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"Kevlar" 49 aramid fiber
was introduced commercially in 1972 and is the Du Pont registered trademark
for its new high strength, high modulus organic fiber. It combines high
tensile strength (43,000 PSI) and high modulus (19 million PSI) with light
weight and toughness superior to other reinforcing fibers for plastics.
It is available in yarns and rovings which meet all FAA requirements for
flammability. It shows no degradation in jet fuel, lubricating oils, water,
salt water or high humidity. At cryogenic temperatures (-320°F.) performance
is excellent with essentially no embrittlement or degradation of fiber
properties. Kevlar 49 can offer both a significant weight saving and improved
stiffness versus glass in addition to superior vibration damping and good
impact resistance. A kayak made with Kevlar 49, for example, weighs about
18 pounds while the weight of a comparable boat made with glass would
be over 30 pounds. The advantages over glass in small aircraft are similar
- weight savings and improved impact resistance. Kevlar 49 is used in
a number of parts on the Lockheed L-1011 because of weight savings of
up to 30% compared to similar parts made of glass. One unusual benefit
of Kevlar is its "quietness". A cowling made of Kevlar will
be quieter and less sensitive to engine vibrations than its glass or graphite
counterpart.
Although all of the processes
used in combining resins with glass fiber are adaptable to Kevlar
49 with little or no modification, it has been found that the
vinyl ester type system is most compatible. The use of polyesters
is not recommended because of poor bonding with Kevlar. The modified
epoxy resin system featured in this catalog is compatible with
Kevlar 49 and has good wetting characteristics.
Kevlar 49 is stocked in
three different fabric styles. Kevlar #120 is a very lightweight
fabric, while #281 and #285 are identical except for the weaving
pattern. Other weights and weaves of Kevlar are available on
a special order basis. Be sure to specify the Kevlar style when
ordering.
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