Author Question: Explain the relationship between plastic crystallinity and sensitivity to solvent attack. What ... (Read 28 times)

dakota nelson · **on:** Aug 19, 2018

Explain the relationship between plastic crystallinity and sensitivity to solvent attack.

What will be an ideal response?

Question 2

Two samples of the same resin are pulled in tension at two different rates. One is pulled at 1 inch per minute and the other is pulled at 10 inches per minute. Discuss the differences in elongation you would expect, and explain why the differences occur.

What will be an ideal response?

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

Answer to Question 1

Highly crystalline polymers have strong secondary bonds that resist the formation of solvent-polymer bonds or, perhaps, require the formation of more or stronger solvent-polymer bonds to achieve solvent penetration into the polymer network. Hence, crystallinity reduces solvent sensitivity.

Answer to Question 2

You would expect to see a higher elongation in the pieces that were pulled at a slower rate. The slower rate allows the polymer chains time necessary for disentanglement. The forces seen in this case are those of the secondary bonding. At a faster rate, the forces that you see are applied to the backbone of the molecule itself and are generally higher.