Question 3
Papers will not be able to produce the same stretch as plastics. Plastics are made up of High Density Polyethylene (HDPE) that consists of long chains of (CH2)n molecules. Between these molecular chains are weak but extensive dispersion forces that hold the chains in place. These dispersion forces are responsible for enabling the molecules to slip pass one another, causing the plastic to stretch. However, papers are primarily made up of cellulose (C6H10O5)n containing intra and intermolecular hydrogen bonds, which do not allow the molecules to slip pass each other. When the paper is being pulled, these hydrogen bonds break and as a result, the paper tears.
Question 4
a) 1)Non-Toxic 2)Stable 3)Low reactivity with body fluids 4)Low solubility with body fluids
b)There are different types of contact lenses available in the market.Hard contact lenses are made of PMMA (poly methacrylate).Soft contact lenses on the other hand are made of Polymacon which is a polymer of 2-hydroxyethyl methacrylate (HEMA). The properties that are desirable in these materials are it being non-toxic and permeable to oxygen. c)Hard contact lenses are rigid and non-gas permeable, this may be uncomfortable for the user.Soft contact lenses are made of silicone, which is flexible and allows oxygen to reach the eyes.This is why soft contact lenses are more comfortable.
