Acetone dissolve the polymer, allowing the gas of foaming agent to escape. The polymer collapses on itself and is more dense because the gas has been removed.

a. It does not have enough strength to withstand.

b. Because lining up the molecule in a way will while being a thin film allow it to be flexible.

No. The structure of cellulose is rigid, the layer can not slide over each other. When a large force is applied, the bond between the layer can be overcome completely, which leads to the total breakage of bonds between the layers.

a. Light weight, stable to be used over a long time, non-toxic, non-soluble in body fluid, cheap

b. Polymethyl methcrylate (PMMA). Soft, transparent, insoluble in body fluid.

c. Hard contact lenses (PMMA), soft contact lenses (Silicone). Soft contact lenses are flexible are allow oxygen to pass through