Author Question: Why is the flexural modulus so important for many plastic applications? What will be an ideal ... (Read 89 times)

WWatsford · **on:** Aug 19, 2018

Why is the flexural modulus so important for many plastic applications?

What will be an ideal response?

Question 2

Using a molecular view, explain why compression strength is generally less than tensile strength in polymers.

What will be an ideal response?

nicoleclaire22 · **Reply #1 on:** Aug 19, 2018

Answer to Question 1

Many plastics are used in applications where the plastic is a cover, a seat, or a board-like structure. The most common type of force that these materials would encounter would be flexural. The modulus is often more important than the strength because these materials rarely fail

Answer to Question 2

When a compressive load is applied to a polymer, the molecules are forced closer together. If the polymer is highly crystalline, this force will simply press on the crystals with little damage, much as would happen in a crystalline solid. However, in an amorphous material, such as most plastics, there is considerable space between the polymer chains, which will allow deformation of the polymers at lower stress levels. Furthermore, the spaces allow the polymers to collapse into the holes, thus reducing the ultimate compressive strength. Hence, the compressive forces are lower for polymers than for highly crystalline materials.