CM8001

Since styrofoam is made of foaming agent, when acetone is added to it, the air in the foam will be released resulting in the styrofoam to harden and is now more dense.

a) Branched LDPE is not very strong.

b) Although dispersion forces are weak, they are extensive in terms of surface area. Linear HDPE is more flexible and this allows molecules to slip past one another and HDPE is able to stretch.

Molecular structure of paper is comparable to that of cellulose. The weak intermolecular forces and intramolecular hydrogen bonds will allow the molecules to slide pass one another in plastics. Whereas, dispersion forces present in paper does not allow the paper to stretch. Instead, they tear when pulled apart.

a) The four general properties of polymers are non-toxic, lack of reactivity with body fluid, durability, non-degradable.

b) Poly(methyl methacrylate) in short, PMMA. Desirable properties include transparency, does not break easily, light weight and comfortable to wear.

c) PMMA or silicon-based polymers was used for older versions of hard contact lens, and the key characteristic is that it is not gas permeable which means that there must be ways to ensure the eyes still received a constant supply of oxygen. The way is to induce natural tears and this is done by making the lenses smaller, not as fitting, in order to introduce oxygen and tears to wash, hence increasing discomfort too.