Question

Polymer-matrix composites (PMCs) which consist of strong fibers embedded in a
resilient plastic that holds them in place are used in the greatest diversity with
applications ranging from commercial aircraft to bath tub. Comment the main drawback
of fiber reinforced PMCs compared with metallic materials.

Answer 1

There are several different types of fiber reinforced PMCs :

1.Glass Fiber–Reinforced Polymer (GFRP) Composites

2. Carbon Fiber–Reinforced Polymer (CFRP) Composites

3. Aramid Fiber–Reinforced Polymer Composites

Lets see the drawbacks of the above PMCs

1.Glass Fiber–Reinforced Polymer (GFRP) Composites :

(a).Eventhough these PMCs have high strength, they lack stiffness. And also they don't have enough rigidity in certain critical applications. (aeroplane and bridge components)

(b). These materials are limited to service temperature of 200 degree celcius. Above this temperature the polymer will disintegrate.

2. Carbon Fiber–Reinforced Polymer (CFRP) Composites

(a). In this PMCs, there is a special requirement that in order to properly adhere the carbon fibers to polymer matrix, special protective epoxy coating is needed.

3. Aramid Fiber–Reinforced Polymer Composites

(a). This PMC is extremely weak in compression.

(b). Working temperature is ? - 200 and 200? degree celcius.

(c). These PMCs degrade in strong bases and acids.

All these drawbacks are with respect to the metallic materails.

An upvote will be highly appreciated.