CM8001

The acetone results in the dissolution of the polymer, allowing the gas of the foaming agent to escape. This results in the polymer collapsing on itself and becoming more dense as a result of the escaped gas.

a. LDPE cannot be used because it is not strong enough
b. The molecules of HDPE must line up in a way that produces the required strength. Using a thin liner of HDPE allows sufficient flexibility

When plastic is stretched, it results in the the polymers becoming aligned to each other in the direction of the pull. This change in structure is irreversible and will remain. However, when paper is pulled apart, it will tear because the polymers that paper is made of is not as flexible.

a. Insoluble in body fluids, unreactive with body fluids, stable (non-biodegradable) , non-toxic

b, Hard lenses are made of polymethyl methacrylate. Softer contact lenses are made of silicone and more recently, newer rigid gas permeable (RGP) polymers contain fluorine: fluoro-silicone-acrylate polymers and fluoro-silicones.

c.The differences between the materials are their flexibility and oxygen permeability, hence the soft lenses are more comfortable.