CM8001

When the polystyrene comes into contact with acetone, it acts as a molecular lubricant allowing the polymer chains to slide around each other hence, the styrofoam becomes soft and releases the air bubbles, consequently resulting in a denser polystyrene solid.

a. It does not have the required strength to resist a cut
b. The HDPE molecules must line up in a way that they provide the correct amount of strength/resilience, using a thin liner of HDPE allows sufficient flexibility while still being strong.

No, paper does not stretch.
For the plastic bag, there are the weak but extensive dispersion forces also allow the molecules to slip pass one another allowing the plastic to stretch and “neck”. When force is applied to a piece of paper, it results in a tear instead of stretching. This is because the cellulose molecules of the paper are held far more rigidly in place and are not free to become aligned.

a. resistant to corrosion, durable, non-toxic, inert, semi-permeable (allowing essential materials to diffuse allowing for material transport).
b. semi-rigid gas permeable polymers (e.g. polymathy methacrylate). Transparent, low density, inert, easy to hold, hydrophilic, allows oxygen to pass through.
c. Hard contact lenses are not oxygen permeable, while soft contact lenses are. The use and formulation will be different. Structure, branching and linearity affect the ease of wearing contact lenses