Question

3. A type of flexible polymer is polymorphic and experiences a change in crystal structure at a pressure of 10 atm. A junior engineer decides that its flexibility would make it very useful as a seal on the robotic arm of a research submarine. Describe (using three to four bullet-points) what might be observed in the first test of the submarine at high pressures and why (consider the worst case scenario).

Answer 1

The overall shape or form of a crystal is known as the morphology. Often, there is more than one crystalline form of the same substance. Each form is known as a polymorph, differing in both the arrangement of constituents as well as unit cell dimensions. Although polymorphs differ in both the shape and size of the unit cell, most compounds may exhibit this behavior under appropriate experimental conditions.

Since the polymer changes its form the structural features of the seal will change.

Its sealing characteristics will be affected as the seal works best when it is flexible as well as in the defined shape.

In the worst case senario if the other polymorphic form is brittle then the seal will completly disintegrate and the robotic arm will collapse as the seal will be holding it together.