- Styrofoam packing peanuts are filled with air pockets. When dissolved in acetone, the air trapped in the Styrofoam will be released. Thus, when acetone has evaporated, remaining polystyrene will be much denser.
- a) Branched LDPE is soft and not very strong and hence has a low resistance to being cut. Therefore, branched LDPE cannot be used in this application.
b) In linear HDPE, the weak but extensive dispersion forces allow the molecules to slip pass one another. hence, this enables the plastic to stretch and neck, maintaining a delicate sense of touch for the gloves. - Polymer molecules in plastic have weak dispersion forces that allow the molecules to sip pass one another, allowing the plastic to stretch and neck. When stretched, the molecules become aligned in a way that is parallel to each other, in the direction of the pull. The thickness decrease since the 3D structure is not reversible and will continue decreasing until the plastic breaks/ tears. On the other hand, paper tears rather than stretches as cellulose molecules in the paper are held far more rigidly in place, and the molecules are not free to align.
- a) – Remains stable over the time of use
– Non-toxic
– Non-soluble in body fluids
– Non-reactive in body fluids
b) Contact lenses can be made from different polymers such as polymethyl methacrylate (PMMA), polymacon, hioxifilcon, methanfilcon, and lidofilcon. Properties that are desirable in these materials include being permeable to oxygen, non-toxic, and can easily conform to the shape of the eyes.
c) Hard contact lens are usually made of PMMA, which is a rigid, non-gas permeable plastic. Soft contact lenses are made of silicone, which is very flexible and allows oxygen to reach the eye. Therefore, soft contact lenses are more comfortable to wear.
