Environment Plants and Animals

Starch Used to Make Paper and Other Materials More Biodegradable and Water Resistant

Newly developed ARS, starch-based coating, makes paper water resistant. Image credit: Peggy Greb
Newly developed ARS, starch-based coating, makes paper water resistant. Image credit: Peggy Greb

Agricultural Research Service (ARS) scientists have developed a new coating or film based on starch. The coating makes paper and other materials more biodegradable and water resistant.

The coating could possibly be used in plastic bags, food packaging and other products. This could result in a reduction in the volume of synthetic waste that currently clog landfills. Starch is 100% biodegradable and is used in some films and plastics because it is cheap and biodegrades fast. Existing materials containing starch do however not have the flexibility, strength and ease of processing needed for many other uses.

Polyvinyl alcohol (PVOH) is a synthetic polymer that is petroleum based and it is widely used for film applications. Its biodegradability is however limited. Researchers at the ARS National Center for Agricultural Utilization Research (NCAUR) in Peoria, Illinois, recently developed starch complexes that can be mixed with PVOH to improve the properties of films and make them more biodegradable. Plant physiologist Frederick Felker, chemist George Fanta, research associate William Hay and chemist Gordon Selling were all members of the team.

Fanta noted that they continuously look for new value added products from starch that benefit consumers and U.S agriculture at their lab. Products that are developed can help replace synthetic products like polystyrene foam packing materials and plastic polyethylene bags totally.

The team produced the complexes from fatty amine salts and high amylose cornstarch, which are derived from soybean oil. These complexes have valuable and unique properties that not present in either ingredient on their own. The Journal of Applied Polymer Science recently published one aspect of this research.

Fanta added that the complexes could be mixed with PVOH in big quantities to make films with increased elasticity and good physical properties. They are also more resistant to water infiltration than films made from pure PVOH were.

Selling noted that some food packaging is made from only PVOH. He added that the performance of packaging should remain unchanged even with up to 60 percent of these starch complexes incorporated into them. Paper’s water resistance can be increased by applying the complexes in solution to it. Untreated paper absorbs a drop of water quickly. When paper is coated with these complexes, water on it beads up and remains on the surface for minutes. Depending on the formulation, the water often evaporates before soaking into the paper.

The new paper related technology can be commercialized readily and is ideal for use by small papermaking companies. ARS has filed a patent application for the technology.

Fanta concluded by saying that the process is inexpensive and the complexes are nontoxic and 100% bio based.