Nanoscience promises better battlefield rations.

Researchers at the U.S. Army Soldier Systems Center in Natick, Mass., are improving combat ration packaging by replacing the layers of aluminum foil with nanocomposite films to make the packaging more resilient, lighter and less wasteful.

"With nanotechnology, you can get those improvements," said Jo Ann Ratto, a polymer research engineer working on the project.

Meals ready to eat, or MREs, come in a packaging system consisting of an outer meal bag, made from a thermoplastic polyolefin, that holds all the food components. A retortable, four-layer pouch--made of aluminum foil, polyethylene, nylon and polyester--holds the entree. Smaller items, such as crackers, are wrapped inside three-layer foil packages.

Aluminum foil has been a favored food packaging material for decades because of its barrier properties. But there are disadvantages, said Jennifer Lucciarini, a materials engineer on the nanomaterials science team at Natick. Foil can be brittle and is susceptible to flex cracks and pin holes when subjected to freezing temperatures. On top of that, foil is non-recyclable, a factor that contributes to the amount of waste produced, she said.

The U.S. military consumes 46.6 million operational rations a year and generates 16,667 tons of ration-related waste in the field, said Ratto.

"There's about seven pounds of waste per soldier per day," she said. MRE packaging waste, including food, is .3 pounds per meal, she added.

"If we get rid of all the foil, we can have [the packaging] be recyclable. That's a big benefit," said Ratto.

The scientists hope these nanocomposite materials will reduce both the MRE weight and packaging waste by 20 percent.

To eliminate the foil, the researchers have produced films and pouches made by blending clay nanoparticles and conventional polymers. These nanocomposites improve the barrier by creating complicated paths for oxygen and water molecules to travel through. In addition, when those nanoclays are well-dispersed within the polymer, the interaction between the clay platelets and polymer chains is maximized, meaning when a force is applied, it has a reinforcement effect and the package won't puncture as easily, said Lucciarini.

MREs must have a three-year shelf life at 80 F, or six months at 100 F, must withstand extreme temperatures and military rough-handling--such as being air-dropped--and must be insect-resistant.

To meet these requirements, the scientists have been testing nanocomposite films and pouches with varying thicknesses.

A 10 mil film costs more, said Ratto, but insects don't go through it.

They are also in the process of scaling up for the non-retortable tri-laminate pouch and have just attained retortable material that they'll look at for the quad-laminate pouch, said Lucciarini.

"We could have an improved meal bag in the system before we actually change anything in the component packaging," said Luc ciarini.