Researchers at the Georgia Institute of Technology in the USA have succeeded in developing a viable substitute to flexible plastic packaging. The new material is derived from crab shells and tree fibres. Like flexible plastics, the breakthrough material would prevent oxygen penetrating its surface, maintaining the freshness of food.The material is made by spraying multiple layers of chitin from crab shells and cellulose from trees to form a flexible film similar to plastic packaging film. Cellulose, the principle structural component of plants, is the worlds most common natural polymer, followed by chitin, a fibrous substance found in crab shells and the cell walls of fungi.
The main benchmark that we compare it to is PET, or polyethylene terephthalate, one of the most common petroleum-based materials in the transparent packaging you see in vending machines and soft drink bottles, said J. Carson Meredith, a professor in Georgia Techs School of Chemical and Biomolecular Engineering. Our material showed up to a 67 percent reduction in oxygen permeability over some forms of PET, which means it could in theory keep foods fresher longer.
The development process of the material involved the creation of a film by suspending cellulose and chitin nanofibers in water. Following this, the film is sprayed onto a surface in layers. This becomes flexible, strong, transparent and compostable after the layers have sufficiently dried.
The use of chitin in flexible bio-plastics was stumbled on by mistake. The team at the Georgia Institute of Technology had been investigating the compounds of chitin for an unconnected reason before querying its potential use in food packaging. Carson Meredith goes on to point out that chitin nanofibers are positively charged, and the cellulose nanocrystals are negatively charged (and so) might work well as alternating layers in coatings.
The phenomenon of exploring ways to replace petroleum-based products in consumer products is not new. Though, the derivations of flexible plastics from both cellulose and chitin together offers the bio-industry a pioneering new angle into which bio-based companies can invest resources. With the amount of cellulose already produced and a ready supply of chitin-rich by-products left over from the shellfish food industry, there are enough resources to manufacture a new, viable flexible-packaging alternative. Still, the development of the film remains in the research phase of development and Meredith points out that more needs to be done to improve the materials ability to block water vapour.
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