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Development Of Nonwoven Fabrics For Military Applications



nonwoven composite technology lends key performance characteristics to uniforms, equipment



By Stephen Szczesuil, Natick Soldier System



Published May 17, 2006
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The U.S. Marine Corps has taken the initiative to develop state-of-the-art nonwoven composite fabric technology for use as alternate fabric application for Combat Utility Uniforms (CUUs), equipment and shelters. This effort is being conducted via a Small Business Innovative Research (SBIR) contract. Essentially, SBIRs are very competitive and offer the perfect medium in which to conduct what may be termed High-Risk-Technology.

There are generally two phases: Phase I allows a cost of $100,000 for Proof of Concept to be conducted within nine months (six months base + three months option).  If successful, Phase II would allow for a $600,000 + $150,000 (Option Phase II) effort toward bringing the technology to a rapid fruition within two and a half years.

In rare situations, a Phase III effort is allowed toward manufacturing, however, joint partners are necessary to help in receiving matching funding. It must be understood that commercialization of product is critical toward acceptance of each phase.

In the case of the USMC nonwoven SBIR project, Phase I has been successfully completed by an emerging company named Nanosyntex, which is located in Morristown, TN. (For additional SBIR information, go to: www.acq.osd.mil/sadbu/sbir/.)

Nonwovens In Action



This article will discuss the effort toward the development of water or mechanically needled or entangled composite nonwoven fabrics, properties of those developed fabrics as related to current woven military base fabrics, commercial applications, final report briefing, ongoing and planned Phase II tasks and other related aspects including future plans for military application.

These durable nonwoven fabrics can be designed to integrate blends of various fibrous webs that impart water absorbency or repellency, fire and thermal resistance and antimicrobial treatment. These reinforced multi-layer nonwoven composite fabrics have been engineered to be lighter in weight, significantly more breathable and superior in tear and breaking strength as opposed to the conventional woven uniform fabrics. In Phase II, advanced research will be conducted to enhance the durability and wash resistance characteristics for commercial apparel and equipment applications. In addition, the possibility of incorporating fire resistant fibers and additives, barrier materials and nanofiber-based technologies within the nonwoven composite structure will be explored.

The primary goal of SBIR is to develop and incorporate enhanced nonwoven fabrics for military type uniforms, heavy-duty shelter and equipment applications. Nanosyntex stressed the development of a composite uniform nonwoven that possesses high strength, softness, improved abrasion resistance, printability and other related characteristics.   

Nonwovens Outperform Wovens



The objective of SBIR is to utilize the latest nonwoven technology to enhance performance and reduce lifecycle costs for combat-type clothing. The concept includes the development of lightweight composite material that offers high durability, high breaking and tearing strength, breathability and cost reduction to replace current woven uniform material. Included in this plan is the design of a fire retardant (FR) fabric and heavy-duty fabric for tentage and equipment applications.

Typical woven fabrics use old textile technologies that are outdated and generally outsourced to other countries. It uses twisted yarn construction with poor insulation, filtration and barrier properties. Nonwovens, on the other hand, are only a few decades old and offer innovation and technological growth. Nonwovens are fabricated with finer individual fibers that are bonded and/or entangled to supply better insulation, filtration and barrier properties. The strength of nonwoven fabrics is that they can be engineered with specific properties but with a higher production rate, wider widths up to 120 inches and at lower cost with potential for full automation.

Woven fabrics are basically two-dimensional structures with limited flexibility of design and composition and go through at least 14 separate processes, usually conducted in three individual mill operations (i.e. a spinning mill, weaving mill and finishing mill). Nonwovens, on the other hand, contain three-dimensional fabric structures and undergo only five processes or less, potentially done under one roof. Nonwovens are based on web forming processes such as extruded spunbonding process or carding. Nonwoven fabrics for this project then go through either thermal bonding and/or the hydroentangled process.

Phase I Results



The nature of this nonwoven development is such that the external portion of the fabric can be made with totally different properties than the internal portion. Nanosyntex has developed a multilayer nonwoven composite fabric for military garment application that can provide water absorbency on the inside and water repellency on the outside. Just as easily, the outside can be designed to possess flame resistance, chemical protection or other unique properties while the inside, which contacts the skin, remains soft, supple and highly wickable.

Phase I studies indicated that nonwoven composite fabrics can be made 25% lighter and stronger than current woven military uniform fabrics. In addition, they can be made to exhibit more than three times the air permeability or breathability of the current woven military uniform fabrics.

However, the best achievement is that nonwoven fabrics can be both lighter weight and thinner while at the same time  exhibiting higher breaking, tearing and elongation characteristics as well as improved air permeability properties compared to current woven twill uniform fabrics. Other features of the unique nonwoven composites were: a high degree of moisture transport, wrinkle resistance, compatibility with fusible applications, crease-set process or ability to possess permanent creases using silicone RTV beading, a filtering characteristic that would provide optimum sand penetration and the capability to engineer heavy weight nonwovens for tentage or equipment applications.

The Phase I overall proof-of-concept effort was successful to the USMC and therefore Phase II was launched.

Phase II Update



Phase II efforts of this project started in November 2005 with a specific emphasis on optimizing the nonwoven composite fabric construction and processes based on Phase I findings. This would involve improving abrasion, laundered pill resistance and printability along with conducting field tests on nonwoven-based uniforms to gain a better understanding of comfort, physical and mechanical properties. Phase II uniform fabric would offer enhanced abrasion resistance, develop a fire resistant fabric and offer combination water repellent/moisture absorbent composite fabric.  


Pictured above: spunlacing jet manifolds (top); spunlacing production equipment (bottom). These Fleissner units were used by Nanosyntex to develop prototype nonwovens.
Thus far, there are four major Phase II trials involving web development fabricated from 11 carded or drylaid, spunbonded and wetlaid webs. Carded trial for exterior and interior of fabrics included staple polyester with flame retardant, nylon 6, nylon 66, viscose rayon fiber webs ranging in weight from 1.5–3.5 ounces/square yard. All webs were crosslapped to obtain balanced mechanical properties and some were water repellent silicone treated, all at 39-inch widths.

Spunbonded web trials for exterior fabric layers included another 11 developments using polyester and nylon 6 continuous filament fibers ranging from 1.2-3.0 ounces per square yard at 20-inch widths.

The wetlaid nonwoven web trial for interior fabric layer included six variations of polyester and viscose rayon blended staple fibers at two ounces per square yard running at 20-inch widths.

The fourth primary trial was where the webs were hydroentangled using six water jets ranging from 800-3000 PSI. The 28 composite webs were fabricated ranging from 5-8 ounces per square yard. Web widths ranged from 10-27 inches.

At the time this article was written, all composite rolls were in the process of being embossed with both linen and twill patterns. Late in the summer, rolls will be dyed, printed, finished and laboratory tested in preparation for USMC Utility Uniforms to be field-tested.

Future of Nonwovens



Successful commercialization is the future of nonwovens. Getting people to accept nonwovens for clothing and general applications will be the key to success. Thusfar, nonwovens are generally perceived as disposables with a harsh stiff hand and are weak in nature. The goal of this SBIR is to break out of this mode and prove the concept through use of military applications. The military offers the best inroads toward these goals in that nonwovens will be considered for parachutes, tentage and equipment such as duffel bags, backpacks and tarps.

Also, medical applications can be proved out with the use of some nano-particle applications such as silver to make antimicrobial characteristics that may aid in skin infections, carbon tubes to protect against chemical environment, or particles to dispense medicines to wounds.  
               

MAANwear MultiService Nonwoven Cloth



To differentiate current disposable nonwoven applications with durable military goals, we shall refer to the future SBIR development cloth as either MAANWear or MA2Nwear (Marine/Army/AirForce/Navy), not in the sense of gender, but as an acronym for multiservice application and defined as: “Extremely durable, lightweight and fire resistant nonwoven multiservice-based fabric possessing physical properties with a high degree of air permeability, durable press appearance, comfort characteristics, breaking and tearing resistance coupled with the capability to be Silicone Crease-Set, launderable/dry cleanable without the need of undergoing ironing or other after-treatment processes.”

Website Update



Nanosyntex is utilizing its website as a strategy to facilitate commercialization and a means to accelerate the rate of technology transition. This is expected to allow for maximum commercial licensing and strategic alliances in order to bring MA2NWear technology to full fruition.

To keep updated with this SBIR project, USMC wear trial results, other military and commercialization aspects and overall future of nonwovens, visit: www.nanosyntex/maanwear.com.
This article was co-authored by Vasanth Narayanan and Gary Arinder of Nanosyntex, Morristown, TN.