSICHT scientists are working with the companies Achilles Papierveredelung Bielefeld, Jowat, and Deckert Management Consultants to develop innovative adhesive systems that meet the exacting quality requirements of laminated products as well as being compostable. In pursuit of this objective, the researchers are focusing primarily on water-based dispersion adhesives, in which the adhesive components are dispersed very finely in water. They are applied to one side of the product and joined while wet.
Nature shows us another path to developing biological adhesives. The buoy barnacle (Dosima fascicularis) produces a special adhesive which it uses to attach itself tightly to flotsam. This super-adhesive is so strong that it is almost impossible to break down into its constituent parts using ordinary solvents. Another special property it has is its ability to cure under water. Researchers at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Bremen are now trying to find out which amino acid components make up the relevant proteins. “Once we’ve done that, the next step will be to recreate the adhesive proteins in the laboratory,” says Dr. Ingo Grunwald, expert for biological adhesives at the IFAM. Such bioadhesives are primarily of interest for medical applications, for example to close incisions or to replace or support the pins and screws used to treat bone fractures.
Dr.-Ing. Stephan Kabasci | Fraunhofer Research News
Physics, photosynthesis and solar cells
01.12.2016 | University of California - Riverside
New process produces hydrogen at much lower temperature
01.12.2016 | Waseda University
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy