Nomex composite

Honeycombs are structures with hexagonal or cylindrical cells made from thin sheets of aluminium, aramid (Nomex), paper or extruded polypropylene. The dimensions of the cells are generally in the range of 5 mm to 10 mm. The two faces are covered with a firmly adherent composite (or sometimes metal) skin. 

Kwolek s task at DuPont was to find a new kind of fiber that was resistant to acids and bases and that would remain stable at high temperatures. In 1964, she discovered such a product, an aromatic polyamide that was five times as strong as steel with half the density of fiberglass. The material was given the name aramid. Aramid was later marketed under the trade names of Kevlar and Nomex . Today, aramid is one of the most widely used substances in polymer matrix composites. 

The aramid fibres (Kevlar and Nomex are the trade names for two of the most common) are especially desirable for their strength-to-weight ratios being superior to metals. They are most often used in composites having polymer matrices (generally epoxies and polyesters). Since the fibres are relatively flexible and somewhat ductile, they may be processed by most common textile operations. 

PinzeUi, R. and Loken, H., Honeycomb cores from NOMEX to KEVLAR aramid papers, JEC Composites, 2004, 8, 133. 

The commonly used synthetic fiber reinforcements are aramid, Nomex , nylon, and Kevlar fibers [19]. The research and development in the fields of synthetic fiber reinforced composites led to the development of aramid fibers. Further research led to the invention of meta and /> r -aramids [20]. Para and meta refer to the positions of the carboxylic and amine groups on the monomer ring. Nomex [21] was produced in the early 1960s and its excellent thermal, chemical, and radiation resistance [22, 23] led to extensive use in defensive clothing, insulation, and as a substitute for asbestos [24]. Additional researches with this /weta-aramid (Nomex) led to the fiber recognized as Kevlar [25]. Kevlar is a / ara-aramid fiber [26]. It was produced and trademarked by DuPont and became commercially accessible in 1973. In the last two decades, the worldwide production and use of aramids has been growing steadily. 

Scaled Composites designed and fabricated the record breaking Voyager aircraft that flew around the world non-stop and non-refueled with a crew of two. To achieve these aims in a time of nine days, the structural weight had to be as low as possible, and the structure as well as the spars, were graphite tape skins on a Nomex honeycomb core. 

Composite-skinned honeycomb panels These may use Nomex nylon paper honeycomb core, aluminium honeycomb or sometimes PVC (polyurethane or acrylic foam core). Dents are not acceptable in composite skins as they indicate fibre damage. Nomex core may split under a dent, so any such damage needs to be cut out and repaired. Nomex honeycomb can absorb considerable amounts of moisture. Wet honeycomb should be thoroughly dried or replaced. Moisture meters are available for use with Fibreglass, Kevlar or Nomex, but these meters will not work with carbon fibre because it is electrically conductive. Instruments that can indicate when carbon-fibre composites are dry enough to repair are few in number and very expensive. 

For the organic and composite materials (filled and unfilled epoxies, NEMA G-10 and FR-5 glass-epoxy composites, Nomex polyamide paper, Kapton polyamide film, and Formvar coating) tested, neither mechanical nor electrical properties are appreciably degraded by a gamma dose of 2 MGy at 5 K. 

Aramid fibers are highly oriented fibers derived from aromatic polyamides, with Kevlar and Nomex as two prominent examples. The woven fabric of aramids combined with phenolic resins produces high-performance composites for ballistic applications, where the projectile energy is mainly absorbed by the fiber with a high strength and modulus (Gardziella et al, 2000). 

Fiber-reinforced composites have high stiffness-to-weight ratios, but this ratio may be increased if, instead of a monolithic structure, two thin composite facesheets of the same weight (for example, plastics reinforced with phenolic glass or carbon fibers), separated by a cellular core, are used. A phenolic resin-impregnated aramid paper honeycomb (Nomex honeycomb) is commonly used in the core structure. These structures are appropriate for applications in which weight reduction and fire safety are critical, such as in ground and air transportation. 

Pinzelh R and Loken H (2004) Honeycomb cores from Nomex to Kevlar aramid papers, JEC Composites 8 133-136. 

Because of their newness, complete panels for A-300 solar cells are not yet available. Moreover, traditional panel construction with its steel backing is not viable for the robot. Thus, we will construct the solar panels in house, using quarter-inch honeycomb sandwich panels (Nomex core with fiberglass facing). The cell will be encapsulated in silicone. Similar honeycomb composite will be used to make the chassis box (Figure 8). The constraction and joinery of honeycomb panels are mature technologies in the aerospace field, and these materials supply area densities of 1.4 kg/m for solar panels and 2.5 kg/m for chassis walls. 

Crystalline aromatic polyamides are also used in fiber applications. An example of this type of material is Kevlar , a high-strength fiber used in bulletproof vests and in composite structures. A similar material, which can be processed more easily, is Nomex . It can be used to give flame retardance to cloth when used as a coating. ... 

Figure 18.2 Manual transfer of MTV composition crumb in a vacuum oven at Space Ordnance Systems, Canyon, CA, USA in 1980s. Safety note standard protective clothing has changed since. Operations require grounding of the operator and Nomex-type overall with balaclava and additional faceshield.

Nylons prepared from aromatic diamines and aromatic dicarboxylic acids can lead to very high-heat aromatic nylons (aramids). Poly (m-phenyleneisoph-thalamide), MPIA, is made from the condensation polymerization of m-phenylenediamine and isoph-thaloyl chloride and has a Tg of 280°C. Its structure is shown in Fig. 1.3. W. Sweeny, a scientist at DuPont was responsible for discoveries leading to the commercialization of MPIA and is available under the Nomex trade name. MPIA is used in fibers to make heat-resistant and flame-retardant apparel, electrical insulation, and composites. 

Typical Use Metals and honeycombs (BR227 primer recommended). Typical Use Aerospace metals composites (inc. wet Nomex cores). ... 

Applications have been reported for the use of nitrile rubber/phenolic adhesives in the bonding of wood and polyurethane foam to various substrates. Mitsubishi Electric Corp. patented a two-part adhesive composition for Nomex paper (Table 25). 

NITRILE RUBBER ADHESIVES 221 Table 25. Adhesive Composition for Nomex Paper. 

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