Materials - Modulus of polymer and metal

[yy205001]

Homework Statement

Why is there such a large difference between the elastic moduli of metals and polymers?

Homework Equations

The Attempt at a Solution

I am thinking because of the different bonding between metals and polymers. Since metals have metallic bonding and polymers have different bonding (Covalent or Hydrogen bond? I am so sure about this) which is much weaker than metallic bonding, so it is much easier to stretch polymers.

Is this correct?

Thank you!

 

[Mat-E Engineer]

Good afternoon,

The biggest differences between the two is their atom structure and bond type. Metals are arranged in a crystal lattice, where some polymers are arranged in chains (Think a mess of spaghetti). Using this understanding, can you explain each step of deformation for a plastic and metal?

Why does the metal have a larger elastic deformation portion while the polymer has a longer plastic (irreversible) deformation portion?

Why does the end of the polymer's curve go up when the metal's goes down? (You already hinted to this in your work.)

When you answer his question and research some more sources like your textbook and the one posted below, you should be able to answer this question easily.

Polymer Source: http://www.virginia.edu/bohr/mse209/chapter16.htm