FachPack 2019

•••6••• Innovationen Plastic made from crab shells and trees Researchers at Georgia Institute of Technology have developed new material for exible packaging R esearchers at Georgia Insti- tute of Technology have cre- ated a material derived from crab shells and tree fibres that has the potential to replace the flexible plastic packaging used to keep food fresh. The material is made by spraying multiple layers of chi- tin from crab shells and cellulose from trees to form a flexible film similar to plastic packaging film. “The main benchmark that we compare it to is PET, or polyeth- ylene terephthalate, one of the most common petroleum-based materials in the transparent pack- aging you see in vending ma- chines and soft drink bottles,” said J. Carson Meredith, a profes- sor in Georgia Tech’s School of Chemical and Biomolecular Engi- neering. “Our material showed up to a 67 per cent reduction in oxygen permeability over some forms of PET, which means it could in theory keep foods fresh- er longer.” Cellulose, which comes from plants, is the planet’s most com- mon natural biopolymer, followed next by chitin, which is found in shellfish, insects and fungi. The team devised a method to cre- ate a film by suspending cellulose and chitin nanofibres in water and spraying them onto a sur- face in alternating layers. Once fully dried, the material is flexible, strong, transparent and com- postable. “We had been looking at cellulose nanocrystals for several years and exploring ways to improve those for use in lightweight compos- ites as well as food packaging, because of the huge market op- portunity for renewable and com- postable packaging, and how im- portant food packaging overall is going to be as the population con- tinues to grow,” Meredith said. The research team also included scientists from other Georgia Tech schools. The team had been looking into chitin for an unrelat- ed reason when they wondered if it might have use in food packag- ing. “We recognised that because the chitin nanofibres are positive- ly charged, and the cellulose na- nocrystals are negatively charged, they might work well as alternat- ing layers in coatings because they would form a nice interface between them,” Meredith said. Packaging meant to preserve food needs to prevent oxygen from passing through. Part of the reason the newmaterial improves upon conventional plastic packag- ing as a gas barrier is because of the crystalline structure of the film. “It’s difficult for a gas molecule to penetrate a solid crystal, because it has to disrupt the crystal struc- ture,” Meredith said. “Something like PET on the other hand has a significant amount of amorphous or non-crystalline content, so there are more paths easier for a small gas molecule to find its way through.” Prof. J. Carson Meredith holds the new packaging ma- terial made from crab shell-sourced chitin and cellulose sourced from tree fibres. Photo: Allison Carter, Georgia Tech Etiketten mit Naturkleber Haftschmelzklebstoff auf Basis nachwachsender Rohstoffe Post-its, Klebebänder und Etiketten: Auch nach mehrfachem Anheften und rück- standslosem Wiederabziehen verlieren sie nicht ihre Klebkraft. Das liegt an den dabei verwendeten Haftklebstoffen, die in der Regel auf fossilen Rohstoffen basieren. For- scher von Fraunhofer UMSICHT haben ge- meinsam mit Partnern aus Wissenschaft und Industrie einen neuen Haftschmelz- klebstoff auf Pflanzenbasis entwickelt. Das Verbundvorhaben „BioPSA“ beschäf- tigte sich mit der Weiterentwicklung von Haftschmelzklebstoffen aus nachwachsen- den Rohstoffen, die zum Beispiel bei Klebe- bändern zum Einsatz kommen können. Das Ergebnis des Projekts, an dem die Westfä- lische Hochschule Recklinghausen sowie Industrie-Partner beteiligt sind: ein bioba- sierter Haftschmelzklebstoff, der sich auch in großemMaßstab produzieren lässt. Haftklebstoffe bestehen im Wesentli- chen aus drei Basis-Komponenten: Rück- gratpolymer, Klebrigmacher (Tackifier), Weichmacher. Rückgratpolymere – auch Basispolymere genannt – sind für den Zu- sammenhalt der gesamten Formulierung und für die Klebkraft verantwortlich. Sie geben den Klebstoffen also ihre innere Festigkeit (Kohäsion). Für die Herstellung von Haftklebstoffen aus nachwachsenden Rohstoffen ist die Wahl des Rückgratpo- lymers von großer Bedeutung. Unter dem Aspekt der Verfügbarkeit, der Kosten, der Modifizierungsmöglichkeiten, der Nachhal- tigkeit und der Verträglichkeit mit Träger- substraten ist die Wahl im Projekt „BioP- SA“ auf Poly-L-Milchsäure (PLA) gefallen. Dieses Polymer aus nachwachsenden Roh- stoffen ist im World-Scale-Maßstab und zu vergleichbaren Preisen wie fossilbasierte Rückgratpolymere verfügbar. Die Forscher von Fraunhofer UMSICHT haben die Eigen- schaften eines PLA-Rückgratpolymers so weiterentwickelt, dass sich die Formulie- rung vom Labormaßstab in die industrielle Praxis übertragen lässt. Mögliches Einsatzgebiet des neuen Bio- Haftklebstoffs: Klebeband Foto: Fraunhofer UMSICHT Novel ketchup packets Slippery packaging aims to cut food waste Almost everyone who eats fast food is familiar with the frustra- tion of trying to squeeze every last drop of ketchup out of the small packets that accompany french fries. That food left behind in plastic packaging also contrib- utes to the millions of pounds of perfectly edible food that Ameri- cans throw out every year. These small, incremental amounts of sticky foods like condiments, dairy products, beverages, and some meat products that remain trapped in their packaging can add up to big numbers over time. New research from Virginia Tech aims to cut down on that waste – and consumer frustration – with a novel approach to creating super slippery industrial packaging. The study establishes a method for wicking chemically compatible vegetable oils into the surfaces of common extruded plastics. Not only will the technique help sticky foods release from their packag- ing much more easily, but for the first time, it can also be applied to inexpensive and readily available plastics such as polyethylene and polypropylene. These hydrocarbon-based poly- mers make up 55 per cent of the total demand for plastics in the world today, meaning poten- tial applications for the research stretch far beyond just ketchup packets. They’re also among the easiest plastics to recycle. „Pre- vious SLIPS, or slippery liquid-in- fused porous surfaces, have been made using silicon- or fluorine- based polymers, which are very expensive,” said Ranit Mukherjee, a doctoral student in the Depart- ment of Biomedical Engineering and Mechanics. „But we can make our SLIPS out of these hydrocar- bon-based polymers, which are widely applicable to everyday packaged products.“ The researchers don’t work with nanoparticles, said Jonathan Boreyko, assistant professor of biomedical engineering and me- chanics. “We use natural oils like cottonseed oil, so there are no health concerns whatsoever.” While the method has obvious im- plications for industrial food and product packaging, it could also find widespread use in the phar- maceutical industry.