CM8001

The gas of the foaming agent escapes as acetone dissolves the polymer.
Since the gas has been removed from the polymer, the polymer is now denser.

a. Branched LDPE is too weak and would be too easily cut by surgical tools.

b. Molecules of HDPE need to be aligned in a manner that produces sufficient strength. Linear HDPE allows for sufficient flexibility.

When the piece of plastic is pulled, the molecules become aligned parallel to each other in the direction of the pull.
When the same thing is done to paper, the paper tears as the cellulose molecules in paper are held more rigidly in place and are not free to align parallel to each other. The interactions cannot be formed and broken continuously like in plastic.

a.
1) non-toxic
2) biocompatible
3) durable
4) stable

b. Hard lenses are made of polymethyl methacrylate (PMMA).
Properties: Transparent, some flexibility, low density, hydrophilic.

Soft lenses are made of poly acrylamide
Properties: hydrophilic

c. “Soft” lenses have more water content and higher oxygen permeability, hence they are more comfortable, easier to adjust and stay in place better.