CM8001

There is a lot of air in styrofoam and they get removed when immersed in acetone, leaving the denser styrofoam without air. Polymer change into a more compact structure and is thus less dense.

A. LDPE is not strong enough as compared to HDPE
B. HDPE molecules can line up to produce strength and by using a thin HDPE, it will give a strong yet flexible material.

Stretching plastic bag causes molecules to be aligned parallel to each other in direction of pull. However, paper is made of cellulose molecules that are held more rigidly in place and are not able to align. So they just break.

A. Biodegradable, stable, non-toxic, long half-life. Mechanical properties depend on its uses.
B. (PMMA) It is strong and able to retain shape.
C. Hard contact lenses contain polymethyl methacrylate with some silicon to make it flexible. They retain shape better than soft contact lens.