Aramid fibers disadvantages

The high moisture absorption of aramid fibers is their biggest disadvantage. It was reported in the literature that moisture absorption by epoxy laminates degrades their mechanical properties. ° ° Hygroscopic fibers provide an easy route for moisture ingress. The addition of aramid fibers to epoxy and phenolic composites slightly improves their flame resistance and decreases smoke formation. ... 

Aramid fibers are widely used as reinforcing fibers in high performance composites. One disadvantage is the poor adhesion to the matrix materials. This arises from the lack of functional groups in the polymer. To overcome the lack of adhesion, the fibers are treated by so-called finish formulations, which is essentially a surface treatment. 

The most common aramid fiber available is the Kevlar 49. These fibers are composed of a highly oriented crystalline polymer and present the highest tensile strength/weight ratio. On the other hand the disadvantages... 

The main disadvantages of the aramid fibers include high moisture absorptivity, low compressive strength, and difficulty in cutting and machining of the resulting composites. 

The standard ASTM D2585 filament wound pressurized bottle test method utilizes a 0.15-m (5.75-in.)intemal diameter filament wound bottle as the test article. This standard test method (with variation in bottle sizes) has been used extensively by the rocket motor industry [47-50] to evaluate glass, aramid, and graphite fiber composite vessel performance. This test method has generally shown good results, but is a relatively expensive test method. Testing of one 0.5-m (20-in.) diameter bottle can cost up to 20K. Other disadvantages are ... 

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