Acetone dissolves the polymer, allowing the gas of the foaming agent to escape. Therefore, the polymer will collapse as a result of the gas escaping, which will then cause solid Styrofoam to be more dense.

a) LDPE cannot be used in this application as it does not have the required resistance to breakage.

B) The molecules of HDPE must line up in a way that produces the required resistance to breakage. This can be achieve by using a thin layer of HDPE which will then allow it to achieve sufficient flexibility.

When the piece of plastic is stretched, the strip narrows and “necks down”, the molecules will then become aligned parallel to one another, in the direction that it is being pulled. However, this is an irreversible action as the three-dimensional structure is being altered. In addition, if the plastic is continued being pulled, it’ll eventually break.

On the other hand, if the same pulling force is applied to a piece of paper, the paper will break instead of being stretch as the cellulose molecule present in the paper are held more rigidly in place and thus not free to be aligned.

a) The benefits desired are polymers should be stable over time of intended usage, it must be non toxic to the body, it also should have a low-cost factor and lastly, it must be of low solubility and reactivity in the human body.

b) Hard contact lenses are made from Polymethyl methacrylate (PMMA), which are used for rigid gas permeable lenses, and soft contact lenses are made of hydrogel and silicone hydrogen which are water absorbing polymers. In soft lenses, properties such as comfortable usage, flexible and definitely needs to allow oxygen to reach the eye. On the other hand, hard lenses definitely have to be non toxic to the eye and it also must have to allow high level of oxygen of breathability.

c) The difference between hard and soft lensesto is due to the material used, an example hard lenses material would be Polymethyl methacrylate (PMMA) and soft lenses would be silicon hydrogel (water absorbing polymer). Soft contact lenses tends to be more flexible and it also allows sufficient oxygen to reach the eye, which indirectly allows wearing of soft contact lenses to be more comfortable.