THE BIG PICTURE IS SMALL
to a lotus leaf’s hierarchical nonwetting surface, which enables the plant to float and glide on water, or a water strider’s feet, which let the insect walk on water without sinking.
By working on the nano-level, NSRDEC’s scientists and engineers have the oppor- tunity to expand the applications of this technology for the good of the Soldier.
NANO PACKAGED PENNE
Researchers at the Natick Soldier Research, Development and Engineering Center (NSRDEC) are investigating nanocomposite packaging for rations, like the pasta shown here. The packaging may replace foil pouches, enhancing food quality and reducing waste. (Photo by David Kamm, NSRDEC)
THE PERFECT NONFOIL Te Advanced Materials Engineering Team (AMET), part of NSRDEC’s Combat Feeding Directorate (CFD), is investigating high-barrier, polymeric materials for military ration packaging and for food packaging that supports deep space missions for NASA. Nanocompos- ite materials are an ideal packaging choice for shelf-stable processed foods because they can improve the barrier, mechanical and thermal properties of nonfoil food packaging. Polymeric laminates with foil as the barrier are currently being used for ration packaging. Tese structures pro- vide an exceptional barrier to oxygen and moisture, but can also experience stress cracking and pin holing.
NSRDEC is also working on developing and advancing omniphobic and super- omniphobic textiles and other products, which resist dirt, dust and liquids. Omni means “all,” and, in chemistry, phobic doesn’t so much mean fearful as it does a chemical aversion. An omniphobic coating, therefore, is averse to both water (hydro- phobic) and oils (oleophobic). Omniphobic coatings contain micrometer-sized (one 1-millionth of a meter) particles, such as silica, or a combination of micro- and nanometer scale particles. (A nanometer is one 1-billionth of a meter.) When these coatings are applied to textiles or hard sur- faces, such as glass or metal, their surfaces are modified with micro- and nanoscale surface features. Tese features are similar
94 Army AL&T Magazine April–June 2015 “Te incorporation of nanotechnology
into barrier films has proven to be a criti- cal ingredient in our packaging design that will allow us to achieve food protec- tion properties only seen before through the use of foil-based systems,” said Dr. Christopher Tellen, a Ph.D. materials engineer in the CFD. “Te exfoliated dispersion of nanoparticles in polymers forces penetrating oxygen and water vapor molecules
to follow a tortuous
pathway through the packaging material, thereby increasing the time needed to penetrate the packaging and improving barrier properties.”
Nanocomposite packaging can be lighter in weight and less expensive than foil
pouches. Tat reduction in size not only reduces the amount of solid waste and enhances the quality of the rations by pre- serving them better and longer, but it also reduces the warfighter’s logistical burden. NSRDEC is exploring technology that is based on incorporating nanoparticles into thermoplastic resins to create a nanocom- posite material that is 1,000 times smaller than conventional composite material fillers. Nanoparticles have proven to be cost-effective and compatible with many polymers used in packaging.
As a result, the high-barrier, nonfoil poly- meric packaging will comply with the Meal, Ready to Eat requirement of main- taining a three-year shelf life. For space applications, it will maintain up to a five- year shelf life.
NOT YOUR GRANDMA’S CANNING Food sterilization techniques, in com- bination with proper packaging, play an important role in extending shelf life. Retorting, similar to pressure cook- ing, is the food industry’s most common commercial sterilization process for pre- packaged, low-acid foods. Tis process exposes food packages to high moisture and high temperature conditions under pressures of up to 2.5 atmospheres. In some cases, the long retort process leads to a reduction in food quality and limits the types of packaging materials that can be used.
Dr. Jo Ann Ratto, AMET team leader, whose doctorate is in plastics engineering, said that the implementation of a nonfoil structure into food packaging will make it possible to consider novel sterilization methods, such
as microwave-assisted
thermal sterilization (MATS) and pressure-assisted thermal sterilization (PATS). MATS and PATS are desirable alternatives to retort sterilization because
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