TEXTILES.ORG
Composites have mind-bending properties and endless applications.
By Katherine Carlson
It sounds like science fiction: portable airport hangars supported by columns of air, paper that conducts electricity and synthetic mother-of-pearl that can be bent without breaking.
We have now entered The Matrix, but don’t expect to see Keanu Reeves in a black coat defying gravity and leading a cyberpunk revolution. The revolutionaries developing composite materials with remarkable practical applications are more likely to wear lab coats and have their feet firmly planted in reality.
“Composites are a huge growth industry right now,” says Phillip Gill, president of Royal Plastic Manufacturing, Minden, Neb., which makes both rigid and flexible ducting for aerospace applications. “Demand is expected to triple in the next few years. The outlook is very optimistic.”
Greater than the sum of its parts
Composites consist of at least two materials which, when combined, have properties distinct from either. “In practice, most composites consist of a bulk material (the ‘matrix’) and a reinforcement of some kind,” writes David Cripps of Gurit Inc., an advanced composite material company based in Wattwil, Switzerland. “The reinforcement is usually in fiber form.” In a guide to composites on the netcomposites Web site (www.netcomposites.com), Cripps describes three main types: polymer matrix composites (also called fiber reinforced polymers), metal matrix composites and ceramic matrix composites.
Flexible composites, generally polymer matrix types, can be straightforward combinations of commonly-used materials. Seaman Corp., Wooster, Ohio, manufactures performance fabrics, including Shelter-Lite™ tarp. The nylon fabric coated with polyvinyl chloride (PVC) is 28% lighter, more flexible in the cold and requires fewer repairs. In this case, PVC (which would not hold up as well to rugged wear and weather on its own) is the matrix, nylon fabric the reinforcement. The result is stronger than either component by itself—not breaking news.
The news is that more matrix and reinforcement combinations are available than ever before, allowing manufacturers to create custom materials for unusual applications. Royal’s flexible ducting is suited to systems subject to continuous movement or vibration, severe misalignment with control equipment, corrosive environments and extreme weather—a natural for aerospace applications.
The matrices Royal uses include standard rubber, neoprene, and nitrile, fluorinated and butyl elastomers. The reinforcements include fiberglass (high strength, low cost), nylon (flexibility), Nomex® (flame-resistant) and cotton (low cost). The challenge is to find the right composite, the right price and the right partners to bring new applications to market.
Partnership is the pivotal part of the equation. Developing new matrix types and new fabrics, fibers or additives is cutting-edge science, and many of the methods used to create composites are expensive and proprietary in nature. Aeronautic, automotive and military product manufacturers can invest in scientific development with the expectation of big rewards. Less weight and fewer breakdowns can help a helicopter manufacturer, for example, save fuel, cut maintenance costs and reduce down time. Businesses without big research and development budgets can find a toehold in the world of composites by pairing up with academic institutions or other manufacturers with the expertise, matrix or fabric they lack.
Going back to school
In southwest Missouri, an incubator for new composites emerged from a partnership between the Center for Applied Science and Engineering (CASE) at Missouri State University and the Springfield Area Chamber of Commerce. To foster use of advanced materials by Springfield businesses, CASE “will conduct industry-oriented ‘high-risk’ research and technology development to help reduce the industry-assumed risk in taking a concept to product,” according to the CASE Web site (http://jvic.missouristate.edu/case).
Crosslink, St. Louis, Mo., a leader in development and manufacture of conductive electroluminescent polymers, operates a facility at Missouri State in Springfield and is reaping the benefits of collaboration. The company is positioned to become a $1.5 billion industry in 2008, with products such as SuperFlex™ leading the way.
SuperFlex is a crushable, durable, lightweight technology based on a conductive polymer that emits light in the near infrared spectrums. It can be integrated with textiles, composites, plastics and metals, bringing light to military tents, troop carriers, ships and submarines—all places where light that is lightweight, flexible and flat makes a huge difference. Flexible lighting can be deployed rapidly, minimize space needs and reduce shipping costs.
“SuperFlex is created by a layering process,” says Steve Welker, general manager of commercial development for Crosslink. “It consists of a flexible substrate with a transparent electronic polymer or other coatings screen-printed on it.” The polymer, polyethylene dioxy-thiophene (PEDOT), conducts electricity from a standard AC power source. The white light from SuperFlex is diffuse, cool to the touch and can be fabricated in large sizes, making it appropriate for a range of applications.
In this case, the matrix isn’t strengthened or hardened, but changes function while retaining flexibility. Heat is an essential ingredient to the manufacture of many composite materials, and autoclaves or other curing processes create or cement unique properties. “Pressure and heat break some chemical bonds and fix others,” says Welker, creating the crosslinks for which the company was named.
Crosslink recently launched a new venture with Missouri State, the commercial development of a polymer with a surface that reacts to— and detoxifies—biological agents. Tents with this smart coating provide collective protection to troops exposed to chemical or biological agents and are being deployed now in Iraq.
“There are lots of opportunities out there,” says Welker, but he doesn’t see SuperFlex installed in event tents, awnings or canopies just yet. The flat, flexible composite technology is expensive, compared to conventional lighting solutions that work well with those products. The key to using flexible composite solutions successfully in new products is “to find your niche,” says Welker.
A meeting of minds and materials
Bally Ribbon Mills, Bally, Pa., is one of the largest suppliers of narrow industrial fabric in the world and now weaves high-strength foundations for flexible composite products made by its strategic partner, V System Composites (VSC), Anaheim, Calif.
Bally developed a multi-dimensional, 3D continuous weaving method to fabricate engineered yarns containing nylon, Kevlar, carbon or even quartz into net-shaped structures. These strong, woven structural pre-forms serve as foundations for aerospace and military parts formed by VSC’s patented vacuum-assisted resin transfer moulding (VARTM) process. “This is a win-win alliance for both of our companies because it strengthens the portfolio of VSC by providing a needed capability for engineered pre-forms, and allows BRM to offer fabrication of finished, structural products to its customers,” says Mike Louderback, president of VSC.
The U.S. Army Research, Development and Engineering Command contracted with VSC to develop composite structural components for helicopter platforms. The $20 million, five-year contract focuses on replacing heavy metal components with lightweight composites to achieve 40% weight reduction, 30% cost reduction, and 30% less maintenance on materials that resist corrosion, damage and fatigue better than metal.
The academic link has been important to VSC as well. The University of Delaware Center for Composite Materials (UD-CCM), Newark, Del., hosts a consortium of 60 member businesses (of which VSC is one) with access to laboratory facilities and expertise and the opportunity to partner with UD-CCM in proposals for research funding in areas of common interest.
Best partner, biggest customer
It isn’t surprising that the military partners with industry, sponsors research and purchases composite technology. The Center of Excellence for Inflatable Composite Structures, located at the U.S. Army Soldier Systems Center, Natick, Mass., works with Vertigo Inc., Lake Elsinore, Calif., on AirBeam™ shelters. The Army awarded Vertigo a five-year contract to manufacture an Air-Supported TEMPER tent, a 58m2 shelter that can be deployed by two soldiers in less than 10 minutes.
AirBeams consist of continuously braided or woven 3-D fabric sleeves over air retention bladders. These seamless tubes from two to 102cm in diameter can support huge weights when inflated with compressed air, but in tent technology weigh one-third as much as aluminum and take up less than one-fourth the volume.
AirBeam technology raises flexible composites to new heights—literally. Inflatable space structures, unfolding aircraft wings, and parachutes able to float heavy materials to earth are among the applications. With new matrix polymers and a range of additives that strengthen or add function, the potential seems limitless. “We can think of a lot of applications at Natick, but others think of areas we never expected,” says Amy Soo Leighton, a chemical engineer.
Defy gravity without leaving home
The “gee whiz” composites grab the headlines, but flexibility plus strength equals success in many applications. Consider fiber-resin column wraps that repair bridges and buildings (Xxsys Technologies Inc., San Diego, Calif.); flat, flexible lightbulbs that can be tailored to complex shapes and sizes (CeeLite, Blue Bell, Penn.); or a bullet-proof plastic topper for troop carriers (Amtech Corporation Inc., Wapato, Wash.).
Check for special institutes or centers for composite material science at major colleges and universities. You may be able to enter the matrix without traveling far from home.