Changes

High Density Polyethylene, undergoes the same process as LDPE except lower temperatures are used and a Zeiger Natta catalyst is added (this has a large surface area on which polymerisation occurs, reducing possibility of side branching). The chains of HDPE can be more closely packed together, resulting in higher density and a more rigid structure. HDPE is used extensively in the modern world, including lunch boxes, computer cases etc

High Density Polyethylene, undergoes the same process as LDPE except lower temperatures are used and a Zeiger Natta catalyst is added (this has a large surface area on which polymerisation occurs, reducing possibility of side branching). The chains of HDPE can be more closely packed together, resulting in higher density and a more rigid structure. HDPE is used extensively in the modern world, including lunch boxes, computer cases etc

==Vinyl Chloride==

===Vinyl Chloride===

Polychloroethylene, aka vinyl chloride, contains a chlorine atom which has substituted a hydrogen atom (in a substitution reaction one atom replaces another). This chlorine atom has a higher atomic mass, increasing the density of the polymer and increasing its durability in use. The polymer will decompose under intense heat to form hydrochloric acid (reaction between hydrogen and chlorine atom) which is a fire retardant, causing vinyl chloride to see applications in the building sector.

Polychloroethylene, aka vinyl chloride, contains a chlorine atom which has substituted a hydrogen atom (in a substitution reaction one atom replaces another). This chlorine atom has a higher atomic mass, increasing the density of the polymer and increasing its durability in use. The polymer will decompose under intense heat to form hydrochloric acid (reaction between hydrogen and chlorine atom) which is a fire retardant, causing vinyl chloride to see applications in the building sector.

==Polystyrene==

===Polystyrene===

Polyphenylethylene, also known as polyethylbenzene or polystyrene. In its natural state is very hard and brittle, the phenyl group (C6H5 replacing a hydrogen atom) increases hardness (due to increased [[dispersion forces]]) but decreases density. However, gas can be blown through the liquid polymer during its formation to produce a foam, which is an excellent insulator (the phenyl group does not conduct heat very well) allowing it extensive application in disposable cups.

Polyphenylethylene, also known as polyethylbenzene or polystyrene. In its natural state is very hard and brittle, the phenyl group (C6H5 replacing a hydrogen atom) increases hardness (due to increased [[dispersion forces]]) but decreases density. However, gas can be blown through the liquid polymer during its formation to produce a foam, which is an excellent insulator (the phenyl group does not conduct heat very well) allowing it extensive application in disposable cups.