Question

Anisotropy frequently occurs in materials. Suggest how this anisotropy might occur
(hint: consider manufacturing processes) and how a knowledge of the level of anisotropy
might be important when designing components. Use polymer shopping bags as an example. Can anisotropy be “useful”?

Answer 1

ANISOTROPY : It is the property of being dirctionally dependence which implies different axes in different directions .it can be difined as a difference when measured along different axes in a materials physical or mechanical.

ANISOTROPY IN MANUFACTURING PROCESS : 1)Material anisotropy was significant factor in determining the facture path

2) Strength anisotropy can also be seen in vaccum formed polythylene drinking cups.

Example : the cups can be easily torn along the axial direction but they are much more difficult to tear in the circumferential direction.

3)Anisotropy is a material directional dependence of physical property.

4)Anisotropy in polycrystalline materials can also be due to certain texture patterns often produced during manufacturing of materials.

5)Anisotropy in case of rolling ,stringers of texture are produced in the direction of rolling ,which lead to vasty diferent properties in the rolling and in the transverse direction.

6)wood and fiber reinforced composities are very anisotropic,being such stronger along the grain than across it.

ANISOTROPY IN POLYMERS:

Amorophous phase in polymr as well as crystalline phase exhibit significant anisotropy when polymer chains are partially alinged with each other

It is beacuse of the thermal energy transports are more efficiently along the polymer chain.

There are two cases in ehich significant anisotropy is interduced to polymer material:

1)The polymer experiences a mechanical deformation under stretching force.

2)the polymer is deposited onto a substrate by the spin coating and curing process to form a film with a thickness of few micrometres.